1 .\" Copyright (c) 1994, 2019, Oracle and/or its affiliates. All rights reserved. 2 .\" DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 3 .\" 4 .\" This code is free software; you can redistribute it and/or modify it 5 .\" under the terms of the GNU General Public License version 2 only, as 6 .\" published by the Free Software Foundation. 7 .\" 8 .\" This code is distributed in the hope that it will be useful, but WITHOUT 9 .\" ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 10 .\" FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 11 .\" version 2 for more details (a copy is included in the LICENSE file that 12 .\" accompanied this code). 13 .\" 14 .\" You should have received a copy of the GNU General Public License version 15 .\" 2 along with this work; if not, write to the Free Software Foundation, 16 .\" Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 17 .\" 18 .\" Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 19 .\" or visit www.oracle.com if you need additional information or have any 20 .\" questions. 21 .\" 22 .\" Automatically generated by Pandoc 2.3.1 23 .\" 24 .TH "JAVAC" "1" "2018" "JDK 13" "JDK Commands" 25 .hy 26 .SH NAME 27 .PP 28 javac \- read Java class and interface definitions and compile them into 29 bytecode and class files 30 .SH SYNOPSIS 31 .PP 32 \f[CB]javac\f[R] [\f[I]options\f[R]] [\f[I]sourcefiles\f[R]] 33 .TP 34 .B \f[I]options\f[R] 35 Command\-line options. 36 See \f[B]Overview of javac Options\f[R]. 37 .RS 38 .RE 39 .TP 40 .B \f[I]sourcefiles\f[R] 41 One or more source files to be compiled (such as \f[CB]MyClass.java\f[R]) 42 or processed for annotations (such as \f[CB]MyPackage.MyClass\f[R]). 43 .RS 44 .RE 45 .SH DESCRIPTION 46 .PP 47 The \f[CB]javac\f[R] command reads class and interface definitions, 48 written in the Java programming language, and compiles them into 49 bytecode class files. 50 The \f[CB]javac\f[R] command can also process annotations in Java source 51 files and classes. 52 .PP 53 A new launcher environment variable, \f[CB]JDK_JAVAC_OPTIONS\f[R], was 54 introduced in JDK 9 that prepended its content to the command line to 55 \f[CB]javac\f[R] . 56 See \f[B]Using JDK_JAVAC_OPTIONS Environment Variable\f[R]. 57 .PP 58 There are two ways to pass source code file names to \f[CB]javac\f[R]. 59 .IP \[bu] 2 60 For a small number of source files, you can list the file names on the 61 command line. 62 .IP \[bu] 2 63 For a large number of source files, you can use the 64 \f[CB]\@\f[R]\f[I]filename\f[R] option on the \f[CB]javac\f[R] command line 65 to include a file that lists the source file names. 66 See \f[B]Standard Options\f[R] for a description of the option and 67 \f[B]javac Command\-Line Argument Files\f[R] for a description of 68 \f[CB]javac\f[R] argument files. 69 .PP 70 Source code file names must have \f[CB]\&.java\f[R] suffixes, class file 71 names must have \f[CB]\&.class\f[R] suffixes, and both source and class 72 files must have root names that identify the class. 73 For example, a class called \f[CB]MyClass\f[R] would be written in a 74 source file called \f[CB]MyClass.java\f[R] and compiled into a bytecode 75 class file called \f[CB]MyClass.class\f[R]. 76 .PP 77 Inner class definitions produce additional class files. 78 These class files have names that combine the inner and outer class 79 names, such as \f[CB]MyClass$MyInnerClass.class\f[R]. 80 .PP 81 You should arrange the source files in a directory tree that reflects 82 their package tree. 83 For example: 84 .IP \[bu] 2 85 \f[B]Oracle Solaris, Linux, and OS X:\f[R] If all of your source files 86 are in \f[CB]/workspace\f[R], then put the source code for 87 \f[CB]com.mysoft.mypack.MyClass\f[R] in 88 \f[CB]/workspace/com/mysoft/mypack/MyClass.java\f[R]. 89 .IP \[bu] 2 90 \f[B]Windows:\f[R] If all of your source files are in 91 \f[CB]\\workspace\f[R], then put the source code for 92 \f[CB]com.mysoft.mypack.MyClass\f[R] in 93 \f[CB]\\workspace\\com\\mysoft\\mypack\\MyClass.java\f[R]. 94 .PP 95 By default, the compiler puts each class file in the same directory as 96 its source file. 97 You can specify a separate destination directory with the \f[CB]\-d\f[R] 98 option described in \f[B]Standard Options\f[R]. 99 .SH PROGRAMMATIC INTERFACE 100 .PP 101 The \f[CB]javac\f[R] command supports the new Java Compiler API defined by 102 the classes and interfaces in the \f[CB]javax.tools\f[R] package. 103 .SH IMPLICITLY LOADED SOURCE FILES 104 .PP 105 To compile a set of source files, the compiler might need to implicitly 106 load additional source files. 107 See \f[B]Searching for Types\f[R]. 108 Such files are currently not subject to annotation processing. 109 By default, the compiler gives a warning when annotation processing 110 occurs and any implicitly loaded source files are compiled. 111 The \f[CB]\-implicit\f[R] option provides a way to suppress the warning. 112 .SH USING JDK_JAVAC_OPTIONS ENVIRONMENT VARIABLE 113 .PP 114 The content of the \f[CB]JDK_JAVAC_OPTIONS\f[R] environment variable, 115 separated by white\-spaces ( ) or white\-space characters (\f[CB]\\n\f[R], 116 \f[CB]\\t\f[R], \f[CB]\\r\f[R], or \f[CB]\\f\f[R]) is prepended to the command 117 line arguments passed to \f[CB]javac\f[R] as a list of arguments. 118 .PP 119 The encoding requirement for the environment variable is the same as the 120 \f[CB]javac\f[R] command line on the system. 121 \f[CB]JDK_JAVAC_OPTIONS\f[R] environment variable content is treated in 122 the same manner as that specified in the command line. 123 .PP 124 Single quotes (\f[CB]\[aq]\f[R]) or double quotes (\f[CB]"\f[R]) can be used 125 to enclose arguments that\ contain whitespace characters. 126 All content between the open quote and the first matching close quote 127 are preserved by simply removing the pair of quotes. 128 In case a matching quote is not found, the launcher will abort with an 129 error message. 130 \f[CB]\@\f[R]\f[I]files\f[R] are supported as they are specified in the 131 command line. 132 However, as in \f[CB]\@\f[R]\f[I]files\f[R], use of a wildcard is not 133 supported. 134 .PP 135 \f[B]Examples of quoting arguments containing white spaces:\f[R] 136 .RS 137 .PP 138 \f[CB]export\ JDK_JAVAC_OPTIONS=\[aq]\@"C:\\white\ spaces\\argfile"\[aq]\f[R] 139 .RE 140 .RS 141 .PP 142 \f[CB]export\ JDK_JAVAC_OPTIONS=\[aq]"\@C:\\white\ spaces\\argfile"\[aq]\f[R] 143 .RE 144 .RS 145 .PP 146 \f[CB]export\ JDK_JAVAC_OPTIONS=\[aq]\@C:\\"white\ spaces"\\argfile\[aq]\f[R] 147 .RE 148 .SH OVERVIEW OF JAVAC OPTIONS 149 .PP 150 The compiler has sets of standard options, and cross\-compilation 151 options that are supported on the current development environment. 152 The compiler also has a set of nonstandard options that are specific to 153 the current virtual machine and compiler implementations but are subject 154 to change in the future. 155 The nonstandard options begin with \f[CB]\-X\f[R] . 156 The different sets of \f[CB]javac\f[R] options are described in the 157 following sections: 158 .IP \[bu] 2 159 \f[B]Standard Options\f[R] 160 .IP \[bu] 2 161 \f[B]Cross\-Compilation Options for javac\f[R] 162 .IP \[bu] 2 163 \f[B]Extra Options\f[R] 164 .SH STANDARD OPTIONS 165 .TP 166 .B \f[CB]\@\f[R]\f[I]filename\f[R] 167 Reads options and file names from a file. 168 To shorten or simplify the \f[CB]javac\f[R] command, you can specify one 169 or more files that contain arguments to the \f[CB]javac\f[R] command 170 (except \f[CB]\-J\f[R] options). 171 This lets you to create \f[CB]javac\f[R] commands of any length on any 172 operating system. 173 See \f[B]javac Command\-Line Argument Files\f[R]. 174 .RS 175 .RE 176 .TP 177 .B \f[CB]\-A\f[R]\f[I]key\f[R][\f[CB]=\f[R]\f[I]value\f[R]] 178 Specifies options to pass to annotation processors. 179 These options aren\[aq]t interpreted by \f[CB]javac\f[R] directly, but are 180 made available for use by individual processors. 181 The \f[I]key\f[R] value should be one or more identifiers separated by a 182 dot (\f[CB]\&.\f[R]). 183 .RS 184 .RE 185 .TP 186 .B \f[CB]\-\-add\-modules\f[R] \f[I]module\f[R]\f[CB],\f[R]\f[I]module\f[R] 187 Specifies root modules to resolve in addition to the initial modules, or 188 all modules on the module path if \f[I]module\f[R] is 189 \f[CB]ALL\-MODULE\-PATH.