1 /*
2 * Copyright (c) 1996, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.io;
27
28 import java.util.Objects;
29 import java.util.Formatter;
30 import java.util.Locale;
31 import java.nio.charset.Charset;
32 import java.nio.charset.IllegalCharsetNameException;
33 import java.nio.charset.UnsupportedCharsetException;
34
35 /**
36 * Prints formatted representations of objects to a text-output stream. This
37 * class implements all of the <tt>print</tt> methods found in {@link
38 * PrintStream}. It does not contain methods for writing raw bytes, for which
39 * a program should use unencoded byte streams.
40 *
41 * <p> Unlike the {@link PrintStream} class, if automatic flushing is enabled
42 * it will be done only when one of the <tt>println</tt>, <tt>printf</tt>, or
43 * <tt>format</tt> methods is invoked, rather than whenever a newline character
44 * happens to be output. These methods use the platform's own notion of line
45 * separator rather than the newline character.
46 *
47 * <p> Methods in this class never throw I/O exceptions, although some of its
48 * constructors may. The client may inquire as to whether any errors have
49 * occurred by invoking {@link #checkError checkError()}.
50 *
51 * @author Frank Yellin
52 * @author Mark Reinhold
53 * @since 1.1
54 */
55
56 public class PrintWriter extends Writer {
57
58 /**
59 * The underlying character-output stream of this
60 * <code>PrintWriter</code>.
61 *
62 * @since 1.2
63 */
64 protected Writer out;
65
66 private final boolean autoFlush;
67 private boolean trouble = false;
68 private Formatter formatter;
69 private PrintStream psOut = null;
70
71 /**
72 * Returns a charset object for the given charset name.
73 * @throws NullPointerException is csn is null
74 * @throws UnsupportedEncodingException if the charset is not supported
75 */
76 private static Charset toCharset(String csn)
77 throws UnsupportedEncodingException
78 {
79 Objects.requireNonNull(csn, "charsetName");
80 try {
81 return Charset.forName(csn);
82 } catch (IllegalCharsetNameException|UnsupportedCharsetException unused) {
83 // UnsupportedEncodingException should be thrown
84 throw new UnsupportedEncodingException(csn);
85 }
86 }
87
88 /**
89 * Creates a new PrintWriter, without automatic line flushing.
90 *
91 * @param out A character-output stream
92 */
93 public PrintWriter (Writer out) {
94 this(out, false);
95 }
96
97 /**
98 * Creates a new PrintWriter.
99 *
100 * @param out A character-output stream
101 * @param autoFlush A boolean; if true, the <tt>println</tt>,
102 * <tt>printf</tt>, or <tt>format</tt> methods will
103 * flush the output buffer
104 */
105 public PrintWriter(Writer out,
106 boolean autoFlush) {
107 super(out);
108 this.out = out;
109 this.autoFlush = autoFlush;
110 }
111
112 /**
113 * Creates a new PrintWriter, without automatic line flushing, from an
114 * existing OutputStream. This convenience constructor creates the
115 * necessary intermediate OutputStreamWriter, which will convert characters
116 * into bytes using the default character encoding.
117 *
118 * @param out An output stream
119 *
120 * @see java.io.OutputStreamWriter#OutputStreamWriter(java.io.OutputStream)
121 */
122 public PrintWriter(OutputStream out) {
123 this(out, false);
124 }
125
126 /**
127 * Creates a new PrintWriter from an existing OutputStream. This
128 * convenience constructor creates the necessary intermediate
129 * OutputStreamWriter, which will convert characters into bytes using the
130 * default character encoding.
131 *
132 * @param out An output stream
133 * @param autoFlush A boolean; if true, the <tt>println</tt>,
134 * <tt>printf</tt>, or <tt>format</tt> methods will
135 * flush the output buffer
136 *
137 * @see java.io.OutputStreamWriter#OutputStreamWriter(java.io.OutputStream)
138 */
139 public PrintWriter(OutputStream out, boolean autoFlush) {
140 this(new BufferedWriter(new OutputStreamWriter(out)), autoFlush);
141
142 // save print stream for error propagation
143 if (out instanceof java.io.PrintStream) {
144 psOut = (PrintStream) out;
145 }
146 }
147
148 /**
149 * Creates a new PrintWriter, without automatic line flushing, with the
150 * specified file name. This convenience constructor creates the necessary
151 * intermediate {@link java.io.OutputStreamWriter OutputStreamWriter},
152 * which will encode characters using the {@linkplain
153 * java.nio.charset.Charset#defaultCharset() default charset} for this
154 * instance of the Java virtual machine.
