1 /*
2 * Copyright (c) 1996, 2013, 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.Formatter;
29 import java.util.Locale;
30 import java.nio.charset.Charset;
31 import java.nio.charset.IllegalCharsetNameException;
32 import java.nio.charset.UnsupportedCharsetException;
33
34 /**
35 * A <code>PrintStream</code> adds functionality to another output stream,
36 * namely the ability to print representations of various data values
37 * conveniently. Two other features are provided as well. Unlike other output
38 * streams, a <code>PrintStream</code> never throws an
39 * <code>IOException</code>; instead, exceptional situations merely set an
40 * internal flag that can be tested via the <code>checkError</code> method.
41 * Optionally, a <code>PrintStream</code> can be created so as to flush
42 * automatically; this means that the <code>flush</code> method is
43 * automatically invoked after a byte array is written, one of the
44 * <code>println</code> methods is invoked, or a newline character or byte
45 * (<code>'\n'</code>) is written.
46 *
47 * <p> All characters printed by a <code>PrintStream</code> are converted into
48 * bytes using the platform's default character encoding. The <code>{@link
49 * PrintWriter}</code> class should be used in situations that require writing
50 * characters rather than bytes.
51 *
52 * @author Frank Yellin
53 * @author Mark Reinhold
54 * @since 1.0
55 */
56
57 public class PrintStream extends FilterOutputStream
58 implements Appendable, Closeable
59 {
60
61 private final boolean autoFlush;
62 private boolean trouble = false;
63 private Formatter formatter;
64
65 /**
66 * Track both the text- and character-output streams, so that their buffers
67 * can be flushed without flushing the entire stream.
68 */
69 private BufferedWriter textOut;
70 private OutputStreamWriter charOut;
71
72 /**
73 * requireNonNull is explicitly declared here so as not to create an extra
74 * dependency on java.util.Objects.requireNonNull. PrintStream is loaded
75 * early during system initialization.
76 */
77 private static <T> T requireNonNull(T obj, String message) {
78 if (obj == null)
79 throw new NullPointerException(message);
80 return obj;
81 }
82
83 /**
84 * Returns a charset object for the given charset name.
85 * @throws NullPointerException is csn is null
86 * @throws UnsupportedEncodingException if the charset is not supported
87 */
88 private static Charset toCharset(String csn)
89 throws UnsupportedEncodingException
90 {
91 requireNonNull(csn, "charsetName");
92 try {
93 return Charset.forName(csn);
94 } catch (IllegalCharsetNameException|UnsupportedCharsetException unused) {
95 // UnsupportedEncodingException should be thrown
96 throw new UnsupportedEncodingException(csn);
97 }
98 }
99
100 /* Private constructors */
101 private PrintStream(boolean autoFlush, OutputStream out) {
102 super(out);
103 this.autoFlush = autoFlush;
104 this.charOut = new OutputStreamWriter(this);
105 this.textOut = new BufferedWriter(charOut);
106 }
107
108 private PrintStream(boolean autoFlush, OutputStream out, Charset charset) {
109 super(out);
110 this.autoFlush = autoFlush;
111 this.charOut = new OutputStreamWriter(this, charset);
112 this.textOut = new BufferedWriter(charOut);
113 }
114
115 /* Variant of the private constructor so that the given charset name
116 * can be verified before evaluating the OutputStream argument. Used
117 * by constructors creating a FileOutputStream that also take a
118 * charset name.
119 */
120 private PrintStream(boolean autoFlush, Charset charset, OutputStream out)
121 throws UnsupportedEncodingException
122 {
123 this(autoFlush, out, charset);
124 }
125
126 /**
127 * Creates a new print stream. This stream will not flush automatically.
128 *
129 * @param out The output stream to which values and objects will be
130 * printed
131 *
132 * @see java.io.PrintWriter#PrintWriter(java.io.OutputStream)
133 */
134 public PrintStream(OutputStream out) {
135 this(out, false);
136 }
137
138 /**
139 * Creates a new print stream.
140 *
141 * @param out The output stream to which values and objects will be
142 * printed
143 * @param autoFlush A boolean; if true, the output buffer will be flushed
144 * whenever a byte array is written, one of the
145 * <code>println</code> methods is invoked, or a newline
146 * character or byte (<code>'\n'</code>) is written
147 *
148 * @see java.io.PrintWriter#PrintWriter(java.io.OutputStream, boolean)
149 */
150 public PrintStream(OutputStream out, boolean autoFlush) {
151 this(autoFlush, requireNonNull(out, "Null output stream"));
152 }
153
154 /**
155 * Creates a new print stream.