\f[R] 190 .RS 191 .RE 192 .TP 193 .B \f[CB]\-\-boot\-class\-path\f[R] \f[I]path\f[R] or \f[CB]\-bootclasspath\f[R] \f[I]path\f[R] 194 Overrides the location of the bootstrap class files. 195 .RS 196 .PP 197 \f[B]Note:\f[R] 198 .PP 199 This can only be used when compiling for versions prior to JDK 9. 200 As applicable, see the descriptions in\ \f[CB]\-\-release\f[R], 201 \f[CB]\-source\f[R], or \f[CB]\-target\f[R]\ for details. 202 .RE 203 .TP 204 .B \f[CB]\-\-class\-path\f[R] \f[I]path\f[R], \f[CB]\-classpath\f[R] \f[I]path\f[R], or \f[CB]\-cp\f[R] \f[I]path\f[R] 205 Specifies where to find user class files and annotation processors. 206 This class path overrides the user class path in the \f[CB]CLASSPATH\f[R] 207 environment variable. 208 .RS 209 .IP \[bu] 2 210 If \f[CB]\-\-class\-path\f[R], \f[CB]\-classpath\f[R], or \f[CB]\-cp\f[R] 211 aren\[aq]t specified, then the user class path is the current directory. 212 .IP \[bu] 2 213 If the \f[CB]\-sourcepath\f[R] option isn\[aq]t specified, then the user 214 class path is also searched for source files. 215 .IP \[bu] 2 216 If the \f[CB]\-processorpath\f[R] option isn\[aq]t specified, then the 217 class path is also searched for annotation processors. 218 .RE 219 .TP 220 .B \f[CB]\-d\f[R] \f[I]directory\f[R] 221 Sets the destination directory for class files. 222 If a class is part of a package, then \f[CB]javac\f[R] puts the class file 223 in a subdirectory that reflects the package name and creates directories 224 as needed. 225 For example: 226 .RS 227 .IP \[bu] 2 228 \f[B]Oracle Solaris, Linux, and OS X:\f[R] If you specify 229 \f[CB]\-d\ /home/myclasses\f[R] and the class is called 230 \f[CB]com.mypackage.MyClass\f[R], then the class file is 231 \f[CB]/home/myclasses/com/mypackage/MyClass.class\f[R]. 232 .IP \[bu] 2 233 \f[B]Windows:\f[R] If you specify \f[CB]\-d\ C:\\myclasses\f[R] and the 234 class is called \f[CB]com.mypackage.MyClass\f[R], then the class file is 235 \f[CB]C:\\myclasses\\com\\mypackage\\MyClass.class\f[R]. 236 .PP 237 If the \f[CB]\-d\f[R] option isn\[aq]t specified, then \f[CB]javac\f[R] puts 238 each class file in the same directory as the source file from which it 239 was generated. 240 .PP 241 \f[B]Note:\f[R] 242 .PP 243 The directory specified by the \f[CB]\-d\f[R] option isn\[aq]t 244 automatically added to your user class path. 245 .RE 246 .TP 247 .B \f[CB]\-deprecation\f[R] 248 Shows a description of each use or override of a deprecated member or 249 class. 250 Without the \f[CB]\-deprecation\f[R] option, \f[CB]javac\f[R] shows a 251 summary of the source files that use or override deprecated members or 252 classes. 253 The \f[CB]\-deprecation\f[R] option is shorthand for 254 \f[CB]\-Xlint:deprecation\f[R]. 255 .RS 256 .RE 257 .TP 258 .B \f[CB]\-\-enable\-preview\f[R] 259 Enables preview language features. 260 Used in conjunction with either \f[CB]\-source\f[R] or 261 \f[CB]\-\-release\f[R]. 262 .RS 263 .RE 264 .TP 265 .B \f[CB]\-encoding\f[R] \f[I]encoding\f[R] 266 Specifies character encoding used by source files, such as EUC\-JP and 267 UTF\-8. 268 If the \f[CB]\-encoding\f[R] option isn\[aq]t specified, then the platform 269 default converter is used. 270 .RS 271 .RE 272 .TP 273 .B \f[CB]\-endorseddirs\f[R] \f[I]directories\f[R] 274 Overrides the location of the endorsed standards path. 275 .RS 276 .PP 277 \f[B]Note:\f[R] 278 .PP 279 This can only be used when compiling for versions prior to JDK 9. 280 As applicable, see the descriptions in\ \f[CB]\-\-release\f[R], 281 \f[CB]\-source\f[R], or \f[CB]\-target\f[R]\ for details. 282 .RE 283 .TP 284 .B \f[CB]\-extdirs\f[R] \f[I]directories\f[R] 285 Overrides the location of the installed extensions. 286 The \f[CB]directories\f[R] variable is a colon\-separated list of 287 directories. 288 Each JAR file in the specified directories is searched for class files. 289 All JAR files found become part of the class path. 290 .RS 291 .PP 292 If you are cross\-compiling, then this option specifies the directories 293 that contain the extension classes. 294 See \f[B]Cross\-Compilation Options for javac\f[R]. 295 .PP 296 \f[B]Note:\f[R] 297 .PP 298 This can only be used when compiling for versions prior to JDK 9. 299 As applicable, see the descriptions in\ \f[CB]\-\-release\f[R], 300 \f[CB]\-source\f[R], or \f[CB]\-target\f[R]\ for details. 301 .RE 302 .TP 303 .B \f[CB]\-g\f[R] 304 Generates all debugging information, including local variables. 305 By default, only line number and source file information is generated. 306 .RS 307 .RE 308 .TP 309 .B \f[CB]\-g:\f[R][\f[CB]lines\f[R], \f[CB]vars\f[R], \f[CB]source\f[R]] 310 Generates only the kinds of debugging information specified by the 311 comma\-separated list of keywords. 312 Valid keywords are: 313 .RS 314 .TP 315 .B \f[CB]lines\f[R] 316 Line number debugging information. 317 .RS 318 .RE 319 .TP 320 .B \f[CB]vars\f[R] 321 Local variable debugging information. 322 .RS 323 .RE 324 .TP 325 .B \f[CB]source\f[R] 326 Source file debugging information. 327 .RS 328 .RE 329 .RE 330 .TP 331 .B \f[CB]\-g:none\f[R] 332 Doesn\[aq]t generate debugging information. 333 .RS 334 .RE 335 .TP 336 .B \f[CB]\-h\f[R] \f[I]directory\f[R] 337 Specfies where to place generated native header files. 338 .RS 339 .PP 340 When you specify this option, a native header file is generated for each 341 class that contains native methods or that has one or more constants 342 annotated with the \f[B]\f[BC]java.lang.annotation.Native\f[B]\f[R] 343 [https://docs.oracle.com/javase/10/docs/api/java/lang/annotation/Native.html] 344 annotation. 345 If the class is part of a package, then the compiler puts the native 346 header file in a subdirectory that reflects the package name and creates 347 directories as needed. 348 .RE 349 .TP 350 .B \f[CB]\-\-help\f[R], \f[CB]\-help\f[R] or \f[CB]\-?\f[R] 351 Prints a synopsis of the standard options. 352 .RS 353 .RE 354 .TP 355 .B \f[CB]\-\-help\-extra\f[R] or \f[CB]\-X\f[R] 356 Prints the help for extra options. 357 .RS 358 .RE 359 .TP 360 .B \f[CB]\-implicit:\f[R][\f[CB]none\f[R], \f[CB]class\f[R]] 361 Specifies whether or not to generate class files for implicitly 362 referenced files: 363 .RS 364 .IP \[bu] 2 365 \f[CB]\-implicit:class\f[R] \-\-\- Automatically generates class files. 366 .IP \[bu] 2 367 \f[CB]\-implicit:none\f[R] \-\-\- Suppresses class file generation. 368 .PP 369 If this option isn\[aq]t specified, then the default automatically 370 generates class files. 371 In this case, the compiler issues a warning if any class files are 372 generated when also doing annotation processing. 373 The warning isn\[aq]t issued when the \f[CB]\-implicit\f[R] option is 374 explicitly set. 375 See \f[B]Searching for Types\f[R]. 376 .RE 377 .TP 378 .B \f[CB]\-J\f[R]\f[I]option\f[R] 379 Passes \f[I]option\f[R] to the runtime system, where \f[I]option\f[R] is 380 one of the Java options described on \f[B]java\f[R] command. 381 For example, \f[CB]\-J\-Xms48m\f[R] sets the startup memory to 48 MB. 382 .RS 383 .PP 384 \f[B]Note:\f[R] 385 .PP 386 The \f[CB]CLASSPATH\f[R] environment variable, \f[CB]\-classpath\f[R] 387 option, \f[CB]\-bootclasspath\f[R] option, and \f[CB]\-extdirs\f[R] option 388 don\[aq]t specify the classes used to run \f[CB]javac\f[R]. 389 Trying to customize the compiler implementation with these options and 390 variables is risky and often doesn\[aq]t accomplish what you want. 391 If you must customize the complier implementation, then use the 392 \f[CB]\-J\f[R] option to pass options through to the underlying Java 393 launcher. 394 .RE 395 .TP 396 .B \f[CB]\-\-limit\-modules\f[R] \f[I]module\f[R]\f[CB],\f[R]\f[I]module\f[R]* 397 Limits the universe of observable modules. 398 .RS 399 .RE 400 .TP 401 .B \f[CB]\-\-module\f[R] \f[I]module\-name\f[R] or \f[CB]\-m\f[R] \f[I]module\-name\f[R] 402 Compiles only the specified module and checks time stamps. 403 .RS 404 .RE 405 .TP 406 .B \f[CB]\-\-module\-path\f[R] \f[I]path\f[R] or \f[CB]\-p\f[R] \f[I]path\f[R] 407 Specifies where to find application modules. 