155 *
156 * @param fileName
157 * The name of the file to use as the destination of this writer.
158 * If the file exists then it will be truncated to zero size;
159 * otherwise, a new file will be created. The output will be
160 * written to the file and is buffered.
161 *
162 * @throws FileNotFoundException
163 * If the given string does not denote an existing, writable
164 * regular file and a new regular file of that name cannot be
165 * created, or if some other error occurs while opening or
166 * creating the file
167 *
168 * @throws SecurityException
169 * If a security manager is present and {@link
170 * SecurityManager#checkWrite checkWrite(fileName)} denies write
171 * access to the file
172 *
173 * @since 1.5
174 */
175 public PrintWriter(String fileName) throws FileNotFoundException {
176 this(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(fileName))),
177 false);
178 }
179
180 /* Private constructor */
181 private PrintWriter(Charset charset, File file)
182 throws FileNotFoundException
183 {
184 this(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file), charset)),
185 false);
186 }
187
188 /**
189 * Creates a new PrintWriter, without automatic line flushing, with the
190 * specified file name and charset. This convenience constructor creates
191 * the necessary intermediate {@link java.io.OutputStreamWriter
192 * OutputStreamWriter}, which will encode characters using the provided
193 * charset.
194 *
195 * @param fileName
196 * The name of the file to use as the destination of this writer.
197 * If the file exists then it will be truncated to zero size;
198 * otherwise, a new file will be created. The output will be
199 * written to the file and is buffered.
200 *
201 * @param csn
202 * The name of a supported {@linkplain java.nio.charset.Charset
203 * charset}
204 *
205 * @throws FileNotFoundException
206 * If the given string does not denote an existing, writable
207 * regular file and a new regular file of that name cannot be
208 * created, or if some other error occurs while opening or
209 * creating the file
210 *
211 * @throws SecurityException
212 * If a security manager is present and {@link
213 * SecurityManager#checkWrite checkWrite(fileName)} denies write
214 * access to the file
215 *
216 * @throws UnsupportedEncodingException
217 * If the named charset is not supported
218 *
219 * @since 1.5
220 */
221 public PrintWriter(String fileName, String csn)
222 throws FileNotFoundException, UnsupportedEncodingException
223 {
224 this(toCharset(csn), new File(fileName));
225 }
226
227 /**
228 * Creates a new PrintWriter, without automatic line flushing, with the
229 * specified file. This convenience constructor creates the necessary
230 * intermediate {@link java.io.OutputStreamWriter OutputStreamWriter},
231 * which will encode characters using the {@linkplain
232 * java.nio.charset.Charset#defaultCharset() default charset} for this
233 * instance of the Java virtual machine.
234 *
235 * @param file
236 * The file to use as the destination of this writer. If the file
237 * exists then it will be truncated to zero size; otherwise, a new
238 * file will be created. The output will be written to the file
239 * and is buffered.
240 *
241 * @throws FileNotFoundException
242 * If the given file object does not denote an existing, writable
243 * regular file and a new regular file of that name cannot be
244 * created, or if some other error occurs while opening or
245 * creating the file
246 *
247 * @throws SecurityException
248 * If a security manager is present and {@link
249 * SecurityManager#checkWrite checkWrite(file.getPath())}
250 * denies write access to the file
251 *
252 * @since 1.5
253 */
254 public PrintWriter(File file) throws FileNotFoundException {
255 this(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file))),
256 false);
257 }
258
259 /**
260 * Creates a new PrintWriter, without automatic line flushing, with the
261 * specified file and charset. This convenience constructor creates the
262 * necessary intermediate {@link java.io.OutputStreamWriter
263 * OutputStreamWriter}, which will encode characters using the provided
264 * charset.