156 *
157 * @param out The output stream to which values and objects will be
158 * printed
159 * @param autoFlush A boolean; if true, the output buffer will be flushed
160 * whenever a byte array is written, one of the
161 * <code>println</code> methods is invoked, or a newline
162 * character or byte (<code>'\n'</code>) is written
163 * @param encoding The name of a supported
164 * <a href="../lang/package-summary.html#charenc">
165 * character encoding</a>
166 *
167 * @throws UnsupportedEncodingException
168 * If the named encoding is not supported
169 *
170 * @since 1.4
171 */
172 public PrintStream(OutputStream out, boolean autoFlush, String encoding)
173 throws UnsupportedEncodingException
174 {
175 this(autoFlush,
176 requireNonNull(out, "Null output stream"),
177 toCharset(encoding));
178 }
179
180 /**
181 * Creates a new print stream, without automatic line flushing, with the
182 * specified file name. This convenience constructor creates
183 * the necessary intermediate {@link java.io.OutputStreamWriter
184 * OutputStreamWriter}, which will encode characters using the
185 * {@linkplain java.nio.charset.Charset#defaultCharset() default charset}
186 * for this instance of the Java virtual machine.
187 *
188 * @param fileName
189 * The name of the file to use as the destination of this print
190 * stream. If the file exists, then it will be truncated to
191 * zero size; otherwise, a new file will be created. The output
192 * will be written to the file and is buffered.
193 *
194 * @throws FileNotFoundException
195 * If the given file object does not denote an existing, writable
196 * regular file and a new regular file of that name cannot be
197 * created, or if some other error occurs while opening or
198 * creating the file
199 *
200 * @throws SecurityException
201 * If a security manager is present and {@link
202 * SecurityManager#checkWrite checkWrite(fileName)} denies write
203 * access to the file
204 *
205 * @since 1.5
206 */
207 public PrintStream(String fileName) throws FileNotFoundException {
208 this(false, new FileOutputStream(fileName));
209 }
210
211 /**
212 * Creates a new print stream, without automatic line flushing, with the
213 * specified file name and charset. This convenience constructor creates
214 * the necessary intermediate {@link java.io.OutputStreamWriter
215 * OutputStreamWriter}, which will encode characters using the provided
216 * charset.
217 *
218 * @param fileName
219 * The name of the file to use as the destination of this print
220 * stream. If the file exists, then it will be truncated to
221 * zero size; otherwise, a new file will be created. The output
222 * will be written to the file and is buffered.
223 *
224 * @param csn
225 * The name of a supported {@linkplain java.nio.charset.Charset
226 * charset}
227 *
228 * @throws FileNotFoundException
229 * If the given file object does not denote an existing, writable
230 * regular file and a new regular file of that name cannot be
231 * created, or if some other error occurs while opening or
232 * creating the file
233 *
234 * @throws SecurityException
235 * If a security manager is present and {@link
236 * SecurityManager#checkWrite checkWrite(fileName)} denies write
237 * access to the file
238 *
239 * @throws UnsupportedEncodingException
240 * If the named charset is not supported
241 *
242 * @since 1.5
243 */
244 public PrintStream(String fileName, String csn)
245 throws FileNotFoundException, UnsupportedEncodingException
246 {
247 // ensure charset is checked before the file is opened
248 this(false, toCharset(csn), new FileOutputStream(fileName));
249 }
250
251 /**
252 * Creates a new print stream, without automatic line flushing, with the
253 * specified file. This convenience constructor creates the necessary
254 * intermediate {@link java.io.OutputStreamWriter OutputStreamWriter},
255 * which will encode characters using the {@linkplain
256 * java.nio.charset.Charset#defaultCharset() default charset} for this
257 * instance of the Java virtual machine.
258 *
259 * @param file
260 * The file to use as the destination of this print stream. If the
261 * file exists, then it will be truncated to zero size; otherwise,
262 * a new file will be created. The output will be written to the
263 * file and is buffered.