408 .RS 409 .RE 410 .TP 411 .B \f[CB]\-\-module\-source\-path\f[R] \f[I]module\-source\-path\f[R] 412 Specifies where to find input source files for multiple modules. 413 .RS 414 .RE 415 .TP 416 .B \f[CB]\-\-module\-version\f[R] \f[I]version\f[R] 417 Specifies the version of modules that are being compiled. 418 .RS 419 .RE 420 .TP 421 .B \f[CB]\-nowarn\f[R] 422 Disables warning messages. 423 This option operates the same as the \f[CB]\-Xlint:none\f[R] option. 424 .RS 425 .RE 426 .TP 427 .B \f[CB]\-parameters\f[R] 428 Generates metadata for reflection on method parameters. 429 Stores formal parameter names of constructors and methods in the 430 generated class file so that the method 431 \f[CB]java.lang.reflect.Executable.getParameters\f[R] from the Reflection 432 API can retrieve them. 433 .RS 434 .RE 435 .TP 436 .B \f[CB]\-proc:\f[R][\f[CB]none\f[R], \f[CB]only\f[R]] 437 Controls whether annotation processing and compilation are done. 438 \f[CB]\-proc:none\f[R] means that compilation takes place without 439 annotation processing. 440 \f[CB]\-proc:only\f[R] means that only annotation processing is done, 441 without any subsequent compilation. 442 .RS 443 .RE 444 .TP 445 .B \f[CB]\-processor\f[R] \f[I]class1\f[R][\f[CB],\f[R]\f[I]class2\f[R]\f[CB],\f[R]\f[I]class3\f[R]...] 446 Names of the annotation processors to run. 447 This bypasses the default discovery process. 448 .RS 449 .RE 450 .TP 451 .B \f[CB]\-\-processor\-module\-path\f[R] \f[I]path\f[R] 452 Specifies the module path used for finding annotation processors. 453 .RS 454 .RE 455 .TP 456 .B \f[CB]\-\-processor\-path\f[R] \f[I]path\f[R] or \f[CB]\-processorpath\f[R] \f[I]path\f[R] 457 Specifies where to find annotation processors. 458 If this option isn\[aq]t used, then the class path is searched for 459 processors. 460 .RS 461 .RE 462 .TP 463 .B \f[CB]\-profile\f[R] \f[I]profile\f[R] 464 Checks that the API used is available in the specified profile. 465 .RS 466 .PP 467 \f[B]Note:\f[R] 468 .PP 469 This can only be used when compiling for versions prior to JDK 9. 470 As applicable, see the descriptions in\ \f[CB]\-\-release\f[R], 471 \f[CB]\-source\f[R], or \f[CB]\-target\f[R]\ for details. 472 .RE 473 .TP 474 .B \f[CB]\-\-release\f[R] \f[I]release\f[R] 475 Compiles source code according to the rules of the Java programming 476 language for the specified Java SE release, generating class files 477 suitable for that release. 478 Additionally, compiles source code against the API of the specified Java 479 SE release and the API supported by the corresponding JDK release. 480 The supported values of \f[I]release\f[R] are the current Java SE release 481 and a limited number of previous releases. 482 The exact set of supported values is given in the command\-line help. 483 .RS 484 .PP 485 The API of a Java SE release consists of the \f[CB]java.*\f[R], 486 \f[CB]javax.*\f[R], and \f[CB]org.*\f[R] packages that are exported by Java 487 SE modules in the release. 488 .PP 489 The API supported by a JDK release consists of the \f[CB]com.*\f[R] and 490 \f[CB]jdk.*\f[R] packages that are exported by JDK modules in the release, 491 plus the \f[CB]javax.*\f[R] packages that are exported by standard, but 492 non\-Java SE, modules in the release. 493 .PP 494 \f[B]Note:\f[R] 495 .PP 496 The \f[CB]\-\-add\-exports\f[R] option cannot be used to enlarge the set 497 of packages exported by the Java SE and JDK API. 498 .RE 499 .TP 500 .B \f[CB]\-s\f[R] \f[I]directory\f[R] 501 Specifies the directory used to place the generated source files. 502 If a class is part of a package, then the compiler puts the source file 503 in a subdirectory that reflects the package name and creates directories 504 as needed. 505 For example: 506 .RS 507 .IP \[bu] 2 508 \f[B]Oracle Solaris, Linux, and OS X:\f[R] If you specify 509 \f[CB]\-s\ /home/mysrc\f[R] and the class is called 510 \f[CB]com.mypackage.MyClass\f[R], then the source file is put in 511 \f[CB]/home/mysrc/com/mypackage/MyClass.java\f[R]. 512 .IP \[bu] 2 513 \f[B]Windows:\f[R] If you specify \f[CB]\-s\ C:\\mysrc\f[R] and the class 514 is called \f[CB]com.mypackage.MyClass\f[R], then the source file is put in 515 \f[CB]C:\\mysrc\\com\\mypackage\\MyClass.java\f[R]. 516 .RE 517 .TP 518 .B \f[CB]\-\-source\f[R] \f[I]release\f[R] or \f[CB]\-source\f[R] \f[I]release\f[R] 519 Compiles source code according to the rules of the Java programming 520 language for the specified Java SE release. 521 The supported values of \f[I]release\f[R] are the current Java SE release 522 and a limited number of previous releases. 523 The exact set of supported values is given in the command\-line help. 524 .RS 525 .PP 526 If the option is not specified, the default is to compile source code 527 according to the rules of the Java programming language for the current 528 Java SE release. 529 .RE 530 .TP 531 .B \f[CB]\-\-source\-path\f[R] \f[I]path\f[R] or \f[CB]\-sourcepath\f[R] \f[I]path\f[R] 532 Specifies where to find input source files. 533 This is the source code path used to search for class or interface 534 definitions. 535 As with the user class path, source path entries are separated by colons 536 (\f[CB]:\f[R]) on Oracle Solaris and semicolons (\f[CB];\f[R]) on Windows. 537 They can be directories, JAR archives, or ZIP archives. 538 If packages are used, then the local path name within the directory or 539 archive must reflect the package name. 540 .RS 541 .PP 542 \f[B]Note:\f[R] 543 .PP 544 Classes found through the class path might be recompiled when their 545 source files are also found. 546 See \f[B]Searching for Types\f[R]. 547 .RE 548 .TP 549 .B \f[CB]\-\-system\f[R] \f[I]jdk\f[R] | \f[CB]none\f[R] 550 Overrides the location of system modules. 551 .RS 552 .RE 553 .TP 554 .B \f[CB]\-\-target\f[R] \f[I]release\f[R] or \f[CB]\-target\f[R] \f[I]release\f[R] 555 Generates \f[CB]class\f[R] files suitable for the specified Java SE 556 release. 557 The supported values of \f[I]release\f[R] are the current Java SE release 558 and a limited number of previous releases. 559 The exact set of supported values is given in the command\-line help. 560 .RS 561 .PP 562 \f[B]Note:\f[R] 563 .PP 564 It is an error to specify a value for \f[I]release\f[R] that is lower 565 than the the release for which the source code is being compiled. 566 (See \f[CB]\-\-source\f[R]). 567 .RE 568 .TP 569 .B \f[CB]\-\-upgrade\-module\-path\f[R] \f[I]path\f[R] 570 Overrides the location of upgradeable modules. 571 .RS 572 .RE 573 .TP 574 .B \f[CB]\-verbose\f[R] 575 Outputs messages about what the compiler is doing. 576 Messages include information about each class loaded and each source 577 file compiled. 578 .RS 579 .RE 580 .TP 581 .B \f[CB]\-\-version\f[R] or \f[CB]\-version\f[R] 582 Prints version information. 583 .RS 584 .RE 585 .TP 586 .B \f[CB]\-Werror\f[R] 587 Terminates compilation when warnings occur. 588 .RS 589 .RE 590 .SH CROSS\-COMPILATION OPTIONS FOR JAVAC 591 .PP 592 By default, for releases prior to JDK 9, classes were compiled against 593 the bootstrap classes of the platform that shipped with 594 the\f[CB]javac\f[R] command. 595 But \f[CB]javac\f[R] also supports cross\-compiling, in which classes are 596 compiled against bootstrap classes of a different Java platform 597 implementation. 598 It\[aq]s important to use the \f[CB]\-bootclasspath\f[R] and 599 \f[CB]\-extdirs\f[R] options when cross\-compiling. 600 .PP 601 \f[B]Note:\f[R] 602 .PP 603 This can only be used when compiling for versions prior to JDK 9. 604 As applicable, see the descriptions in\ \f[CB]\-\-release\f[R], 605 \f[CB]\-source\f[R], or \f[CB]\-target\f[R]\ for details. 606 .SH EXTRA OPTIONS 607 .TP 608 .B \f[CB]\-\-add\-exports\f[R] \f[I]module\f[R]\f[CB]/\f[R]\f[I]package\f[R]\f[CB]=\f[R]\f[I]other\-module\f[R](\f[CB],\f[R]\f[I]other\-module\f[R])* 609 Specifies a package to be considered as exported from its defining 610 module to additional modules or to all unnamed modules when the value of 611 \f[I]other\-module\f[R] is \f[CB]ALL\-UNNAMED\f[R]. 