265 *
266 * @param file
267 * The file to use as the destination of this writer. If the file
268 * exists then it will be truncated to zero size; otherwise, a new
269 * file will be created. The output will be written to the file
270 * and is buffered.
271 *
272 * @param csn
273 * The name of a supported {@linkplain java.nio.charset.Charset
274 * charset}
275 *
276 * @throws FileNotFoundException
277 * If the given file object does not denote an existing, writable
278 * regular file and a new regular file of that name cannot be
279 * created, or if some other error occurs while opening or
280 * creating the file
281 *
282 * @throws SecurityException
283 * If a security manager is present and {@link
284 * SecurityManager#checkWrite checkWrite(file.getPath())}
285 * denies write access to the file
286 *
287 * @throws UnsupportedEncodingException
288 * If the named charset is not supported
289 *
290 * @since 1.5
291 */
292 public PrintWriter(File file, String csn)
293 throws FileNotFoundException, UnsupportedEncodingException
294 {
295 this(toCharset(csn), file);
296 }
297
298 /** Checks to make sure that the stream has not been closed */
299 private void ensureOpen() throws IOException {
300 if (out == null)
301 throw new IOException("Stream closed");
302 }
303
304 /**
305 * Flushes the stream.
306 * @see #checkError()
307 */
308 public void flush() {
309 try {
310 synchronized (lock) {
311 ensureOpen();
312 out.flush();
313 }
314 }
315 catch (IOException x) {
316 trouble = true;
317 }
318 }
319
320 /**
321 * Closes the stream and releases any system resources associated
322 * with it. Closing a previously closed stream has no effect.
323 *
324 * @see #checkError()
325 */
326 public void close() {
327 try {
328 synchronized (lock) {
329 if (out == null)
330 return;
331 out.close();
332 out = null;
333 }
334 }
335 catch (IOException x) {
336 trouble = true;
337 }
338 }
339
340 /**
341 * Flushes the stream if it's not closed and checks its error state.
342 *
343 * @return <code>true</code> if the print stream has encountered an error,
344 * either on the underlying output stream or during a format
345 * conversion.
346 */
347 public boolean checkError() {
348 if (out != null) {
349 flush();
350 }
351 if (out instanceof java.io.PrintWriter) {
352 PrintWriter pw = (PrintWriter) out;
353 return pw.checkError();
354 } else if (psOut != null) {
355 return psOut.checkError();
356 }
357 return trouble;
358 }
359
360 /**
361 * Indicates that an error has occurred.
362 *
363 * <p> This method will cause subsequent invocations of {@link
364 * #checkError()} to return <tt>true</tt> until {@link
365 * #clearError()} is invoked.
366 */
367 protected void setError() {
368 trouble = true;
369 }
370
371 /**
372 * Clears the error state of this stream.
373 *
374 * <p> This method will cause subsequent invocations of {@link
375 * #checkError()} to return <tt>false</tt> until another write
376 * operation fails and invokes {@link #setError()}.
377 *
378 * @since 1.6
379 */
380 protected void clearError() {
381 trouble = false;
382 }
383
384 /*
385 * Exception-catching, synchronized output operations,
386 * which also implement the write() methods of Writer
387 */
388
389 /**
390 * Writes a single character.
391 * @param c int specifying a character to be written.
392 */
393 public void write(int c) {
394 try {
395 synchronized (lock) {
396 ensureOpen();
397 out.write(c);
398 }
399 }
400 catch (InterruptedIOException x) {
401 Thread.currentThread().interrupt();
402 }
403 catch (IOException x) {
404 trouble = true;
405 }
406 }
407
408 /**
409 * Writes A Portion of an array of characters.
410 * @param buf Array of characters
411 * @param off Offset from which to start writing characters
412 * @param len Number of characters to write
413 */
414 public void write(char buf[], int off, int len) {
415 try {
416 synchronized (lock) {
417 ensureOpen();
418 out.write(buf, off, len);
419 }
420 }
421 catch (InterruptedIOException x) {
422 Thread.currentThread().interrupt();
423 }
424 catch (IOException x) {
425 trouble = true;
426 }
427 }
428
429 /**
430 * Writes an array of characters. This method cannot be inherited from the
431 * Writer class because it must suppress I/O exceptions.