264 *
265 * @throws FileNotFoundException
266 * If the given file object does not denote an existing, writable
267 * regular file and a new regular file of that name cannot be
268 * created, or if some other error occurs while opening or
269 * creating the file
270 *
271 * @throws SecurityException
272 * If a security manager is present and {@link
273 * SecurityManager#checkWrite checkWrite(file.getPath())}
274 * denies write access to the file
275 *
276 * @since 1.5
277 */
278 public PrintStream(File file) throws FileNotFoundException {
279 this(false, new FileOutputStream(file));
280 }
281
282 /**
283 * Creates a new print stream, without automatic line flushing, with the
284 * specified file and charset. This convenience constructor creates
285 * the necessary intermediate {@link java.io.OutputStreamWriter
286 * OutputStreamWriter}, which will encode characters using the provided
287 * charset.
288 *
289 * @param file
290 * The file to use as the destination of this print stream. If the
291 * file exists, then it will be truncated to zero size; otherwise,
292 * a new file will be created. The output will be written to the
293 * file and is buffered.
294 *
295 * @param csn
296 * The name of a supported {@linkplain java.nio.charset.Charset
297 * charset}
298 *
299 * @throws FileNotFoundException
300 * If the given file object does not denote an existing, writable
301 * regular file and a new regular file of that name cannot be
302 * created, or if some other error occurs while opening or
303 * creating the file
304 *
305 * @throws SecurityException
306 * If a security manager is present and {@link
307 * SecurityManager#checkWrite checkWrite(file.getPath())}
308 * denies write access to the file
309 *
310 * @throws UnsupportedEncodingException
311 * If the named charset is not supported
312 *
313 * @since 1.5
314 */
315 public PrintStream(File file, String csn)
316 throws FileNotFoundException, UnsupportedEncodingException
317 {
318 // ensure charset is checked before the file is opened
319 this(false, toCharset(csn), new FileOutputStream(file));
320 }
321
322 /** Check to make sure that the stream has not been closed */
323 private void ensureOpen() throws IOException {
324 if (out == null)
325 throw new IOException("Stream closed");
326 }
327
328 /**
329 * Flushes the stream. This is done by writing any buffered output bytes to
330 * the underlying output stream and then flushing that stream.
331 *
332 * @see java.io.OutputStream#flush()
333 */
334 public void flush() {
335 synchronized (this) {
336 try {
337 ensureOpen();
338 out.flush();
339 }
340 catch (IOException x) {
341 trouble = true;
342 }
343 }
344 }
345
346 private boolean closing = false; /* To avoid recursive closing */
347
348 /**
349 * Closes the stream. This is done by flushing the stream and then closing
350 * the underlying output stream.
351 *
352 * @see java.io.OutputStream#close()
353 */
354 public void close() {
355 synchronized (this) {
356 if (! closing) {
357 closing = true;
358 try {
359 textOut.close();
360 out.close();
361 }
362 catch (IOException x) {
363 trouble = true;
364 }
365 textOut = null;
366 charOut = null;
367 out = null;
368 }
369 }
370 }
371
372 /**
373 * Flushes the stream and checks its error state. The internal error state
374 * is set to <code>true</code> when the underlying output stream throws an
375 * <code>IOException</code> other than <code>InterruptedIOException</code>,
376 * and when the <code>setError</code> method is invoked. If an operation
377 * on the underlying output stream throws an
378 * <code>InterruptedIOException</code>, then the <code>PrintStream</code>
379 * converts the exception back into an interrupt by doing:
380 * <pre>
381 * Thread.currentThread().interrupt();
382 * </pre>
383 * or the equivalent.
384 *
385 * @return <code>true</code> if and only if this stream has encountered an
386 * <code>IOException</code> other than
387 * <code>InterruptedIOException</code>, or the
388 * <code>setError</code> method has been invoked
389 */
390 public boolean checkError() {
391 if (out != null)
392 flush();
393 if (out instanceof java.io.PrintStream) {
394 PrintStream ps = (PrintStream) out;
395 return ps.checkError();
396 }
397 return trouble;
398 }
399
400 /**
401 * Sets the error state of the stream to <code>true</code>.
402 *
403 * <p> This method will cause subsequent invocations of {@link
404 * #checkError()} to return <tt>true</tt> until {@link
405 * #clearError()} is invoked.
406 *
407 * @since 1.1
408 */
409 protected void setError() {
410 trouble = true;
411 }
412
413 /**
414 * Clears the internal error state of this stream.
415 *
416 * <p> This method will cause subsequent invocations of {@link
417 * #checkError()} to return <tt>false</tt> until another write
418 * operation fails and invokes {@link #setError()}.