612 .RS 613 .RE 614 .TP 615 .B \f[CB]\-\-add\-reads\f[R] \f[I]module\f[R]\f[CB]=\f[R]\f[I]other\-module\f[R](\f[CB],\f[R]\f[I]other\-module\f[R])* 616 Specifies additional modules to be considered as required by a given 617 module. 618 .RS 619 .RE 620 .TP 621 .B \f[CB]\-\-default\-module\-for\-created\-files\f[R] \f[I]module\-name\f[R] 622 Specifies the fallback target module for files created by annotation 623 processors, if none is specified or inferred. 624 .RS 625 .RE 626 .TP 627 .B \f[CB]\-Djava.endorsed.dirs=\f[R]\f[I]dirs\f[R] 628 Overrides the location of the endorsed standards path. 629 .RS 630 .PP 631 \f[B]Note:\f[R] 632 .PP 633 This can only be used when compiling for versions prior to JDK 9. 634 As applicable, see the descriptions in\ \f[CB]\-\-release\f[R], 635 \f[CB]\-source\f[R], or \f[CB]\-target\f[R]\ for details. 636 .RE 637 .TP 638 .B \f[CB]\-Djava.ext.dirs=\f[R]\f[I]dirs\f[R] 639 Overrides the location of installed extensions. 640 .RS 641 .PP 642 \f[B]Note:\f[R] 643 .PP 644 This can only be used when compiling for versions prior to JDK 9. 645 As applicable, see the descriptions in\ \f[CB]\-\-release\f[R], 646 \f[CB]\-source\f[R], or \f[CB]\-target\f[R]\ for details. 647 .RE 648 .TP 649 .B \f[CB]\-\-doclint\-format\f[R] [\f[CB]html4\f[R]|\f[CB]html5\f[R]] 650 Specifies the format for documentation comments. 651 .RS 652 .RE 653 .TP 654 .B \f[CB]\-\-patch\-module\f[R] \f[I]module\f[R]\f[CB]=\f[R]\f[I]file\f[R](\f[CB]:\f[R]\f[I]file\f[R])* 655 Overrides or augments a module with classes and resources in JAR files 656 or directories. 657 .RS 658 .RE 659 .TP 660 .B \f[CB]\-Xbootclasspath:\f[R]\f[I]path\f[R] 661 Overrides the location of the bootstrap class files. 662 .RS 663 .PP 664 \f[B]Note:\f[R] 665 .PP 666 This can only be used when compiling for versions prior to JDK 9. 667 As applicable, see the descriptions in\ \f[CB]\-\-release\f[R], 668 \f[CB]\-source\f[R], or \f[CB]\-target\f[R]\ for details. 669 .RE 670 .TP 671 .B \f[CB]\-Xbootclasspath/a:\f[R]\f[I]path\f[R] 672 Adds a suffix to the bootstrap class path. 673 .RS 674 .PP 675 \f[B]Note:\f[R] 676 .PP 677 This can only be used when compiling for versions prior to JDK 9. 678 As applicable, see the descriptions in\ \f[CB]\-\-release\f[R], 679 \f[CB]\-source\f[R], or \f[CB]\-target\f[R]\ for details. 680 .RE 681 .TP 682 .B \f[CB]\-Xbootclasspath/p:\f[R]\f[I]path\f[R] 683 Adds a prefix to the bootstrap class path. 684 .RS 685 .PP 686 \f[B]Note:\f[R] 687 .PP 688 This can only be used when compiling for versions prior to JDK 9. 689 As applicable, see the descriptions in\ \f[CB]\-\-release\f[R], 690 \f[CB]\-source\f[R], or \f[CB]\-target\f[R]\ for details. 691 .RE 692 .TP 693 .B \f[CB]\-Xdiags:\f[R][\f[CB]compact\f[R], \f[CB]verbose\f[R]] 694 Selects a diagnostic mode. 695 .RS 696 .RE 697 .TP 698 .B \f[CB]\-Xdoclint\f[R] 699 Enables recommended checks for problems in \f[CB]javadoc\f[R] comments 700 .RS 701 .RE 702 .TP 703 .B \f[CB]\-Xdoclint:\f[R](\f[CB]all\f[R]|\f[CB]none\f[R]|[\f[CB]\-\f[R]]\f[I]group\f[R])[\f[CB]/\f[R]\f[I]access\f[R]] 704 Enables or disables specific groups of checks, 705 .RS 706 .PP 707 \f[I]group\f[R] can have one of the following values: 708 .IP \[bu] 2 709 \f[CB]accessibility\f[R] 710 .IP \[bu] 2 711 \f[CB]html\f[R] 712 .IP \[bu] 2 713 \f[CB]missing\f[R] 714 .IP \[bu] 2 715 \f[CB]reference\f[R] 716 .IP \[bu] 2 717 \f[CB]syntax\f[R] 718 .PP 719 The variable \f[I]access\f[R] specifies the minimum visibility level of 720 classes and members that the \f[CB]\-Xdoclint\f[R] option checks. 721 It can have one of the following values (in order of most to least 722 visible): 723 .IP \[bu] 2 724 \f[CB]public\f[R] 725 .IP \[bu] 2 726 \f[CB]protected\f[R] 727 .IP \[bu] 2 728 \f[CB]package\f[R] 729 .IP \[bu] 2 730 \f[CB]private\f[R] 731 .PP 732 The default \f[I]access\f[R] level is \f[CB]private\f[R]. 733 .PP 734 For more information about these groups of checks, see the 735 \f[CB]\-Xdoclint\f[R] option of the \f[CB]javadoc\f[R] command. 736 The \f[CB]\-Xdoclint\f[R] option is disabled by default in the 737 \f[CB]javac\f[R] command. 738 .PP 739 For example, the following option checks classes and members (with all 740 groups of checks) that have the access level of protected and higher 741 (which includes protected and public): 742 .RS 743 .PP 744 \f[CB]\-Xdoclint:all/protected\f[R] 745 .RE 746 .PP 747 The following option enables all groups of checks for all access levels, 748 except it won\[aq]t check for HTML errors for classes and members that 749 have the access level of package and higher (which includes package, 750 protected and public): 751 .RS 752 .PP 753 \f[CB]\-Xdoclint:all,\-html/package\f[R] 754 .RE 755 .RE 756 .TP 757 .B \f[CB]\-Xdoclint/package:\f[R][\f[CB]\-\f[R]]\f[I]packages\f[R](\f[CB],\f[R][\f[CB]\-\f[R]]\f[I]package\f[R])* 758 Enables or disables checks in specific packages. 759 Each \f[I]package\f[R] is either the qualified name of a package or a 760 package name prefix followed by \f[CB]\&.*\f[R], which expands to all 761 sub\-packages of the given package. 762 Each \f[I]package\f[R] can be prefixed with a hyphen (\f[CB]\-\f[R]) to 763 disable checks for a specified package or packages. 764 .RS 765 .RE 766 .TP 767 .B \f[CB]\-Xlint\f[R] 768 Enables all recommended warnings. 769 In this release, enabling all available warnings is recommended. 770 .RS 771 .RE 772 .TP 773 .B \f[CB]\-Xlint:\f[R][\f[CB]\-\f[R]]\f[I]key\f[R](\f[CB],\f[R][\f[CB]\-\f[R]]\f[I]key\f[R])* 774 Supplies warnings to enable or disable, separated by comma. 775 Precede a key by a hyphen (\f[CB]\-\f[R]) to disable the specified 776 warning. 777 .RS 778 .PP 779 Supported values for \f[I]key\f[R] are: 780 .IP \[bu] 2 781 \f[CB]all\f[R]: Enables all warnings. 782 .IP \[bu] 2 783 \f[CB]auxiliaryclass\f[R]: Warns about an auxiliary class that\[aq]s 784 hidden in a source file, and is used from other files. 785 .IP \[bu] 2 786 \f[CB]cast\f[R]: Warns about the use of unnecessary casts. 787 .IP \[bu] 2 788 \f[CB]classfile\f[R]: Warns about the issues related to classfile 789 contents. 790 .IP \[bu] 2 791 \f[CB]deprecation\f[R]: Warns about the use of deprecated items. 792 .IP \[bu] 2 793 \f[CB]dep\-ann\f[R]: Warns about the items marked as deprecated in 794 \f[CB]javadoc\f[R] but without the \f[CB]\@Deprecated\f[R] annotation. 795 .IP \[bu] 2 796 \f[CB]divzero\f[R]: Warns about the division by the constant integer 0. 797 .IP \[bu] 2 798 \f[CB]empty\f[R]: Warns about an empty statement after \f[CB]if\f[R]. 799 .IP \[bu] 2 800 \f[CB]exports\f[R]: Warns about the issues regarding module exports. 801 .IP \[bu] 2 802 \f[CB]fallthrough\f[R]: Warns about the falling through from one case of a 803 switch statement to the next. 804 .IP \[bu] 2 805 \f[CB]finally\f[R]: Warns about \f[CB]finally\f[R] clauses that don\[aq]t 806 terminate normally. 807 .IP \[bu] 2 808 \f[CB]module\f[R]: Warns about the module system\-related issues. 809 .IP \[bu] 2 810 \f[CB]opens\f[R]: Warns about the issues related to module opens. 811 .IP \[bu] 2 812 \f[CB]options\f[R]: Warns about the issues relating to use of command line 813 options. 814 .IP \[bu] 2 815 \f[CB]overloads\f[R]: Warns about the issues related to method overloads. 816 .IP \[bu] 2 817 \f[CB]overrides\f[R]: Warns about the issues related to method overrides. 818 .IP \[bu] 2 819 \f[CB]path\f[R]: Warns about the invalid path elements on the command l 820 ine. 821 .IP \[bu] 2 822 \f[CB]processing\f[R]: Warns about the issues related to annotation 823 processing. 824 .IP \[bu] 2 825 \f[CB]rawtypes\f[R]: Warns about the use of raw types. 826 .IP \[bu] 2 827 \f[CB]removal\f[R]: Warns about the use of an API that has been marked for 828 removal. 829 .IP \[bu] 2 830 \f[CB]requires\-automatic\f[R]: Warns developers about the use of 831 automatic modules in requires clauses. 832 .IP \[bu] 2 833 \f[CB]requires\-transitive\-automatic\f[R]: Warns about automatic modules 834 in requires transitive. 835 .IP \[bu] 2 836 \f[CB]serial\f[R]: Warns about the serializable classes that don\[aq]t 837 provide a serial version ID. 838 Also warns about access to non\-public members from a serializable 839 element. 840 .IP \[bu] 2 841 \f[CB]static\f[R]: Warns about the accessing a static member using an 842 instance. 