432 * @param buf Array of characters to be written
433 */
434 public void write(char buf[]) {
435 write(buf, 0, buf.length);
436 }
437
438 /**
439 * Writes a portion of a string.
440 * @param s A String
441 * @param off Offset from which to start writing characters
442 * @param len Number of characters to write
443 */
444 public void write(String s, int off, int len) {
445 try {
446 synchronized (lock) {
447 ensureOpen();
448 out.write(s, off, len);
449 }
450 }
451 catch (InterruptedIOException x) {
452 Thread.currentThread().interrupt();
453 }
454 catch (IOException x) {
455 trouble = true;
456 }
457 }
458
459 /**
460 * Writes a string. This method cannot be inherited from the Writer class
461 * because it must suppress I/O exceptions.
462 * @param s String to be written
463 */
464 public void write(String s) {
465 write(s, 0, s.length());
466 }
467
468 private void newLine() {
469 try {
470 synchronized (lock) {
471 ensureOpen();
472 out.write(System.lineSeparator());
473 if (autoFlush)
474 out.flush();
475 }
476 }
477 catch (InterruptedIOException x) {
478 Thread.currentThread().interrupt();
479 }
480 catch (IOException x) {
481 trouble = true;
482 }
483 }
484
485 /* Methods that do not terminate lines */
486
487 /**
488 * Prints a boolean value. The string produced by <code>{@link
489 * java.lang.String#valueOf(boolean)}</code> is translated into bytes
490 * according to the platform's default character encoding, and these bytes
491 * are written in exactly the manner of the <code>{@link
492 * #write(int)}</code> method.
493 *
494 * @param b The <code>boolean</code> to be printed
495 */
496 public void print(boolean b) {
497 write(b ? "true" : "false");
498 }
499
500 /**
501 * Prints a character. The character is translated into one or more bytes
502 * according to the platform's default character encoding, and these bytes
503 * are written in exactly the manner of the <code>{@link
504 * #write(int)}</code> method.
505 *
506 * @param c The <code>char</code> to be printed
507 */
508 public void print(char c) {
509 write(c);
510 }
511
512 /**
513 * Prints an integer. The string produced by <code>{@link
514 * java.lang.String#valueOf(int)}</code> is translated into bytes according
515 * to the platform's default character encoding, and these bytes are
516 * written in exactly the manner of the <code>{@link #write(int)}</code>
517 * method.
518 *
519 * @param i The <code>int</code> to be printed
520 * @see java.lang.Integer#toString(int)
521 */
522 public void print(int i) {
523 write(String.valueOf(i));
524 }
525
526 /**
527 * Prints a long integer. The string produced by <code>{@link
528 * java.lang.String#valueOf(long)}</code> is translated into bytes
529 * according to the platform's default character encoding, and these bytes
530 * are written in exactly the manner of the <code>{@link #write(int)}</code>
531 * method.
532 *
533 * @param l The <code>long</code> to be printed
534 * @see java.lang.Long#toString(long)
535 */
536 public void print(long l) {
537 write(String.valueOf(l));
538 }
539
540 /**
541 * Prints a floating-point number. The string produced by <code>{@link
542 * java.lang.String#valueOf(float)}</code> is translated into bytes
543 * according to the platform's default character encoding, and these bytes
544 * are written in exactly the manner of the <code>{@link #write(int)}</code>
545 * method.
546 *
547 * @param f The <code>float</code> to be printed
548 * @see java.lang.Float#toString(float)
549 */
550 public void print(float f) {
551 write(String.valueOf(f));
552 }
553
554 /**
555 * Prints a double-precision floating-point number. The string produced by
556 * <code>{@link java.lang.String#valueOf(double)}</code> is translated into
557 * bytes according to the platform's default character encoding, and these
558 * bytes are written in exactly the manner of the <code>{@link
559 * #write(int)}</code> method.