419 *
420 * @since 1.6
421 */
422 protected void clearError() {
423 trouble = false;
424 }
425
426 /*
427 * Exception-catching, synchronized output operations,
428 * which also implement the write() methods of OutputStream
429 */
430
431 /**
432 * Writes the specified byte to this stream. If the byte is a newline and
433 * automatic flushing is enabled then the <code>flush</code> method will be
434 * invoked.
435 *
436 * <p> Note that the byte is written as given; to write a character that
437 * will be translated according to the platform's default character
438 * encoding, use the <code>print(char)</code> or <code>println(char)</code>
439 * methods.
440 *
441 * @param b The byte to be written
442 * @see #print(char)
443 * @see #println(char)
444 */
445 public void write(int b) {
446 try {
447 synchronized (this) {
448 ensureOpen();
449 out.write(b);
450 if ((b == '\n') && autoFlush)
451 out.flush();
452 }
453 }
454 catch (InterruptedIOException x) {
455 Thread.currentThread().interrupt();
456 }
457 catch (IOException x) {
458 trouble = true;
459 }
460 }
461
462 /**
463 * Writes <code>len</code> bytes from the specified byte array starting at
464 * offset <code>off</code> to this stream. If automatic flushing is
465 * enabled then the <code>flush</code> method will be invoked.
466 *
467 * <p> Note that the bytes will be written as given; to write characters
468 * that will be translated according to the platform's default character
469 * encoding, use the <code>print(char)</code> or <code>println(char)</code>
470 * methods.
471 *
472 * @param buf A byte array
473 * @param off Offset from which to start taking bytes
474 * @param len Number of bytes to write
475 */
476 public void write(byte buf[], int off, int len) {
477 try {
478 synchronized (this) {
479 ensureOpen();
480 out.write(buf, off, len);
481 if (autoFlush)
482 out.flush();
483 }
484 }
485 catch (InterruptedIOException x) {
486 Thread.currentThread().interrupt();
487 }
488 catch (IOException x) {
489 trouble = true;
490 }
491 }
492
493 /*
494 * The following private methods on the text- and character-output streams
495 * always flush the stream buffers, so that writes to the underlying byte
496 * stream occur as promptly as with the original PrintStream.
497 */
498
499 private void write(char buf[]) {
500 try {
501 synchronized (this) {
502 ensureOpen();
503 textOut.write(buf);
504 textOut.flushBuffer();
505 charOut.flushBuffer();
506 if (autoFlush) {
507 for (int i = 0; i < buf.length; i++)
508 if (buf[i] == '\n')
509 out.flush();
510 }
511 }
512 }
513 catch (InterruptedIOException x) {
514 Thread.currentThread().interrupt();
515 }
516 catch (IOException x) {
517 trouble = true;
518 }
519 }
520
521 private void write(String s) {
522 try {
523 synchronized (this) {
524 ensureOpen();
525 textOut.write(s);
526 textOut.flushBuffer();
527 charOut.flushBuffer();
528 if (autoFlush && (s.indexOf('\n') >= 0))
529 out.flush();
530 }
531 }
532 catch (InterruptedIOException x) {
533 Thread.currentThread().interrupt();
534 }
535 catch (IOException x) {
536 trouble = true;
537 }
538 }
539
540 private void newLine() {
541 try {
542 synchronized (this) {
543 ensureOpen();
544 textOut.newLine();
545 textOut.flushBuffer();
546 charOut.flushBuffer();
547 if (autoFlush)
548 out.flush();
549 }
550 }
551 catch (InterruptedIOException x) {
552 Thread.currentThread().interrupt();
553 }
554 catch (IOException x) {
555 trouble = true;
556 }
557 }
558
559 /* Methods that do not terminate lines */
560
561 /**
562 * Prints a boolean value. The string produced by <code>{@link
563 * java.lang.String#valueOf(boolean)}</code> is translated into bytes
564 * according to the platform's default character encoding, and these bytes
565 * are written in exactly the manner of the
566 * <code>{@link #write(int)}</code> method.
567 *
568 * @param b The <code>boolean</code> to be printed
569 */
570 public void print(boolean b) {
571 write(b ? "true" : "false");
572 }
573
574 /**
575 * Prints a character. The character is translated into one or more bytes
576 * according to the platform's default character encoding, and these bytes
577 * are written in exactly the manner of the
578 * <code>{@link #write(int)}</code> method.