843 .IP \[bu] 2 844 \f[CB]try\f[R]: Warns about the issues relating to the use of try blocks ( 845 that is, try\-with\-resources). 846 .IP \[bu] 2 847 \f[CB]unchecked\f[R]: Warns about the unchecked operations. 848 .IP \[bu] 2 849 \f[CB]varargs\f[R]: Warns about the potentially unsafe \f[CB]vararg\f[R] 850 methods. 851 .IP \[bu] 2 852 \f[CB]none\f[R]: Disables all warnings. 853 .PP 854 See \f[B]Examples of Using \-Xlint keys\f[R]. 855 .RE 856 .TP 857 .B \f[CB]\-Xmaxerrs\f[R] \f[I]number\f[R] 858 Sets the maximum number of errors to print. 859 .RS 860 .RE 861 .TP 862 .B \f[CB]\-Xmaxwarns\f[R] \f[I]number\f[R] 863 Sets the maximum number of warnings to print. 864 .RS 865 .RE 866 .TP 867 .B \f[CB]\-Xpkginfo:\f[R][\f[CB]always\f[R], \f[CB]legacy\f[R], \f[CB]nonempty\f[R]] 868 Specifies when and how the \f[CB]javac\f[R] command generates 869 \f[CB]package\-info.class\f[R] files from \f[CB]package\-info.java\f[R] 870 files using one of the following options: 871 .RS 872 .TP 873 .B \f[CB]always\f[R] 874 Generates a \f[CB]package\-info.class\f[R] file for every 875 \f[CB]package\-info.java\f[R] file. 876 This option may be useful if you use a build system such as Ant, which 877 checks that each \f[CB]\&.java\f[R] file has a corresponding 878 \f[CB]\&.class\f[R] file. 879 .RS 880 .RE 881 .TP 882 .B \f[CB]legacy\f[R] 883 Generates a \f[CB]package\-info.class\f[R] file only if 884 \f[CB]package\-info.java\f[R] contains annotations. 885 This option doesn\[aq]t generate a \f[CB]package\-info.class\f[R] file if 886 \f[CB]package\-info.java\f[R] contains only comments. 887 .RS 888 .PP 889 \f[B]Note:\f[R] 890 .PP 891 A \f[CB]package\-info.class\f[R] file might be generated but be empty if 892 all the annotations in the \f[CB]package\-info.java\f[R] file have 893 \f[CB]RetentionPolicy.SOURCE\f[R]. 894 .RE 895 .TP 896 .B \f[CB]nonempty\f[R] 897 Generates a \f[CB]package\-info.class\f[R] file only if 898 \f[CB]package\-info.java\f[R] contains annotations with 899 \f[CB]RetentionPolicy.CLASS\f[R] or \f[CB]RetentionPolicy.RUNTIME\f[R]. 900 .RS 901 .RE 902 .RE 903 .TP 904 .B \f[CB]\-Xplugin:\f[R]\f[I]name\f[R] \f[I]args\f[R] 905 Specifies the name and optional arguments for a plug\-in to be run. 906 .RS 907 .RE 908 .TP 909 .B \f[CB]\-Xprefer:\f[R][\f[CB]source\f[R], \f[CB]newer\f[R]] 910 Specifies which file to read when both a source file and class file are 911 found for an implicitly compiled class using one of the following 912 options. 913 See \f[B]Searching for Types\f[R]. 914 .RS 915 .IP \[bu] 2 916 \f[CB]\-Xprefer:newer\f[R]: Reads the newer of the source or class files 917 for a type (default). 918 .IP \[bu] 2 919 \f[CB]\-Xprefer:source\f[R] : Reads the source file. 920 Use \f[CB]\-Xprefer:source\f[R] when you want to be sure that any 921 annotation processors can access annotations declared with a retention 922 policy of \f[CB]SOURCE\f[R]. 923 .RE 924 .TP 925 .B \f[CB]\-Xprint\f[R] 926 Prints a textual representation of specified types for debugging 927 purposes. 928 This doesn\[aq]t perform annotation processing or compilation. 929 The format of the output could change. 930 .RS 931 .RE 932 .TP 933 .B \f[CB]\-XprintProcessorInfo\f[R] 934 Prints information about which annotations a processor is asked to 935 process. 936 .RS 937 .RE 938 .TP 939 .B \f[CB]\-XprintRounds\f[R] 940 Prints information about initial and subsequent annotation processing 941 rounds. 942 .RS 943 .RE 944 .TP 945 .B \f[CB]\-Xstdout\f[R] \f[I]filename\f[R] 946 Sends compiler messages to the named file. 947 By default, compiler messages go to \f[CB]System.err\f[R]. 948 .RS 949 .RE 950 .SH JAVAC COMMAND\-LINE ARGUMENT FILES 951 .PP 952 An argument file can include \f[CB]javac\f[R] options and source file 953 names in any combination. 954 The arguments within a file can be separated by spaces or new line 955 characters. 956 If a file name contains embedded spaces, then put the whole file name in 957 double quotation marks. 958 .PP 959 File names within an argument file are relative to the current 960 directory, not to the location of the argument file. 961 Wildcards (*) aren\[aq]t allowed in these lists (such as for specifying 962 \f[CB]*.java\f[R]). 963 Use of the at sign (\f[CB]\@\f[R]) to recursively interpret files 964 isn\[aq]t supported. 965 The \f[CB]\-J\f[R] options aren\[aq]t supported because they\[aq]re passed 966 to the launcher, which doesn\[aq]t support argument files. 967 .PP 968 When executing the \f[CB]javac\f[R] command, pass in the path and name of 969 each argument file with the at sign (\f[CB]\@\f[R]) leading character. 970 When the \f[CB]javac\f[R] command encounters an argument beginning with 971 the at sign (\f[CB]\@\f[R]), it expands the contents of that file into the 972 argument list. 973 .SH EXAMPLES OF USING JAVAC \@FILENAME 974 .TP 975 .B Single Argument File 976 You could use a single argument file named \f[CB]argfile\f[R] to hold all 977 \f[CB]javac\f[R] arguments: 978 .RS 979 .RS 980 .PP 981 \f[CB]javac\ \@argfile\f[R] 982 .RE 983 .PP 984 This argument file could contain the contents of both files shown in the 985 following \f[B]Two Argument Files\f[R] example. 986 .RE 987 .TP 988 .B Two Argument Files 989 You can create two argument files: one for the \f[CB]javac\f[R] options 990 and the other for the source file names. 991 Note that the following lists have no line\-continuation characters. 992 .RS 993 .PP 994 Create a file named \f[CB]options\f[R] that contains the following: 995 .PP 996 \f[B]Oracle Solaris, Linux, and OS X:\f[R] 997 .IP 998 .nf 999 \f[CB] 1000 \-d\ classes 1001 \-g 1002 \-sourcepath\ /java/pubs/ws/1.3/src/share/classes 1003 \f[R] 1004 .fi 1005 .PP 1006 \f[B]Windows:\f[R] 1007 .IP 1008 .nf 1009 \f[CB] 1010 \-d\ classes 1011 \-g 1012 \-sourcepath\ C:\\java\\pubs\\ws\\1.3\\src\\share\\classes 1013 \f[R] 1014 .fi 1015 .PP 1016 Create a file named \f[CB]classes\f[R] that contains the following: 1017 .IP 1018 .nf 1019 \f[CB] 1020 MyClass1.java 1021 MyClass2.java 1022 MyClass3.java 1023 \f[R] 1024 .fi 1025 .PP 1026 Then, run the \f[CB]javac\f[R] command as follows: 1027 .RS 1028 .PP 1029 \f[CB]javac\ \@options\ \@classes\f[R] 1030 .RE 1031 .RE 1032 .TP 1033 .B Argument Files with Paths 1034 The argument files can have paths, but any file names inside the files 1035 are relative to the current working directory (not \f[CB]path1\f[R] or 1036 \f[CB]path2\f[R]): 1037 .RS 1038 .RS 1039 .PP 1040 \f[CB]javac\ \@path1/options\ \@path2/classes\f[R] 1041 .RE 1042 .RE 1043 .SH EXAMPLES OF USING \-XLINT KEYS 1044 .TP 1045 .B \f[CB]cast\f[R] 1046 Warns about unnecessary and redundant casts, for example: 1047 .RS 1048 .RS 1049 .PP 1050 \f[CB]String\ s\ =\ (String)\ "Hello!"\f[R] 1051 .RE 1052 .RE 1053 .TP 1054 .B \f[CB]classfile\f[R] 1055 Warns about issues related to class file contents. 1056 .RS 1057 .RE 1058 .TP 1059 .B \f[CB]deprecation\f[R] 1060 Warns about the use of deprecated items. 1061 For example: 1062 .RS 1063 .IP 1064 .nf 1065 \f[CB] 1066 java.util.Date\ myDate\ =\ new\ java.util.Date(); 1067 int\ currentDay\ =\ myDate.getDay(); 1068 \f[R] 1069 .fi 1070 .PP 1071 The method \f[CB]java.util.Date.getDay\f[R] has been deprecated since JDK 1072 1.1. 1073 .RE 1074 .TP 1075 .B \f[CB]dep\-ann\f[R] 1076 Warns about items that are documented with the \f[CB]\@deprecated\f[R] 1077 Javadoc comment, but don\[aq]t have the \f[CB]\@Deprecated\f[R] 1078 annotation, for example: 1079 .RS 1080 .IP 1081 .nf 1082 \f[CB] 1083 /** 1084 \ \ *\ \@deprecated\ As\ of\ Java\ SE\ 7,\ replaced\ by\ {\@link\ #newMethod()} 1085 \ \ */ 1086 public\ static\ void\ deprecatedMethod()\ {\ } 1087 public\ static\ void\ newMethod()\ {\ } 1088 \f[R] 1089 .fi 1090 .RE 1091 .TP 1092 .B \f[CB]divzero\f[R] 1093 Warns about division by the constant integer 0, for example: 1094 .RS 1095 .RS 1096 .PP 1097 \f[CB]int\ divideByZero\ =\ 42\ /\ 0;\f[R] 1098 .RE 1099 .RE 1100 .TP 1101 .B \f[CB]empty\f[R] 1102 Warns about empty statements after \f[CB]if\f[R]statements, for example: 1103 .RS 1104 .IP 1105 .nf 1106 \f[CB] 1107 class\ E\ { 1108 \ \ \ \ void\ m()\ { 1109 \ \ \ \ \ \ \ \ \ if\ (true)\ ; 1110 \ \ \ \ } 1111 } 1112 \f[R] 1113 .fi 1114 .RE 1115 .TP 1116 .B \f[CB]fallthrough\f[R] 1117 Checks the switch blocks for fall\-through cases and provides a warning 1118 message for any that are found. 