560 *
561 * @param d The <code>double</code> to be printed
562 * @see java.lang.Double#toString(double)
563 */
564 public void print(double d) {
565 write(String.valueOf(d));
566 }
567
568 /**
569 * Prints an array of characters. The characters are converted into bytes
570 * according to the platform's default character encoding, and these bytes
571 * are written in exactly the manner of the <code>{@link #write(int)}</code>
572 * method.
573 *
574 * @param s The array of chars to be printed
575 *
576 * @throws NullPointerException If <code>s</code> is <code>null</code>
577 */
578 public void print(char s[]) {
579 write(s);
580 }
581
582 /**
583 * Prints a string. If the argument is <code>null</code> then the string
584 * <code>"null"</code> is printed. Otherwise, the string's characters are
585 * converted into bytes according to the platform's default character
586 * encoding, and these bytes are written in exactly the manner of the
587 * <code>{@link #write(int)}</code> method.
588 *
589 * @param s The <code>String</code> to be printed
590 */
591 public void print(String s) {
592 if (s == null) {
593 s = "null";
594 }
595 write(s);
596 }
597
598 /**
599 * Prints an object. The string produced by the <code>{@link
600 * java.lang.String#valueOf(Object)}</code> method is translated into bytes
601 * according to the platform's default character encoding, and these bytes
602 * are written in exactly the manner of the <code>{@link #write(int)}</code>
603 * method.
604 *
605 * @param obj The <code>Object</code> to be printed
606 * @see java.lang.Object#toString()
607 */
608 public void print(Object obj) {
609 write(String.valueOf(obj));
610 }
611
612 /* Methods that do terminate lines */
613
614 /**
615 * Terminates the current line by writing the line separator string. The
616 * line separator string is defined by the system property
617 * <code>line.separator</code>, and is not necessarily a single newline
618 * character (<code>'\n'</code>).
619 */
620 public void println() {
621 newLine();
622 }
623
624 /**
625 * Prints a boolean value and then terminates the line. This method behaves
626 * as though it invokes <code>{@link #print(boolean)}</code> and then
627 * <code>{@link #println()}</code>.
628 *
629 * @param x the <code>boolean</code> value to be printed
630 */
631 public void println(boolean x) {
632 synchronized (lock) {
633 print(x);
634 println();
635 }
636 }
637
638 /**
639 * Prints a character and then terminates the line. This method behaves as
640 * though it invokes <code>{@link #print(char)}</code> and then <code>{@link
641 * #println()}</code>.
642 *
643 * @param x the <code>char</code> value to be printed
644 */
645 public void println(char x) {
646 synchronized (lock) {
647 print(x);
648 println();
649 }
650 }
651
652 /**
653 * Prints an integer and then terminates the line. This method behaves as
654 * though it invokes <code>{@link #print(int)}</code> and then <code>{@link
655 * #println()}</code>.
656 *
657 * @param x the <code>int</code> value to be printed
658 */
659 public void println(int x) {
660 synchronized (lock) {
661 print(x);
662 println();
663 }
664 }
665
666 /**
667 * Prints a long integer and then terminates the line. This method behaves
668 * as though it invokes <code>{@link #print(long)}</code> and then
669 * <code>{@link #println()}</code>.
670 *
671 * @param x the <code>long</code> value to be printed
672 */
673 public void println(long x) {
674 synchronized (lock) {
675 print(x);
676 println();
677 }
678 }
679
680 /**
681 * Prints a floating-point number and then terminates the line. This method
682 * behaves as though it invokes <code>{@link #print(float)}</code> and then
683 * <code>{@link #println()}</code>.
684 *
685 * @param x the <code>float</code> value to be printed
686 */
687 public void println(float x) {
688 synchronized (lock) {
689 print(x);
690 println();
691 }
692 }
693
694 /**
695 * Prints a double-precision floating-point number and then terminates the
696 * line. This method behaves as though it invokes <code>{@link
697 * #print(double)}</code> and then <code>{@link #println()}</code>.