579 *
580 * @param c The <code>char</code> to be printed
581 */
582 public void print(char c) {
583 write(String.valueOf(c));
584 }
585
586 /**
587 * Prints an integer. The string produced by <code>{@link
588 * java.lang.String#valueOf(int)}</code> is translated into bytes
589 * according to the platform's default character encoding, and these bytes
590 * are written in exactly the manner of the
591 * <code>{@link #write(int)}</code> method.
592 *
593 * @param i The <code>int</code> to be printed
594 * @see java.lang.Integer#toString(int)
595 */
596 public void print(int i) {
597 write(String.valueOf(i));
598 }
599
600 /**
601 * Prints a long integer. The string produced by <code>{@link
602 * java.lang.String#valueOf(long)}</code> is translated into bytes
603 * according to the platform's default character encoding, and these bytes
604 * are written in exactly the manner of the
605 * <code>{@link #write(int)}</code> method.
606 *
607 * @param l The <code>long</code> to be printed
608 * @see java.lang.Long#toString(long)
609 */
610 public void print(long l) {
611 write(String.valueOf(l));
612 }
613
614 /**
615 * Prints a floating-point number. The string produced by <code>{@link
616 * java.lang.String#valueOf(float)}</code> is translated into bytes
617 * according to the platform's default character encoding, and these bytes
618 * are written in exactly the manner of the
619 * <code>{@link #write(int)}</code> method.
620 *
621 * @param f The <code>float</code> to be printed
622 * @see java.lang.Float#toString(float)
623 */
624 public void print(float f) {
625 write(String.valueOf(f));
626 }
627
628 /**
629 * Prints a double-precision floating-point number. The string produced by
630 * <code>{@link java.lang.String#valueOf(double)}</code> is translated into
631 * bytes according to the platform's default character encoding, and these
632 * bytes are written in exactly the manner of the <code>{@link
633 * #write(int)}</code> method.
634 *
635 * @param d The <code>double</code> to be printed
636 * @see java.lang.Double#toString(double)
637 */
638 public void print(double d) {
639 write(String.valueOf(d));
640 }
641
642 /**
643 * Prints an array of characters. The characters are converted into bytes
644 * according to the platform's default character encoding, and these bytes
645 * are written in exactly the manner of the
646 * <code>{@link #write(int)}</code> method.
647 *
648 * @param s The array of chars to be printed
649 *
650 * @throws NullPointerException If <code>s</code> is <code>null</code>
651 */
652 public void print(char s[]) {
653 write(s);
654 }
655
656 /**
657 * Prints a string. If the argument is <code>null</code> then the string
658 * <code>"null"</code> is printed. Otherwise, the string's characters are
659 * converted into bytes according to the platform's default character
660 * encoding, and these bytes are written in exactly the manner of the
661 * <code>{@link #write(int)}</code> method.
662 *
663 * @param s The <code>String</code> to be printed
664 */
665 public void print(String s) {
666 if (s == null) {
667 s = "null";
668 }
669 write(s);
670 }
671
672 /**
673 * Prints an object. The string produced by the <code>{@link
674 * java.lang.String#valueOf(Object)}</code> method is translated into bytes
675 * according to the platform's default character encoding, and these bytes
676 * are written in exactly the manner of the
677 * <code>{@link #write(int)}</code> method.
678 *
679 * @param obj The <code>Object</code> to be printed
680 * @see java.lang.Object#toString()
681 */
682 public void print(Object obj) {
683 write(String.valueOf(obj));
684 }
685
686
687 /* Methods that do terminate lines */
688
689 /**
690 * Terminates the current line by writing the line separator string. The
691 * line separator string is defined by the system property
692 * <code>line.separator</code>, and is not necessarily a single newline
693 * character (<code>'\n'</code>).
694 */
695 public void println() {
696 newLine();
697 }
698
699 /**
700 * Prints a boolean and then terminate the line. This method behaves as
701 * though it invokes <code>{@link #print(boolean)}</code> and then
702 * <code>{@link #println()}</code>.
703 *
704 * @param x The <code>boolean</code> to be printed
705 */
706 public void println(boolean x) {
707 synchronized (this) {
708 print(x);
709 newLine();
710 }
711 }
712
713 /**
714 * Prints a character and then terminate the line. This method behaves as
715 * though it invokes <code>{@link #print(char)}</code> and then
716 * <code>{@link #println()}</code>.
717 *
718 * @param x The <code>char</code> to be printed.
719 */
720 public void println(char x) {
721 synchronized (this) {
722 print(x);
723 newLine();
724 }
725 }
726
727 /**
728 * Prints an integer and then terminate the line. This method behaves as
729 * though it invokes <code>{@link #print(int)}</code> and then
730 * <code>{@link #println()}</code>.
