001    /* PrintWriter.java -- prints primitive values and objects to a stream as text
002       Copyright (C) 1998, 1999, 2000, 2001, 2005  Free Software Foundation
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010     
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    package java.io;
039    
040    import java.util.Locale;
041    import java.util.Formatter;
042    
043    /* Written using "Java Class Libraries", 2nd edition, plus online
044     * API docs for JDK 1.2 beta from http://www.javasoft.com.
045     * Status:  Believed complete and correct.
046     * However, should use native methods for conversion.
047     */
048    
049    /**
050     * This class prints Java primitive values and objects to a stream as
051     * text.  None of the methods in this class throw an exception.  However,
052     * errors can be detected by calling the <code>checkError()</code> method.
053     * Additionally, this stream can be designated as "autoflush" when 
054     * created so that any writes are automatically flushed to the underlying
055     * output sink whenever one of the <code>println</code> methods is
056     * called.  (Note that this differs from the <code>PrintStream</code>
057     * class which also auto-flushes when it encounters a newline character
058     * in the chars written).
059     *
060     * @author Per Bothner (bothner@cygnus.com)
061     * @author Aaron M. Renn (arenn@urbanophile.com)
062     * @date April 17, 1998.  
063     */
064    public class PrintWriter extends Writer
065    {
066      /**
067       * <code>true</code> if auto-flush is enabled, <code>false</code> otherwise
068       */
069      private boolean autoflush;
070    
071      /**
072       * This boolean indicates whether or not an error has ever occurred
073       * on this stream.
074       */
075      private boolean error;
076      
077      /**
078       * Indicates whether or not the stream has been closed.
079       */
080      private boolean closed;
081    
082      /**
083       * This is the underlying <code>Writer</code> we are sending output
084       * to
085       */
086      protected Writer out;
087    
088      /**
089       * This method intializes a new <code>PrintWriter</code> object to write
090       * to the specified output sink.  The form of the constructor does not
091       * enable auto-flush functionality.
092       *
093       * @param wr The <code>Writer</code> to write to.
094       */
095      public PrintWriter(Writer wr)
096      {
097        super(wr.lock);
098        this.out = wr;
099      }
100    
101      /**
102       * This method intializes a new <code>PrintWriter</code> object to write
103       * to the specified output sink.  This constructor also allows "auto-flush"
104       * functionality to be specified where the stream will be flushed after
105       * every line is terminated or newline character is written.
106       *
107       * @param wr The <code>Writer</code> to write to.
108       * @param autoflush <code>true</code> to flush the stream after every 
109       * line, <code>false</code> otherwise
110       */
111      public PrintWriter(Writer wr, boolean autoflush)
112      {
113        super(wr.lock);
114        this.out = wr;
115        this.autoflush = autoflush;
116      }
117    
118      /**
119       * This method initializes a new <code>PrintWriter</code> object to write
120       * to the specified <code>OutputStream</code>.  Characters will be converted
121       * to chars using the system default encoding.  Auto-flush functionality
122       * will not be enabled.
123       *
124       * @param out The <code>OutputStream</code> to write to
125       */
126      public PrintWriter(OutputStream out)
127      {
128        super();
129        this.out = new OutputStreamWriter(out);
130        this.lock = this.out;
131      }
132    
133      /**
134       * This method initializes a new <code>PrintWriter</code> object to write
135       * to the specified <code>OutputStream</code>.  Characters will be converted
136       * to chars using the system default encoding.  This form of the 
137       * constructor allows auto-flush functionality to be enabled if desired
138       *
139       * @param out The <code>OutputStream</code> to write to
140       * @param autoflush <code>true</code> to flush the stream after every 
141       * <code>println</code> call, <code>false</code> otherwise.
142       */
143      public PrintWriter(OutputStream out, boolean autoflush)
144      {
145        this(out);
146        this.autoflush = autoflush;
147      }
148    
149      /**
150       * This initializes a new PrintWriter object to write to the specified
151       * file.  It creates a FileOutputStream object and wraps it in an
152       * OutputStreamWriter using the default encoding.
153       * @param file name of the file to write to
154       * @throws FileNotFoundException if the file cannot be written or created
155       * 
156       * @since 1.5
157       */
158      public PrintWriter(String file) throws FileNotFoundException
159      {
160        this(new FileOutputStream(file));
161      }
162    
163      /**
164       * This initializes a new PrintWriter object to write to the specified
165       * file.  It creates a FileOutputStream object and wraps it in an
166       * OutputStreamWriter using the specified encoding.