1119 Fall\-through cases are cases in a switch block, other than the last 1120 case in the block, whose code doesn\[aq]t include a break statement, 1121 allowing code execution to fall through from that case to the next case. 1122 For example, the code following the case 1 label in this switch block 1123 doesn\[aq]t end with a break statement: 1124 .RS 1125 .IP 1126 .nf 1127 \f[CB] 1128 switch\ (x)\ { 1129 case\ 1: 1130 \ \ System.out.println("1"); 1131 \ \ //\ No\ break\ statement\ here. 1132 case\ 2: 1133 \ \ System.out.println("2"); 1134 } 1135 \f[R] 1136 .fi 1137 .PP 1138 If the \f[CB]\-Xlint:fallthrough\f[R] option was used when compiling this 1139 code, then the compiler emits a warning about possible fall\-through 1140 into case, with the line number of the case in question. 1141 .RE 1142 .TP 1143 .B \f[CB]finally\f[R] 1144 Warns about \f[CB]finally\f[R] clauses that can\[aq]t be completed 1145 normally, for example: 1146 .RS 1147 .IP 1148 .nf 1149 \f[CB] 1150 public\ static\ int\ m()\ { 1151 \ \ try\ { 1152 \ \ \ \ \ throw\ new\ NullPointerException(); 1153 \ \ }\ \ catch\ (NullPointerException();\ { 1154 \ \ \ \ \ System.err.println("Caught\ NullPointerException."); 1155 \ \ \ \ \ return\ 1; 1156 \ \ \ }\ finally\ { 1157 \ \ \ \ \ return\ 0; 1158 \ \ \ } 1159 \ \ } 1160 \f[R] 1161 .fi 1162 .PP 1163 The compiler generates a warning for the \f[CB]finally\f[R] block in this 1164 example. 1165 When the \f[CB]int\f[R] method is called, it returns a value of 0. 1166 A \f[CB]finally\f[R] block executes when the \f[CB]try\f[R] block exits. 1167 In this example, when control is transferred to the \f[CB]catch\f[R] 1168 block, the \f[CB]int\f[R] method exits. 1169 However, the \f[CB]finally\f[R] block must execute, so it\[aq]s executed, 1170 even though control was transferred outside the method. 1171 .RE 1172 .TP 1173 .B \f[CB]options\f[R] 1174 Warns about issues that related to the use of command\-line options. 1175 See \f[B]Cross\-Compilation Options for javac\f[R]. 1176 .RS 1177 .RE 1178 .TP 1179 .B \f[CB]overrides\f[R] 1180 Warns about issues related to method overrides. 1181 For example, consider the following two classes: 1182 .RS 1183 .IP 1184 .nf 1185 \f[CB] 1186 public\ class\ ClassWithVarargsMethod\ { 1187 \ \ void\ varargsMethod(String...\ s)\ {\ } 1188 } 1189 1190 public\ class\ ClassWithOverridingMethod\ extends\ ClassWithVarargsMethod\ { 1191 \ \ \ \@Override 1192 \ \ \ void\ varargsMethod(String[]\ s)\ {\ } 1193 } 1194 \f[R] 1195 .fi 1196 .PP 1197 The compiler generates a warning similar to the following:. 1198 .IP 1199 .nf 1200 \f[CB] 1201 warning:\ [override]\ varargsMethod(String[])\ in\ ClassWithOverridingMethod 1202 overrides\ varargsMethod(String...)\ in\ ClassWithVarargsMethod;\ overriding 1203 method\ is\ missing\ \[aq]...\[aq] 1204 \f[R] 1205 .fi 1206 .PP 1207 When the compiler encounters a \f[CB]varargs\f[R] method, it translates 1208 the \f[CB]varargs\f[R] formal parameter into an array. 1209 In the method \f[CB]ClassWithVarargsMethod.varargsMethod\f[R], the 1210 compiler translates the \f[CB]varargs\f[R] formal parameter 1211 \f[CB]String...\ s\f[R] to the formal parameter \f[CB]String[]\ s\f[R], an 1212 array that matches the formal parameter of the method 1213 \f[CB]ClassWithOverridingMethod.varargsMethod\f[R]. 1214 Consequently, this example compiles. 1215 .RE 1216 .TP 1217 .B \f[CB]path\f[R] 1218 Warns about invalid path elements and nonexistent path directories on 1219 the command line (with regard to the class path, the source path, and 1220 other paths). 1221 Such warnings can\[aq]t be suppressed with the 1222 \f[CB]\@SuppressWarnings\f[R] annotation. 1223 For example: 1224 .RS 1225 .IP \[bu] 2 1226 \f[B]Oracle Solaris, Linux, and OS X:\f[R] 1227 \f[CB]javac\ \-Xlint:path\ \-classpath\ /nonexistentpath\ Example.java\f[R] 1228 .IP \[bu] 2 1229 \f[B]Windows:\f[R] 1230 \f[CB]javac\ \-Xlint:path\ \-classpath\ C:\\nonexistentpath\ Example.java\f[R] 1231 .RE 1232 .TP 1233 .B \f[CB]processing\f[R] 1234 Warns about issues related to annotation processing. 1235 The compiler generates this warning when you have a class that has an 1236 annotation, and you use an annotation processor that can\[aq]t handle 1237 that type of exception. 1238 For example, the following is a simple annotation processor: 1239 .RS 1240 .PP 1241 \f[B]Source file AnnocProc.java\f[R]: 1242 .IP 1243 .nf 1244 \f[CB] 1245 import\ java.util.*; 1246 import\ javax.annotation.processing.*; 1247 import\ javax.lang.model.*; 1248 import\ javaz.lang.model.element.*; 1249 1250 \@SupportedAnnotationTypes("NotAnno") 1251 public\ class\ AnnoProc\ extends\ AbstractProcessor\ { 1252 \ \ public\ boolean\ process(Set<?\ extends\ TypeElement>\ elems,\ RoundEnvironment\ renv){ 1253 \ \ \ \ \ return\ true; 1254 \ \ } 1255 1256 \ \ public\ SourceVersion\ getSupportedSourceVersion()\ { 1257 \ \ \ \ \ return\ SourceVersion.latest(); 1258 \ \ \ } 1259 } 1260 \f[R] 1261 .fi 1262 .PP 1263 \f[B]Source file AnnosWithoutProcessors.java\f[R]: 1264 .IP 1265 .nf 1266 \f[CB] 1267 \@interface\ Anno\ {\ } 1268 1269 \@Anno 1270 class\ AnnosWithoutProcessors\ {\ } 1271 \f[R] 1272 .fi 1273 .PP 1274 The following commands compile the annotation processor 1275 \f[CB]AnnoProc\f[R], then run this annotation processor against the source 1276 file \f[CB]AnnosWithoutProcessors.java\f[R]: 1277 .IP 1278 .nf 1279 \f[CB] 1280 javac\ AnnoProc.java 1281 javac\ \-cp\ .\ \-Xlint:processing\ \-processor\ AnnoProc\ \-proc:only\ AnnosWithoutProcessors.java 1282 \f[R] 1283 .fi 1284 .PP 1285 When the compiler runs the annotation processor against the source file 1286 \f[CB]AnnosWithoutProcessors.java\f[R], it generates the following 1287 warning: 1288 .IP 1289 .nf 1290 \f[CB] 1291 warning:\ [processing]\ No\ processor\ claimed\ any\ of\ these\ annotations:\ Anno 1292 \f[R] 1293 .fi 1294 .PP 1295 To resolve this issue, you can rename the annotation defined and used in 1296 the class \f[CB]AnnosWithoutProcessors\f[R] from \f[CB]Anno\f[R] to 1297 \f[CB]NotAnno\f[R]. 1298 .RE 1299 .TP 1300 .B \f[CB]rawtypes\f[R] 1301 Warns about unchecked operations on raw types. 1302 The following statement generates a \f[CB]rawtypes\f[R] warning: 1303 .RS 1304 .RS 1305 .PP 1306 \f[CB]void\ countElements(List\ l)\ {\ ...\ }\f[R] 1307 .RE 1308 .PP 1309 The following example doesn\[aq]t generate a \f[CB]rawtypes\f[R] warning: 1310 .RS 1311 .PP 1312 \f[CB]void\ countElements(List<?>\ l)\ {\ ...\ }\f[R] 1313 .RE 1314 .PP 1315 \f[CB]List\f[R] is a raw type. 1316 However, \f[CB]List<?>\f[R] is an unbounded wildcard parameterized type. 1317 Because \f[CB]List\f[R] is a parameterized interface, always specify its 1318 type argument. 1319 In this example, the \f[CB]List\f[R] formal argument is specified with an 1320 unbounded wildcard (\f[CB]?\f[R]) as its formal type parameter, which 1321 means that the \f[CB]countElements\f[R] method can accept any 1322 instantiation of the \f[CB]List\f[R] interface. 1323 .RE 1324 .TP 1325 .B \f[CB]serial\f[R] 1326 Warns about missing \f[CB]serialVersionUID\f[R] definitions on 1327 serializable classes. 1328 For example: 1329 .RS 1330 .IP 1331 .nf 1332 \f[CB] 1333 public\ class\ PersistentTime\ implements\ Serializable 1334 { 1335 \ \ private\ Date\ time; 1336 1337 \ \ \ public\ PersistentTime()\ { 1338 \ \ \ \ \ time\ =\ Calendar.getInstance().getTime(); 1339 \ \ \ } 1340 1341 \ \ \ public\ Date\ getTime()\ { 1342 \ \ \ \ \ return\ time; 1343 \ \ \ } 1344 } 1345 \f[R] 1346 .fi 1347 .PP 1348 The compiler generates the following warning: 1349 .IP 1350 .nf 1351 \f[CB] 1352 warning:\ [serial]\ serializable\ class\ PersistentTime\ has\ no\ definition\ of 1353 serialVersionUID 1354 \f[R] 1355 .fi 1356 .PP 1357 If a serializable class doesn\[aq]t explicitly declare a field named 1358 \f[CB]serialVersionUID\f[R], then the serialization runtime environment 1359 calculates a default \f[CB]serialVersionUID\f[R] value for that class 1360 based on various aspects of the class, as described in the Java Object 1361 Serialization Specification. 