698 *
699 * @param x the <code>double</code> value to be printed
700 */
701 public void println(double x) {
702 synchronized (lock) {
703 print(x);
704 println();
705 }
706 }
707
708 /**
709 * Prints an array of characters and then terminates the line. This method
710 * behaves as though it invokes <code>{@link #print(char[])}</code> and then
711 * <code>{@link #println()}</code>.
712 *
713 * @param x the array of <code>char</code> values to be printed
714 */
715 public void println(char x[]) {
716 synchronized (lock) {
717 print(x);
718 println();
719 }
720 }
721
722 /**
723 * Prints a String and then terminates the line. This method behaves as
724 * though it invokes <code>{@link #print(String)}</code> and then
725 * <code>{@link #println()}</code>.
726 *
727 * @param x the <code>String</code> value to be printed
728 */
729 public void println(String x) {
730 synchronized (lock) {
731 print(x);
732 println();
733 }
734 }
735
736 /**
737 * Prints an Object and then terminates the line. This method calls
738 * at first String.valueOf(x) to get the printed object's string value,
739 * then behaves as
740 * though it invokes <code>{@link #print(String)}</code> and then
741 * <code>{@link #println()}</code>.
742 *
743 * @param x The <code>Object</code> to be printed.
744 */
745 public void println(Object x) {
746 String s = String.valueOf(x);
747 synchronized (lock) {
748 print(s);
749 println();
750 }
751 }
752
753 /**
754 * A convenience method to write a formatted string to this writer using
755 * the specified format string and arguments. If automatic flushing is
756 * enabled, calls to this method will flush the output buffer.
757 *
758 * <p> An invocation of this method of the form <tt>out.printf(format,
759 * args)</tt> behaves in exactly the same way as the invocation
760 *
761 * <pre>
762 * out.format(format, args) </pre>
763 *
764 * @param format
765 * A format string as described in <a
766 * href="../util/Formatter.html#syntax">Format string syntax</a>.
767 *
768 * @param args
769 * Arguments referenced by the format specifiers in the format
770 * string. If there are more arguments than format specifiers, the
771 * extra arguments are ignored. The number of arguments is
772 * variable and may be zero. The maximum number of arguments is
773 * limited by the maximum dimension of a Java array as defined by
774 * <cite>The Java™ Virtual Machine Specification</cite>.
775 * The behaviour on a
776 * <tt>null</tt> argument depends on the <a
777 * href="../util/Formatter.html#syntax">conversion</a>.
778 *
779 * @throws java.util.IllegalFormatException
780 * If a format string contains an illegal syntax, a format
781 * specifier that is incompatible with the given arguments,
782 * insufficient arguments given the format string, or other
783 * illegal conditions. For specification of all possible
784 * formatting errors, see the <a
785 * href="../util/Formatter.html#detail">Details</a> section of the
786 * formatter class specification.
787 *
788 * @throws NullPointerException
789 * If the <tt>format</tt> is <tt>null</tt>
790 *
791 * @return This writer
792 *
793 * @since 1.5
794 */
795 public PrintWriter printf(String format, Object ... args) {
796 return format(format, args);
797 }
798
799 /**
800 * A convenience method to write a formatted string to this writer using
801 * the specified format string and arguments. If automatic flushing is
802 * enabled, calls to this method will flush the output buffer.
803 *
804 * <p> An invocation of this method of the form <tt>out.printf(l, format,
805 * args)</tt> behaves in exactly the same way as the invocation
806 *
807 * <pre>
808 * out.format(l, format, args) </pre>
809 *
810 * @param l
811 * The {@linkplain java.util.Locale locale} to apply during
812 * formatting. If <tt>l</tt> is <tt>null</tt> then no localization
813 * is applied.
814 *
815 * @param format
816 * A format string as described in <a
817 * href="../util/Formatter.html#syntax">Format string syntax</a>.
818 *
819 * @param args
820 * Arguments referenced by the format specifiers in the format
821 * string. If there are more arguments than format specifiers, the
822 * extra arguments are ignored. The number of arguments is
823 * variable and may be zero. The maximum number of arguments is
824 * limited by the maximum dimension of a Java array as defined by
825 * <cite>The Java™ Virtual Machine Specification</cite>.