167       * @param file name of the file to write to
168       * @param enc the encoding to use
169       * @throws FileNotFoundException if the file cannot be written or created
170       * @throws UnsupportedEncodingException if the encoding is not supported
171       * 
172       * @since 1.5
173       */
174      public PrintWriter(String file, String enc) 
175        throws FileNotFoundException, UnsupportedEncodingException
176      {
177        this(new OutputStreamWriter(new FileOutputStream(file), enc));
178      }
179    
180      /**
181       * This initializes a new PrintWriter object to write to the specified
182       * file.  It creates a FileOutputStream object and wraps it in an
183       * OutputStreamWriter using the default encoding.
184       * @param file the file to write to
185       * @throws FileNotFoundException if the file cannot be written or created
186       * 
187       * @since 1.5
188       */
189      public PrintWriter(File file) throws FileNotFoundException
190      {
191        this(new FileOutputStream(file));
192      }
193    
194      /**
195       * This initializes a new PrintWriter object to write to the specified
196       * file.  It creates a FileOutputStream object and wraps it in an
197       * OutputStreamWriter using the specified encoding.
198       * @param file the file to write to
199       * @param enc the encoding to use
200       * @throws FileNotFoundException if the file cannot be written or created
201       * @throws UnsupportedEncodingException if the encoding is not supported
202       * 
203       * @since 1.5
204       */
205      public PrintWriter(File file, String enc) 
206        throws FileNotFoundException, UnsupportedEncodingException
207      {
208        this(new OutputStreamWriter(new FileOutputStream(file), enc));
209      }
210    
211      /**
212       * This method can be called by subclasses to indicate that an error
213       * has occurred and should be reported by <code>checkError</code>.
214       */
215      protected void setError()
216      {
217        error = true;
218      }
219    
220      /**
221       * This method checks to see if an error has occurred on this stream.  Note
222       * that once an error has occurred, this method will continue to report
223       * <code>true</code> forever for this stream.  Before checking for an
224       * error condition, this method flushes the stream.
225       *
226       * @return <code>true</code> if an error has occurred, 
227       * <code>false</code> otherwise
228       */
229      public boolean checkError()
230      {
231        if (! closed)
232          flush();
233        return error;
234      }
235    
236      /**
237       * This method flushes any buffered chars to the underlying stream and
238       * then flushes that stream as well.
239       */
240      public void flush()
241      {
242        try
243          {
244            out.flush();
245          }
246        catch (IOException ex)
247          {
248            error = true;
249          }
250      }
251    
252      /**
253       * This method closes this stream and all underlying streams.
254       */
255      public void close()
256      {
257        try
258          {
259            out.close();
260            closed = true;
261          }
262        catch (IOException ex)
263          {
264            error = true;
265          }
266      }
267    
268      /**
269       * This method prints a <code>String</code> to the stream.  The actual
270       * value printed depends on the system default encoding.
271       *
272       * @param str The <code>String</code> to print.
273       */
274      public void print(String str)
275      {
276        write(str == null ? "null" : str);
277      }
278    
279      /**
280       * This method prints a char to the stream.  The actual value printed is
281       * determined by the character encoding in use.
282       *
283       * @param ch The <code>char</code> value to be printed
284       */
285      public void print(char ch)
286      {
287        write((int) ch);
288      }
289    
290      /**
291       * This method prints an array of characters to the stream.  The actual
292       * value printed depends on the system default encoding.
293       *
294       * @param charArray The array of characters to print.
295       */
296      public void print(char[] charArray)
297      {
298        write(charArray, 0, charArray.length);
299      }
300    
301      /**
302       * This methods prints a boolean value to the stream.  <code>true</code>
303       * values are printed as "true" and <code>false</code> values are printed
304       * as "false".
305       *
306       * @param bool The <code>boolean</code> value to print
307       */
308      public void print(boolean bool)
309      {
310        // We purposely call write() and not print() here.  This preserves
311        // compatibility with JDK 1.2.
312        write (bool ? "true" : "false");
313      }
314    
315      /**
316       * This method prints an integer to the stream.  The value printed is
317       * determined using the <code>String.valueOf()</code> method.
318       *
319       * @param inum The <code>int</code> value to be printed
320       */
321      public void print(int inum)
322      {
323        // We purposely call write() and not print() here.  This preserves
324        // compatibility with JDK 1.2.