1362 However, it\[aq]s strongly recommended that all serializable classes 1363 explicitly declare \f[CB]serialVersionUID\f[R] values because the default 1364 process of computing \f[CB]serialVersionUID\f[R] values is highly 1365 sensitive to class details that can vary depending on compiler 1366 implementations. 1367 As a result, this might cause an unexpected 1368 \f[CB]InvalidClassExceptions\f[R] during deserialization. 1369 To guarantee a consistent \f[CB]serialVersionUID\f[R] value across 1370 different Java compiler implementations, a serializable class must 1371 declare an explicit \f[CB]serialVersionUID\f[R] value. 1372 .RE 1373 .TP 1374 .B \f[CB]static\f[R] 1375 Warns about issues relating to the use of statics variables, for 1376 example: 1377 .RS 1378 .IP 1379 .nf 1380 \f[CB] 1381 class\ XLintStatic\ { 1382 \ \ \ \ static\ void\ m1()\ {\ } 1383 \ \ \ \ void\ m2()\ {\ this.m1();\ } 1384 } 1385 \f[R] 1386 .fi 1387 .PP 1388 The compiler generates the following warning: 1389 .IP 1390 .nf 1391 \f[CB] 1392 warning:\ [static]\ static\ method\ should\ be\ qualified\ by\ type\ name, 1393 XLintStatic,\ instead\ of\ by\ an\ expression 1394 \f[R] 1395 .fi 1396 .PP 1397 To resolve this issue, you can call the \f[CB]static\f[R] method 1398 \f[CB]m1\f[R] as follows: 1399 .RS 1400 .PP 1401 \f[CB]XLintStatic.m1();\f[R] 1402 .RE 1403 .PP 1404 Alternately, you can remove the \f[CB]static\f[R] keyword from the 1405 declaration of the method \f[CB]m1\f[R]. 1406 .RE 1407 .TP 1408 .B \f[CB]try\f[R] 1409 Warns about issues relating to the use of \f[CB]try\f[R] blocks, including 1410 try\-with\-resources statements. 1411 For example, a warning is generated for the following statement because 1412 the resource \f[CB]ac\f[R] declared in the \f[CB]try\f[R] block isn\[aq]t 1413 used: 1414 .RS 1415 .IP 1416 .nf 1417 \f[CB] 1418 try\ (\ AutoCloseable\ ac\ =\ getResource()\ )\ {\ \ \ \ //\ do\ nothing} 1419 \f[R] 1420 .fi 1421 .RE 1422 .TP 1423 .B \f[CB]unchecked\f[R] 1424 Gives more detail for unchecked conversion warnings that are mandated by 1425 the Java Language Specification, for example: 1426 .RS 1427 .IP 1428 .nf 1429 \f[CB] 1430 List\ l\ =\ new\ ArrayList<Number>(); 1431 List<String>\ ls\ =\ l;\ \ \ \ \ \ \ //\ unchecked\ warning 1432 \f[R] 1433 .fi 1434 .PP 1435 During type erasure, the types \f[CB]ArrayList<Number>\f[R] and 1436 \f[CB]List<String>\f[R] become \f[CB]ArrayList\f[R] and \f[CB]List\f[R], 1437 respectively. 1438 .PP 1439 The \f[CB]ls\f[R] command has the parameterized type 1440 \f[CB]List<String>\f[R]. 1441 When the \f[CB]List\f[R] referenced by \f[CB]l\f[R] is assigned to 1442 \f[CB]ls\f[R], the compiler generates an unchecked warning. 1443 At compile time, the compiler and JVM can\[aq]t determine whether 1444 \f[CB]l\f[R] refers to a \f[CB]List<String>\f[R] type. 1445 In this case, \f[CB]l\f[R] doesn\[aq]t refer to a \f[CB]List<String>\f[R] 1446 type. 1447 As a result, heap pollution occurs. 1448 .PP 1449 A heap pollution situation occurs when the \f[CB]List\f[R] object 1450 \f[CB]l\f[R], whose static type is \f[CB]List<Number>\f[R], is assigned to 1451 another \f[CB]List\f[R] object, \f[CB]ls\f[R], that has a different static 1452 type, \f[CB]List<String>\f[R]. 1453 However, the compiler still allows this assignment. 1454 It must allow this assignment to preserve backward compatibility with 1455 releases of Java SE that don\[aq]t support generics. 1456 Because of type erasure, \f[CB]List<Number>\f[R] and \f[CB]List<String>\f[R] 1457 both become \f[CB]List\f[R]. 1458 Consequently, the compiler allows the assignment of the object 1459 \f[CB]l\f[R], which has a raw type of \f[CB]List\f[R], to the object 1460 \f[CB]ls\f[R]. 1461 .RE 1462 .TP 1463 .B \f[CB]varargs\f[R] 1464 Warns about unsafe use of variable arguments (\f[CB]varargs\f[R]) methods, 1465 in particular, those that contain non\-reifiable arguments, for example: 1466 .RS 1467 .IP 1468 .nf 1469 \f[CB] 1470 public\ class\ ArrayBuilder\ { 1471 \ \ public\ static\ <T>\ void\ addToList\ (List<T>\ listArg,\ T...\ elements)\ { 1472 \ \ \ \ for\ (T\ x\ :\ elements)\ { 1473 \ \ \ \ \ \ listArg.add(x); 1474 \ \ \ \ } 1475 \ \ } 1476 } 1477 \f[R] 1478 .fi 1479 .PP 1480 A non\-reifiable type is a type whose type information isn\[aq]t fully 1481 available at runtime. 1482 .PP 1483 The compiler generates the following warning for the definition of the 1484 method \f[CB]ArrayBuilder.addToList\f[R]: 1485 .IP 1486 .nf 1487 \f[CB] 1488 warning:\ [varargs]\ Possible\ heap\ pollution\ from\ parameterized\ vararg\ type\ T 1489 \f[R] 1490 .fi 1491 .PP 1492 When the compiler encounters a varargs method, it translates the 1493 \f[CB]varargs\f[R] formal parameter into an array. 1494 However, the Java programming language doesn\[aq]t permit the creation 1495 of arrays of parameterized types. 1496 In the method \f[CB]ArrayBuilder.addToList\f[R], the compiler translates 1497 the \f[CB]varargs\f[R] formal parameter \f[CB]T...\f[R] elements to the 1498 formal parameter \f[CB]T[]\f[R] elements, an array. 1499 However, because of type erasure, the compiler converts the 1500 \f[CB]varargs\f[R] formal parameter to \f[CB]Object[]\f[R] elements. 1501 Consequently, there\[aq]s a possibility of heap pollution. 1502 .RE 1503 .SH EXAMPLE OF COMPILING BY PROVIDING COMMAND\-LINE ARGUMENTS 1504 .PP 1505 To compile as though providing command\-line arguments, use the 1506 following syntax: 1507 .RS 1508 .PP 1509 \f[CB]JavaCompiler\ javac\ =\ ToolProvider.getSystemJavaCompiler();\f[R] 1510 .RE 1511 .PP 1512 The example writes diagnostics to the standard output stream and returns 1513 the exit code that \f[CB]javac\f[R] command would give when called from 1514 the command line. 1515 .PP 1516 You can use other methods in the \f[CB]javax.tools.JavaCompiler\f[R] 1517 interface to handle diagnostics, control where files are read from and 1518 written to, and more. 1519 .SH OLD INTERFACE 1520 .PP 1521 \f[B]Note:\f[R] 1522 .PP 1523 This API is retained for backward compatibility only. 1524 All new code should use the Java Compiler API. 1525 .PP 1526 The \f[CB]com.sun.tools.javac.Main\f[R] class provides two static methods 1527 to call the compiler from a program: 1528 .IP 1529 .nf 1530 \f[CB] 1531 public\ static\ int\ compile(String[]\ args); 1532 public\ static\ int\ compile(String[]\ args,\ PrintWriter\ out); 1533 \f[R] 1534 .fi 1535 .PP 1536 The \f[CB]args\f[R] parameter represents any of the command\-line 1537 arguments that would typically be passed to the compiler. 1538 .PP 1539 The \f[CB]out\f[R] parameter indicates where the compiler diagnostic 1540 output is directed. 1541 .PP 1542 The \f[CB]return\f[R] value is equivalent to the \f[CB]exit\f[R] value from 1543 \f[CB]javac\f[R]. 1544 .PP 1545 \f[B]Note:\f[R] 1546 .PP 1547 All other classes and methods found in a package with names that start 1548 with \f[CB]com.sun.tools.javac\f[R] (subpackages of 1549 \f[CB]com.sun.tools.javac\f[R]) are strictly internal and subject to 1550 change at any time. 1551 .SH EXAMPLE OF COMPILING MULTIPLE SOURCE FILES 1552 .PP 1553 This example compiles the \f[CB]Aloha.java\f[R], \f[CB]GutenTag.java\f[R], 1554 \f[CB]Hello.java\f[R], and \f[CB]Hi.java\f[R] source files in the 1555 \f[CB]greetings\f[R] package. 1556 .PP 1557 \f[B]Oracle Solaris, Linux, and OS X:\f[R] 1558 .IP 1559 .nf 1560 \f[CB] 1561 %\ javac\ greetings/*.java 1562 %\ ls\ greetings 1563 Aloha.class\ \ \ \ \ \ \ \ \ GutenTag.class\ \ \ \ \ \ Hello.class\ \ \ \ \ \ \ \ \ Hi.class 1564 Aloha.java\ \ \ \ \ \ \ \ \ \ GutenTag.java\ \ \ \ \ \ \ Hello.java\ \ \ \ \ \ \ \ \ \ Hi.java 1565 \f[R] 1566 .fi 1567 .PP 1568 \f[B]Windows:\f[R] 1569 .IP 1570 .nf 1571 \f[CB] 1572 C:\\>javac\ greetings\\*.java 1573 C:\\>dir\ greetings 1574 Aloha.class\ \ \ \ \ \ \ \ \ GutenTag.class\ \ \ \ \ \ Hello.class\ \ \ \ \ \ \ \ \ Hi.class 1575 Aloha.java\ \ \ \ \ \ \ \ \ \ GutenTag.java\ \ \ \ \ \ \ Hello.java\ \ \ \ \ \ \ \ \ \ Hi.java 1576 \f[R] 1577 .fi 1578 .SH EXAMPLE OF SPECIFYING A USER CLASS PATH 1579 .PP 1580 After changing one of the source files in the previous example, 1581 recompile it: 1582 .PP 1583 \f[B]Oracle Solaris, Linux, and OS X:\f[R] 1584 .IP 1585 .nf 1586 \f[CB] 1587 pwd 1588 /examples 1589 javac\ greetings/Hi.java 1590 \f[R] 1591 .fi 1592 .PP 1593 \f[B]Windows:\f[R] 1594 .IP 1595 .nf 1596 \f[CB] 1597 C:\\>cd 1598 \\examples 1599 C:\\>javac\ greetings\\Hi.java 1600 \f[R] 1601 .fi 1602 .PP 1603 Because \f[CB]greetings.Hi\f[R] refers to other classes in the 1604 \f[CB]greetings\f[R] package, the compiler needs to find these other 1605 classes. 