826 * The behaviour on a
827 * <tt>null</tt> argument depends on the <a
828 * href="../util/Formatter.html#syntax">conversion</a>.
829 *
830 * @throws java.util.IllegalFormatException
831 * If a format string contains an illegal syntax, a format
832 * specifier that is incompatible with the given arguments,
833 * insufficient arguments given the format string, or other
834 * illegal conditions. For specification of all possible
835 * formatting errors, see the <a
836 * href="../util/Formatter.html#detail">Details</a> section of the
837 * formatter class specification.
838 *
839 * @throws NullPointerException
840 * If the <tt>format</tt> is <tt>null</tt>
841 *
842 * @return This writer
843 *
844 * @since 1.5
845 */
846 public PrintWriter printf(Locale l, String format, Object ... args) {
847 return format(l, format, args);
848 }
849
850 /**
851 * Writes a formatted string to this writer using the specified format
852 * string and arguments. If automatic flushing is enabled, calls to this
853 * method will flush the output buffer.
854 *
855 * <p> The locale always used is the one returned by {@link
856 * java.util.Locale#getDefault() Locale.getDefault()}, regardless of any
857 * previous invocations of other formatting methods on this object.
858 *
859 * @param format
860 * A format string as described in <a
861 * href="../util/Formatter.html#syntax">Format string syntax</a>.
862 *
863 * @param args
864 * Arguments referenced by the format specifiers in the format
865 * string. If there are more arguments than format specifiers, the
866 * extra arguments are ignored. The number of arguments is
867 * variable and may be zero. The maximum number of arguments is
868 * limited by the maximum dimension of a Java array as defined by
869 * <cite>The Java™ Virtual Machine Specification</cite>.
870 * The behaviour on a
871 * <tt>null</tt> argument depends on the <a
872 * href="../util/Formatter.html#syntax">conversion</a>.
873 *
874 * @throws java.util.IllegalFormatException
875 * If a format string contains an illegal syntax, a format
876 * specifier that is incompatible with the given arguments,
877 * insufficient arguments given the format string, or other
878 * illegal conditions. For specification of all possible
879 * formatting errors, see the <a
880 * href="../util/Formatter.html#detail">Details</a> section of the
881 * Formatter class specification.
882 *
883 * @throws NullPointerException
884 * If the <tt>format</tt> is <tt>null</tt>
885 *
886 * @return This writer
887 *
888 * @since 1.5
889 */
890 public PrintWriter format(String format, Object ... args) {
891 try {
892 synchronized (lock) {
893 ensureOpen();
894 if ((formatter == null)
895 || (formatter.locale() != Locale.getDefault()))
896 formatter = new Formatter(this);
897 formatter.format(Locale.getDefault(), format, args);
898 if (autoFlush)
899 out.flush();
900 }
901 } catch (InterruptedIOException x) {
902 Thread.currentThread().interrupt();
903 } catch (IOException x) {
904 trouble = true;
905 }
906 return this;
907 }
908
909 /**
910 * Writes a formatted string to this writer using the specified format
911 * string and arguments. If automatic flushing is enabled, calls to this
912 * method will flush the output buffer.
913 *
914 * @param l
915 * The {@linkplain java.util.Locale locale} to apply during
916 * formatting. If <tt>l</tt> is <tt>null</tt> then no localization
917 * is applied.
918 *
919 * @param format
920 * A format string as described in <a
921 * href="../util/Formatter.html#syntax">Format string syntax</a>.
922 *
923 * @param args
924 * Arguments referenced by the format specifiers in the format
925 * string. If there are more arguments than format specifiers, the
926 * extra arguments are ignored. The number of arguments is
927 * variable and may be zero. The maximum number of arguments is
928 * limited by the maximum dimension of a Java array as defined by
929 * <cite>The Java™ Virtual Machine Specification</cite>.
930 * The behaviour on a
931 * <tt>null</tt> argument depends on the <a
932 * href="../util/Formatter.html#syntax">conversion</a>.