731 *
732 * @param x The <code>int</code> to be printed.
733 */
734 public void println(int x) {
735 synchronized (this) {
736 print(x);
737 newLine();
738 }
739 }
740
741 /**
742 * Prints a long and then terminate the line. This method behaves as
743 * though it invokes <code>{@link #print(long)}</code> and then
744 * <code>{@link #println()}</code>.
745 *
746 * @param x a The <code>long</code> to be printed.
747 */
748 public void println(long x) {
749 synchronized (this) {
750 print(x);
751 newLine();
752 }
753 }
754
755 /**
756 * Prints a float and then terminate the line. This method behaves as
757 * though it invokes <code>{@link #print(float)}</code> and then
758 * <code>{@link #println()}</code>.
759 *
760 * @param x The <code>float</code> to be printed.
761 */
762 public void println(float x) {
763 synchronized (this) {
764 print(x);
765 newLine();
766 }
767 }
768
769 /**
770 * Prints a double and then terminate the line. This method behaves as
771 * though it invokes <code>{@link #print(double)}</code> and then
772 * <code>{@link #println()}</code>.
773 *
774 * @param x The <code>double</code> to be printed.
775 */
776 public void println(double x) {
777 synchronized (this) {
778 print(x);
779 newLine();
780 }
781 }
782
783 /**
784 * Prints an array of characters and then terminate the line. This method
785 * behaves as though it invokes <code>{@link #print(char[])}</code> and
786 * then <code>{@link #println()}</code>.
787 *
788 * @param x an array of chars to print.
789 */
790 public void println(char x[]) {
791 synchronized (this) {
792 print(x);
793 newLine();
794 }
795 }
796
797 /**
798 * Prints a String and then terminate the line. This method behaves as
799 * though it invokes <code>{@link #print(String)}</code> and then
800 * <code>{@link #println()}</code>.
801 *
802 * @param x The <code>String</code> to be printed.
803 */
804 public void println(String x) {
805 synchronized (this) {
806 print(x);
807 newLine();
808 }
809 }
810
811 /**
812 * Prints an Object and then terminate the line. This method calls
813 * at first String.valueOf(x) to get the printed object's string value,
814 * then behaves as
815 * though it invokes <code>{@link #print(String)}</code> and then
816 * <code>{@link #println()}</code>.
817 *
818 * @param x The <code>Object</code> to be printed.
819 */
820 public void println(Object x) {
821 String s = String.valueOf(x);
822 synchronized (this) {
823 print(s);
824 newLine();
825 }
826 }
827
828
829 /**
830 * A convenience method to write a formatted string to this output stream
831 * using the specified format string and arguments.
832 *
833 * <p> An invocation of this method of the form <tt>out.printf(format,
834 * args)</tt> behaves in exactly the same way as the invocation
835 *
836 * <pre>
837 * out.format(format, args) </pre>
838 *
839 * @param format
840 * A format string as described in <a
841 * href="../util/Formatter.html#syntax">Format string syntax</a>
842 *
843 * @param args
844 * Arguments referenced by the format specifiers in the format
845 * string. If there are more arguments than format specifiers, the
846 * extra arguments are ignored. The number of arguments is
847 * variable and may be zero. The maximum number of arguments is
848 * limited by the maximum dimension of a Java array as defined by
849 * <cite>The Java™ Virtual Machine Specification</cite>.
850 * The behaviour on a
851 * <tt>null</tt> argument depends on the <a
852 * href="../util/Formatter.html#syntax">conversion</a>.
853 *
854 * @throws java.util.IllegalFormatException
855 * If a format string contains an illegal syntax, a format
856 * specifier that is incompatible with the given arguments,
857 * insufficient arguments given the format string, or other
858 * illegal conditions. For specification of all possible
859 * formatting errors, see the <a
860 * href="../util/Formatter.html#detail">Details</a> section of the
861 * formatter class specification.
862 *
863 * @throws NullPointerException
864 * If the <tt>format</tt> is <tt>null</tt>
865 *
866 * @return This output stream
867 *
868 * @since 1.5
869 */
870 public PrintStream printf(String format, Object ... args) {
871 return format(format, args);
872 }
873
874 /**
875 * A convenience method to write a formatted string to this output stream
876 * using the specified format string and arguments.