1606 The previous example works because the default user class path is the 1607 directory that contains the package directory. 1608 If you want to recompile this file without concern for which directory 1609 you are in, then add the examples directory to the user class path by 1610 setting \f[CB]CLASSPATH\f[R]. 1611 This example uses the \f[CB]\-classpath\f[R] option. 1612 .PP 1613 \f[B]Oracle Solaris, Linux, and OS X:\f[R] 1614 .RS 1615 .PP 1616 \f[CB]javac\ \-classpath\ /examples\ /examples/greetings/Hi.java\f[R] 1617 .RE 1618 .PP 1619 \f[B]Windows:\f[R] 1620 .RS 1621 .PP 1622 \f[CB]C:\\>javac\ \-classpath\ \\examples\ \\examples\\greetings\\Hi.java\f[R] 1623 .RE 1624 .PP 1625 If you change \f[CB]greetings.Hi\f[R] to use a banner utility, then that 1626 utility also needs to be accessible through the user class path. 1627 .PP 1628 \f[B]Oracle Solaris, Linux, and OS X:\f[R] 1629 .IP 1630 .nf 1631 \f[CB] 1632 javac\ \-classpath\ /examples:/lib/Banners.jar\ \\ 1633 \ \ \ \ \ \ \ \ \ \ \ \ /examples/greetings/Hi.java 1634 \f[R] 1635 .fi 1636 .PP 1637 \f[B]Windows:\f[R] 1638 .IP 1639 .nf 1640 \f[CB] 1641 C:\\>javac\ \-classpath\ \\examples;\\lib\\Banners.jar\ ^ 1642 \ \ \ \ \ \ \ \ \ \ \ \ \\examples\\greetings\\Hi.java 1643 \f[R] 1644 .fi 1645 .PP 1646 To execute a class in the \f[CB]greetings\f[R] package, the program needs 1647 access to the \f[CB]greetings\f[R] package, and to the classes that the 1648 \f[CB]greetings\f[R] classes use. 1649 .PP 1650 \f[B]Oracle Solaris, Linux, and OS X:\f[R] 1651 .RS 1652 .PP 1653 \f[CB]java\ \-classpath\ /examples:/lib/Banners.jar\ greetings.Hi\f[R] 1654 .RE 1655 .PP 1656 \f[B]Windows:\f[R] 1657 .RS 1658 .PP 1659 \f[CB]C:\\>java\ \-classpath\ \\examples;\\lib\\Banners.jar\ greetings.Hi\f[R] 1660 .RE 1661 .PP 1662 The \f[CB]\-source\ 1.7\f[R] option specifies that release 1.7 (or 7) of 1663 the Java programming language must be used to compile OldCode.java. 1664 The \f[CB]\-target\ 1.7\f[R] option ensures that the generated class files 1665 are compatible with JVM 1.7. 1666 .SH ANNOTATION PROCESSING 1667 .PP 1668 The \f[CB]javac\f[R] command provides direct support for annotation 1669 processing, superseding the need for the separate annotation processing 1670 command, \f[CB]apt\f[R]. 1671 .PP 1672 The API for annotation processors is defined in the 1673 \f[CB]javax.annotation.processing\f[R] and \f[CB]javax.lang.model\f[R] 1674 packages and subpackages. 1675 .SS How Annotation Processing Works 1676 .PP 1677 Unless annotation processing is disabled with the \f[CB]\-proc:none\f[R] 1678 option, the compiler searches for any annotation processors that are 1679 available. 1680 The search path can be specified with the \f[CB]\-processorpath\f[R] 1681 option. 1682 If no path is specified, then the user class path is used. 1683 Processors are located by means of service provider\-configuration files 1684 named \f[CB]META\-INF/services/javax.annotation.processing\f[R]. 1685 Processor on the search path. 1686 Such files should contain the names of any annotation processors to be 1687 used, listed one per line. 1688 Alternatively, processors can be specified explicitly, using the 1689 \f[CB]\-processor\f[R] option. 1690 .PP 1691 After scanning the source files and classes on the command line to 1692 determine what annotations are present, the compiler queries the 1693 processors to determine what annotations they process. 1694 When a match is found, the processor is called. 1695 A processor can claim the annotations it processes, in which case no 1696 further attempt is made to find any processors for those annotations. 1697 After all of the annotations are claimed, the compiler does not search 1698 for additional processors. 1699 .PP 1700 If any processors generate new source files, then another round of 1701 annotation processing occurs: Any newly generated source files are 1702 scanned, and the annotations processed as before. 1703 Any processors called on previous rounds are also called on all 1704 subsequent rounds. 1705 This continues until no new source files are generated. 1706 .PP 1707 After a round occurs where no new source files are generated, the 1708 annotation processors are called one last time, to give them a chance to 1709 complete any remaining work. 1710 Finally, unless the \f[CB]\-proc:only\f[R] option is used, the compiler 1711 compiles the original and all generated source files. 1712 .SH SEARCHING FOR TYPES 1713 .PP 1714 To compile a source file, the compiler often needs information about a 1715 type, but the type definition is not in the source files specified on 1716 the command line. 1717 .PP 1718 The compiler needs type information for every class or interface used, 1719 extended, or implemented in the source file. 1720 This includes classes and interfaces not explicitly mentioned in the 1721 source file, but that provide information through inheritance. 1722 .PP 1723 For example, when you create a subclass of \f[CB]java.awt.Window\f[R], you 1724 are also using the ancestor classes of \f[CB]Window\f[R]: 1725 \f[CB]java.awt.Container\f[R], \f[CB]java.awt.Component\f[R], and 1726 \f[CB]java.lang.Object\f[R]. 1727 .PP 1728 When the compiler needs type information, it searches for a source file 1729 or class file that defines the type. 1730 The compiler searches for class files first in the bootstrap and 1731 extension classes, then in the user class path (which by default is the 1732 current directory). 1733 The user class path is defined by setting the \f[CB]CLASSPATH\f[R] 1734 environment variable or by using the \f[CB]\-classpath\f[R] option. 1735 .PP 1736 If you set the \f[CB]\-sourcepath\f[R] option, then the compiler searches 1737 the indicated path for source files. 1738 Otherwise, the compiler searches the user class path for both class 1739 files and source files. 1740 .PP 1741 You can specify different bootstrap or extension classes with the 1742 \f[CB]\-bootclasspath\f[R] and the \f[CB]\-extdirs\f[R] options. 1743 See \f[B]Cross\-Compilation Options for javac\f[R]. 1744 .PP 1745 A successful type search may produce a class file, a source file, or 1746 both. 1747 If both are found, then you can use the \f[CB]\-Xprefer\f[R] option to 1748 instruct the compiler which to use. 1749 If \f[CB]newer\f[R] is specified, then the compiler uses the newer of the 1750 two files. 1751 If \f[CB]source\f[R] is specified, the compiler uses the source file. 1752 The default is \f[CB]newer\f[R]. 1753 .PP 1754 If a type search finds a source file for a required type, either by 1755 itself, or as a result of the setting for the \f[CB]\-Xprefer\f[R] option, 1756 then the compiler reads the source file to get the information it needs. 1757 By default the compiler also compiles the source file. 1758 You can use the \f[CB]\-implicit\f[R] option to specify the behavior. 1759 If \f[CB]none\f[R] is specified, then no class files are generated for the 1760 source file. 1761 If \f[CB]class\f[R] is specified, then class files are generated for the 1762 source file. 1763 .PP 1764 The compiler might not discover the need for some type information until 1765 after annotation processing completes. 1766 When the type information is found in a source file and no 1767 \f[CB]\-implicit\f[R] option is specified, the compiler gives a warning 1768 that the file is being compiled without being subject to annotation 1769 processing. 1770 To disable the warning, either specify the file on the command line (so 1771 that it will be subject to annotation processing) or use the 1772 \f[CB]\-implicit\f[R] option to specify whether or not class files should 1773 be generated for such source files.