933 *
934 * @throws java.util.IllegalFormatException
935 * If a format string contains an illegal syntax, a format
936 * specifier that is incompatible with the given arguments,
937 * insufficient arguments given the format string, or other
938 * illegal conditions. For specification of all possible
939 * formatting errors, see the <a
940 * href="../util/Formatter.html#detail">Details</a> section of the
941 * formatter class specification.
942 *
943 * @throws NullPointerException
944 * If the <tt>format</tt> is <tt>null</tt>
945 *
946 * @return This writer
947 *
948 * @since 1.5
949 */
950 public PrintWriter format(Locale l, String format, Object ... args) {
951 try {
952 synchronized (lock) {
953 ensureOpen();
954 if ((formatter == null) || (formatter.locale() != l))
955 formatter = new Formatter(this, l);
956 formatter.format(l, format, args);
957 if (autoFlush)
958 out.flush();
959 }
960 } catch (InterruptedIOException x) {
961 Thread.currentThread().interrupt();
962 } catch (IOException x) {
963 trouble = true;
964 }
965 return this;
966 }
967
968 /**
969 * Appends the specified character sequence to this writer.
970 *
971 * <p> An invocation of this method of the form <tt>out.append(csq)</tt>
972 * behaves in exactly the same way as the invocation
973 *
974 * <pre>
975 * out.write(csq.toString()) </pre>
976 *
977 * <p> Depending on the specification of <tt>toString</tt> for the
978 * character sequence <tt>csq</tt>, the entire sequence may not be
979 * appended. For instance, invoking the <tt>toString</tt> method of a
980 * character buffer will return a subsequence whose content depends upon
981 * the buffer's position and limit.
982 *
983 * @param csq
984 * The character sequence to append. If <tt>csq</tt> is
985 * <tt>null</tt>, then the four characters <tt>"null"</tt> are
986 * appended to this writer.
987 *
988 * @return This writer
989 *
990 * @since 1.5
991 */
992 public PrintWriter append(CharSequence csq) {
993 if (csq == null)
994 write("null");
995 else
996 write(csq.toString());
997 return this;
998 }
999
1000 /**
1001 * Appends a subsequence of the specified character sequence to this writer.
1002 *
1003 * <p> An invocation of this method of the form <tt>out.append(csq, start,
1004 * end)</tt> when <tt>csq</tt> is not <tt>null</tt>, behaves in
1005 * exactly the same way as the invocation
1006 *
1007 * <pre>
1008 * out.write(csq.subSequence(start, end).toString()) </pre>
1009 *
1010 * @param csq
1011 * The character sequence from which a subsequence will be
1012 * appended. If <tt>csq</tt> is <tt>null</tt>, then characters
1013 * will be appended as if <tt>csq</tt> contained the four
1014 * characters <tt>"null"</tt>.
1015 *
1016 * @param start
1017 * The index of the first character in the subsequence
1018 *
1019 * @param end
1020 * The index of the character following the last character in the
1021 * subsequence
1022 *
1023 * @return This writer
1024 *
1025 * @throws IndexOutOfBoundsException
1026 * If <tt>start</tt> or <tt>end</tt> are negative, <tt>start</tt>
1027 * is greater than <tt>end</tt>, or <tt>end</tt> is greater than
1028 * <tt>csq.length()</tt>
1029 *
1030 * @since 1.5
1031 */
1032 public PrintWriter append(CharSequence csq, int start, int end) {
1033 CharSequence cs = (csq == null ? "null" : csq);
1034 write(cs.subSequence(start, end).toString());
1035 return this;
1036 }
1037
1038 /**
1039 * Appends the specified character to this writer.
1040 *
1041 * <p> An invocation of this method of the form <tt>out.append(c)</tt>
1042 * behaves in exactly the same way as the invocation
1043 *
1044 * <pre>
1045 * out.write(c) </pre>
1046 *
1047 * @param c
1048 * The 16-bit character to append
1049 *
1050 * @return This writer
1051 *
1052 * @since 1.5
1053 */
1054 public PrintWriter append(char c) {
1055 write(c);
1056 return this;
1057 }
1058 }