877 *
878 * <p> An invocation of this method of the form <tt>out.printf(l, format,
879 * args)</tt> behaves in exactly the same way as the invocation
880 *
881 * <pre>
882 * out.format(l, format, args) </pre>
883 *
884 * @param l
885 * The {@linkplain java.util.Locale locale} to apply during
886 * formatting. If <tt>l</tt> is <tt>null</tt> then no localization
887 * is applied.
888 *
889 * @param format
890 * A format string as described in <a
891 * href="../util/Formatter.html#syntax">Format string syntax</a>
892 *
893 * @param args
894 * Arguments referenced by the format specifiers in the format
895 * string. If there are more arguments than format specifiers, the
896 * extra arguments are ignored. The number of arguments is
897 * variable and may be zero. The maximum number of arguments is
898 * limited by the maximum dimension of a Java array as defined by
899 * <cite>The Java™ Virtual Machine Specification</cite>.
900 * The behaviour on a
901 * <tt>null</tt> argument depends on the <a
902 * href="../util/Formatter.html#syntax">conversion</a>.
903 *
904 * @throws java.util.IllegalFormatException
905 * If a format string contains an illegal syntax, a format
906 * specifier that is incompatible with the given arguments,
907 * insufficient arguments given the format string, or other
908 * illegal conditions. For specification of all possible
909 * formatting errors, see the <a
910 * href="../util/Formatter.html#detail">Details</a> section of the
911 * formatter class specification.
912 *
913 * @throws NullPointerException
914 * If the <tt>format</tt> is <tt>null</tt>
915 *
916 * @return This output stream
917 *
918 * @since 1.5
919 */
920 public PrintStream printf(Locale l, String format, Object ... args) {
921 return format(l, format, args);
922 }
923
924 /**
925 * Writes a formatted string to this output stream using the specified
926 * format string and arguments.
927 *
928 * <p> The locale always used is the one returned by {@link
929 * java.util.Locale#getDefault() Locale.getDefault()}, regardless of any
930 * previous invocations of other formatting methods on this object.
931 *
932 * @param format
933 * A format string as described in <a
934 * href="../util/Formatter.html#syntax">Format string syntax</a>
935 *
936 * @param args
937 * Arguments referenced by the format specifiers in the format
938 * string. If there are more arguments than format specifiers, the
939 * extra arguments are ignored. The number of arguments is
940 * variable and may be zero. The maximum number of arguments is
941 * limited by the maximum dimension of a Java array as defined by
942 * <cite>The Java™ Virtual Machine Specification</cite>.
943 * The behaviour on a
944 * <tt>null</tt> argument depends on the <a
945 * href="../util/Formatter.html#syntax">conversion</a>.
946 *
947 * @throws java.util.IllegalFormatException
948 * If a format string contains an illegal syntax, a format
949 * specifier that is incompatible with the given arguments,
950 * insufficient arguments given the format string, or other
951 * illegal conditions. For specification of all possible
952 * formatting errors, see the <a
953 * href="../util/Formatter.html#detail">Details</a> section of the
954 * formatter class specification.
955 *
956 * @throws NullPointerException
957 * If the <tt>format</tt> is <tt>null</tt>
958 *
959 * @return This output stream
960 *
961 * @since 1.5
962 */
963 public PrintStream format(String format, Object ... args) {
964 try {
965 synchronized (this) {
966 ensureOpen();
967 if ((formatter == null)
968 || (formatter.locale() != Locale.getDefault()))
969 formatter = new Formatter((Appendable) this);
970 formatter.format(Locale.getDefault(), format, args);
971 }
972 } catch (InterruptedIOException x) {
973 Thread.currentThread().interrupt();
974 } catch (IOException x) {
975 trouble = true;
976 }
977 return this;
978 }
979
980 /**
981 * Writes a formatted string to this output stream using the specified
982 * format string and arguments.
983 *
984 * @param l
985 * The {@linkplain java.util.Locale locale} to apply during
986 * formatting. If <tt>l</tt> is <tt>null</tt> then no localization
987 * is applied.
988 *
989 * @param format
990 * A format string as described in <a
991 * href="../util/Formatter.html#syntax">Format string syntax</a>
992 *
993 * @param args
994 * Arguments referenced by the format specifiers in the format
995 * string. If there are more arguments than format specifiers, the
996 * extra arguments are ignored. The number of arguments is
997 * variable and may be zero. The maximum number of arguments is
998 * limited by the maximum dimension of a Java array as defined by
999 * <cite>The Java™ Virtual Machine Specification</cite>.