325        write(Integer.toString(inum));
326      }
327    
328      /**
329       * This method prints a long to the stream.  The value printed is
330       * determined using the <code>String.valueOf()</code> method.
331       *
332       * @param lnum The <code>long</code> value to be printed
333       */
334      public void print(long lnum)
335      {
336        // We purposely call write() and not print() here.  This preserves
337        // compatibility with JDK 1.2.
338        write(Long.toString(lnum));
339      }
340    
341      /**
342       * This method prints a float to the stream.  The value printed is
343       * determined using the <code>String.valueOf()</code> method.
344       *
345       * @param fnum The <code>float</code> value to be printed
346       */
347      public void print(float fnum)
348      {
349        // We purposely call write() and not print() here.  This preserves
350        // compatibility with JDK 1.2.
351        write(Float.toString(fnum));
352      }
353    
354      /**
355       * This method prints a double to the stream.  The value printed is
356       * determined using the <code>String.valueOf()</code> method.
357       *
358       * @param dnum The <code>double</code> value to be printed
359       */
360      public void print(double dnum)
361      {
362        // We purposely call write() and not print() here.  This preserves
363        // compatibility with JDK 1.2.
364        write(Double.toString(dnum));
365      }
366    
367      /**
368       * This method prints an <code>Object</code> to the stream.  The actual
369       * value printed is determined by calling the <code>String.valueOf()</code>
370       * method.
371       *
372       * @param obj The <code>Object</code> to print.
373       */
374      public void print(Object obj)
375      {
376        // We purposely call write() and not print() here.  This preserves
377        // compatibility with JDK 1.2.
378        write(obj == null ? "null" : obj.toString());
379      }
380    
381      /**
382       * This is the system dependent line separator
383       */
384      private static final char[] line_separator
385        = System.getProperty("line.separator", "\n").toCharArray(); 
386    
387      /**
388       * This method prints a line separator sequence to the stream.  The value
389       * printed is determined by the system property <xmp>line.separator</xmp>
390       * and is not necessarily the Unix '\n' newline character.
391       */
392      public void println()
393      {
394        synchronized (lock)
395          {
396            try
397              {
398                write(line_separator, 0, line_separator.length);
399                if (autoflush)
400                  out.flush();
401              }
402            catch (IOException ex)
403              {
404                error = true;
405              }
406          }
407      }
408    
409      /**
410       * This methods prints a boolean value to the stream.  <code>true</code>
411       * values are printed as "true" and <code>false</code> values are printed
412       * as "false".
413       *
414       * This method prints a line termination sequence after printing the value.
415       *
416       * @param bool The <code>boolean</code> value to print
417       */
418      public void println(boolean bool)
419      {
420        synchronized (lock)
421          {
422            print(bool);
423            println();
424          }
425      }
426    
427      /**
428       * This method prints an integer to the stream.  The value printed is
429       * determined using the <code>String.valueOf()</code> method.
430       *
431       * This method prints a line termination sequence after printing the value.
432       *
433       * @param inum The <code>int</code> value to be printed
434       */
435      public void println(int inum)
436      {
437        synchronized (lock)
438          {
439            print(inum);
440            println();
441          }
442      }
443    
444      /**
445       * This method prints a long to the stream.  The value printed is
446       * determined using the <code>String.valueOf()</code> method.
447       *
448       * This method prints a line termination sequence after printing the value.
449       *
450       * @param lnum The <code>long</code> value to be printed
451       */
452      public void println(long lnum)
453      {
454        synchronized (lock)
455          {
456            print(lnum);
457            println();
458          }
459      }
460    
461      /**
462       * This method prints a float to the stream.  The value printed is
463       * determined using the <code>String.valueOf()</code> method.
464       *
465       * This method prints a line termination sequence after printing the value.
466       *
467       * @param fnum The <code>float</code> value to be printed
468       */
469      public void println(float fnum)
470      {
471        synchronized (lock)
472          {
473            print(fnum);
474            println();
475          }
476      }
477    
478      /**
479       * This method prints a double to the stream.  The value printed is
480       * determined using the <code>String.valueOf()</code> method.
481       *
482       * This method prints a line termination sequence after printing the value.
483       *
484       * @param dnum The <code>double</code> value to be printed
485       */
486      public void println(double dnum)
487      {
488        synchronized (lock)
489          {
490            print(dnum);
491            println();
492          }
493      }
494    
495      /**
496       * This method prints an <code>Object</code> to the stream.  The actual
497       * value printed is determined by calling the <code>String.valueOf()</code>
498       * method.
499       *
500       * This method prints a line termination sequence after printing the value.
501       *
502       * @param obj The <code>Object</code> to print.
503       */
504      public void println(Object obj)
505      {
506        synchronized (lock)
507          {
508            print(obj);
509            println();
510          }
511      }
512    
513      /**
514       * This method prints a <code>String</code> to the stream.  The actual
515       * value printed depends on the system default encoding.
516       *
517       * This method prints a line termination sequence after printing the value.
518       *
519       * @param str The <code>String</code> to print.
520       */
521      public void println(String str)
522      {
523        synchronized (lock)
524          {
525            print(str);
526            println();
527          }
528      }
529    
530      /**
531       * This method prints a char to the stream.  The actual value printed is
532       * determined by the character encoding in use.
533       *
534       * This method prints a line termination sequence after printing the value.
535       *
536       * @param ch The <code>char</code> value to be printed
537       */
538      public void println(char ch)
539      {
540        synchronized (lock)
541          {
542            print(ch);
543            println();
544          }
545      }
546    
547      /**
548       * This method prints an array of characters to the stream.  The actual
549       * value printed depends on the system default encoding.
550       *
551       * This method prints a line termination sequence after printing the value.
552       *
553       * @param charArray The array of characters to print.
554       */
555      public void println(char[] charArray)
556      {
557        synchronized (lock)
558          {
559            print(charArray);
560            println();
561          }
562      }
563    
564      /**
565       * This method writes a single char to the stream. 
566       * 
567       * @param ch The char to be written, passed as a int
568       */
569      public void write(int ch)
570      {
571        try
572          {
573            out.write(ch);
574          }
575        catch (IOException ex)
576          {
577            error = true;
578          }
579      }
580    
581      /**
582       * This method writes <code>count</code> chars from the specified array 
583       * starting at index <code>offset</code> into the array.
584       *
585       * @param charArray The array of chars to write
586       * @param offset The index into the array to start writing from
587       * @param count The number of chars to write
588      */
589      public void write(char[] charArray, int offset, int count)
590      {
591        try
592          {
593            out.write(charArray, offset, count);
594          }
595        catch (IOException ex)
596          {
597            error = true;
598          }
599      }
600    
601      /**
602       * This method writes <code>count</code> chars from the specified
603       * <code>String</code> to the output starting at character position
604       * <code>offset</code> into the <code>String</code>
605       *
606       * @param str The <code>String</code> to write chars from
607       * @param offset The offset into the <code>String</code> to start writing from
608       * @param count The number of chars to write.
609       */
610      public void write(String str, int offset, int count)
611      {
612        try
613          {
614            out.write(str, offset, count);
615          }
616        catch (IOException ex)
617          {
618            error = true;
619          }
620      }
621    
622      /**
623       * This method write all the chars in the specified array to the output.
624       *
625       * @param charArray The array of characters to write
626       */
627      public void write(char[] charArray)
628      {
629        write(charArray, 0, charArray.length);
630      }  
631    
632      /**
633       * This method writes the contents of the specified <code>String</code>
634       * to the underlying stream.
635       *
636       * @param str The <code>String</code> to write
637       */
638      public void write(String str)
639      {
640        write(str, 0, str.length());
641      }  
642    
643      /** @since 1.5 */
644      public PrintWriter append(char c)
645      {
646        write(c);
647        return this;
648      }
649    
650      /** @since 1.5 */
651      public PrintWriter append(CharSequence cs)
652      {
653        write(cs == null ? "null" : cs.toString());
654        return this;
655      }
656    
657      /** @since 1.5 */
658      public PrintWriter append(CharSequence cs, int start, int end)
659      {
660        write(cs == null ? "null" : cs.subSequence(start, end).toString());
661        return this;
662      }
663    
664      /** @since 1.5 */
665      public PrintWriter printf(String format, Object... args)
666      {
667        return format(format, args);
668      }
669    
670      /** @since 1.5 */
671      public PrintWriter printf(Locale locale, String format, Object... args)
672      {
673        return format(locale, format, args);
674      }
675    
676      /** @since 1.5 */
677      public PrintWriter format(String format, Object... args)
678      {
679        return format(Locale.getDefault(), format, args);
680      }
681    
682      /** @since 1.5 */
683      public PrintWriter format(Locale locale, String format, Object... args)
684      {
685        Formatter f = new Formatter(this, locale);
686        f.format(format, args);
687        return this;
688      }
689    }
690