1000 * The behaviour on a
1001 * <tt>null</tt> argument depends on the <a
1002 * href="../util/Formatter.html#syntax">conversion</a>.
1003 *
1004 * @throws java.util.IllegalFormatException
1005 * If a format string contains an illegal syntax, a format
1006 * specifier that is incompatible with the given arguments,
1007 * insufficient arguments given the format string, or other
1008 * illegal conditions. For specification of all possible
1009 * formatting errors, see the <a
1010 * href="../util/Formatter.html#detail">Details</a> section of the
1011 * formatter class specification.
1012 *
1013 * @throws NullPointerException
1014 * If the <tt>format</tt> is <tt>null</tt>
1015 *
1016 * @return This output stream
1017 *
1018 * @since 1.5
1019 */
1020 public PrintStream format(Locale l, String format, Object ... args) {
1021 try {
1022 synchronized (this) {
1023 ensureOpen();
1024 if ((formatter == null)
1025 || (formatter.locale() != l))
1026 formatter = new Formatter(this, l);
1027 formatter.format(l, format, args);
1028 }
1029 } catch (InterruptedIOException x) {
1030 Thread.currentThread().interrupt();
1031 } catch (IOException x) {
1032 trouble = true;
1033 }
1034 return this;
1035 }
1036
1037 /**
1038 * Appends the specified character sequence to this output stream.
1039 *
1040 * <p> An invocation of this method of the form <tt>out.append(csq)</tt>
1041 * behaves in exactly the same way as the invocation
1042 *
1043 * <pre>
1044 * out.print(csq.toString()) </pre>
1045 *
1046 * <p> Depending on the specification of <tt>toString</tt> for the
1047 * character sequence <tt>csq</tt>, the entire sequence may not be
1048 * appended. For instance, invoking then <tt>toString</tt> method of a
1049 * character buffer will return a subsequence whose content depends upon
1050 * the buffer's position and limit.
1051 *
1052 * @param csq
1053 * The character sequence to append. If <tt>csq</tt> is
1054 * <tt>null</tt>, then the four characters <tt>"null"</tt> are
1055 * appended to this output stream.
1056 *
1057 * @return This output stream
1058 *
1059 * @since 1.5
1060 */
1061 public PrintStream append(CharSequence csq) {
1062 if (csq == null)
1063 print("null");
1064 else
1065 print(csq.toString());
1066 return this;
1067 }
1068
1069 /**
1070 * Appends a subsequence of the specified character sequence to this output
1071 * stream.
1072 *
1073 * <p> An invocation of this method of the form <tt>out.append(csq, start,
1074 * end)</tt> when <tt>csq</tt> is not <tt>null</tt>, behaves in
1075 * exactly the same way as the invocation
1076 *
1077 * <pre>
1078 * out.print(csq.subSequence(start, end).toString()) </pre>
1079 *
1080 * @param csq
1081 * The character sequence from which a subsequence will be
1082 * appended. If <tt>csq</tt> is <tt>null</tt>, then characters
1083 * will be appended as if <tt>csq</tt> contained the four
1084 * characters <tt>"null"</tt>.
1085 *
1086 * @param start
1087 * The index of the first character in the subsequence
1088 *
1089 * @param end
1090 * The index of the character following the last character in the
1091 * subsequence
1092 *
1093 * @return This output stream
1094 *
1095 * @throws IndexOutOfBoundsException
1096 * If <tt>start</tt> or <tt>end</tt> are negative, <tt>start</tt>
1097 * is greater than <tt>end</tt>, or <tt>end</tt> is greater than
1098 * <tt>csq.length()</tt>
1099 *
1100 * @since 1.5
1101 */
1102 public PrintStream append(CharSequence csq, int start, int end) {
1103 CharSequence cs = (csq == null ? "null" : csq);
1104 write(cs.subSequence(start, end).toString());
1105 return this;
1106 }
1107
1108 /**
1109 * Appends the specified character to this output stream.
1110 *
1111 * <p> An invocation of this method of the form <tt>out.append(c)</tt>
1112 * behaves in exactly the same way as the invocation
1113 *
1114 * <pre>
1115 * out.print(c) </pre>
1116 *
1117 * @param c
1118 * The 16-bit character to append
1119 *
1120 * @return This output stream
1121 *
1122 * @since 1.5
1123 */
1124 public PrintStream append(char c) {
1125 print(c);
1126 return this;
1127 }
1128
1129 }