Java tutorial
/* * Copyright (c) 1996, 2019, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.io; import java.util.Objects; import java.util.Formatter; import java.util.Locale; import java.nio.charset.Charset; import java.nio.charset.IllegalCharsetNameException; import java.nio.charset.UnsupportedCharsetException; /** * Prints formatted representations of objects to a text-output stream. This * class implements all of the {@code print} methods found in {@link * PrintStream}. It does not contain methods for writing raw bytes, for which * a program should use unencoded byte streams. * * <p> Unlike the {@link PrintStream} class, if automatic flushing is enabled * it will be done only when one of the {@code println}, {@code printf}, or * {@code format} methods is invoked, rather than whenever a newline character * happens to be output. These methods use the platform's own notion of line * separator rather than the newline character. * * <p> Methods in this class never throw I/O exceptions, although some of its * constructors may. The client may inquire as to whether any errors have * occurred by invoking {@link #checkError checkError()}. * * <p> This class always replaces malformed and unmappable character sequences with * the charset's default replacement string. * The {@linkplain java.nio.charset.CharsetEncoder} class should be used when more * control over the encoding process is required. * * @author Frank Yellin * @author Mark Reinhold * @since 1.1 */ public class PrintWriter extends Writer { /** * The underlying character-output stream of this * {@code PrintWriter}. * * @since 1.2 */ protected Writer out; private final boolean autoFlush; private boolean trouble = false; private Formatter formatter; private PrintStream psOut = null; /** * Returns a charset object for the given charset name. * @throws NullPointerException is csn is null * @throws UnsupportedEncodingException if the charset is not supported */ private static Charset toCharset(String csn) throws UnsupportedEncodingException { Objects.requireNonNull(csn, "charsetName"); try { return Charset.forName(csn); } catch (IllegalCharsetNameException | UnsupportedCharsetException unused) { // UnsupportedEncodingException should be thrown throw new UnsupportedEncodingException(csn); } } /** * Creates a new PrintWriter, without automatic line flushing. * * @param out A character-output stream */ public PrintWriter(Writer out) { this(out, false); } /** * Creates a new PrintWriter. * * @param out A character-output stream * @param autoFlush A boolean; if true, the {@code println}, * {@code printf}, or {@code format} methods will * flush the output buffer */ public PrintWriter(Writer out, boolean autoFlush) { super(out); this.out = out; this.autoFlush = autoFlush; } /** * Creates a new PrintWriter, without automatic line flushing, from an * existing OutputStream. This convenience constructor creates the * necessary intermediate OutputStreamWriter, which will convert characters * into bytes using the default character encoding. * * @param out An output stream * * @see java.io.OutputStreamWriter#OutputStreamWriter(java.io.OutputStream) */ public PrintWriter(OutputStream out) { this(out, false); } /** * Creates a new PrintWriter from an existing OutputStream. This * convenience constructor creates the necessary intermediate * OutputStreamWriter, which will convert characters into bytes using the * default character encoding. * * @param out An output stream * @param autoFlush A boolean; if true, the {@code println}, * {@code printf}, or {@code format} methods will * flush the output buffer * * @see java.io.OutputStreamWriter#OutputStreamWriter(java.io.OutputStream) */ public PrintWriter(OutputStream out, boolean autoFlush) { this(out, autoFlush, Charset.defaultCharset()); } /** * Creates a new PrintWriter from an existing OutputStream. This * convenience constructor creates the necessary intermediate * OutputStreamWriter, which will convert characters into bytes using the * specified charset. * * @param out An output stream * @param autoFlush A boolean; if true, the {@code println}, * {@code printf}, or {@code format} methods will * flush the output buffer * @param charset * A {@linkplain java.nio.charset.Charset charset} * * @since 10 */ public PrintWriter(OutputStream out, boolean autoFlush, Charset charset) { this(new BufferedWriter(new OutputStreamWriter(out, charset)), autoFlush); // save print stream for error propagation if (out instanceof java.io.PrintStream) { psOut = (PrintStream) out; } } /** * Creates a new PrintWriter, without automatic line flushing, with the * specified file name. This convenience constructor creates the necessary * intermediate {@link java.io.OutputStreamWriter OutputStreamWriter}, * which will encode characters using the {@linkplain * java.nio.charset.Charset#defaultCharset() default charset} for this * instance of the Java virtual machine. * * @param fileName * The name of the file to use as the destination of this writer. * If the file exists then it will be truncated to zero size; * otherwise, a new file will be created. The output will be * written to the file and is buffered. * * @throws FileNotFoundException * If the given string does not denote an existing, writable * regular file and a new regular file of that name cannot be * created, or if some other error occurs while opening or * creating the file * * @throws SecurityException * If a security manager is present and {@link * SecurityManager#checkWrite checkWrite(fileName)} denies write * access to the file * * @since 1.5 */ public PrintWriter(String fileName) throws FileNotFoundException { this(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(fileName))), false); } /* Private constructor */ private PrintWriter(Charset charset, File file) throws FileNotFoundException { this(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file), charset)), false); } /** * Creates a new PrintWriter, without automatic line flushing, with the * specified file name and charset. This convenience constructor creates * the necessary intermediate {@link java.io.OutputStreamWriter * OutputStreamWriter}, which will encode characters using the provided * charset. * * @param fileName * The name of the file to use as the destination of this writer. * If the file exists then it will be truncated to zero size; * otherwise, a new file will be created. The output will be * written to the file and is buffered. * * @param csn * The name of a supported {@linkplain java.nio.charset.Charset * charset} * * @throws FileNotFoundException * If the given string does not denote an existing, writable * regular file and a new regular file of that name cannot be * created, or if some other error occurs while opening or * creating the file * * @throws SecurityException * If a security manager is present and {@link * SecurityManager#checkWrite checkWrite(fileName)} denies write * access to the file * * @throws UnsupportedEncodingException * If the named charset is not supported * * @since 1.5 */ public PrintWriter(String fileName, String csn) throws FileNotFoundException, UnsupportedEncodingException { this(toCharset(csn), new File(fileName)); } /** * Creates a new PrintWriter, without automatic line flushing, with the * specified file name and charset. This convenience constructor creates * the necessary intermediate {@link java.io.OutputStreamWriter * OutputStreamWriter}, which will encode characters using the provided * charset. * * @param fileName * The name of the file to use as the destination of this writer. * If the file exists then it will be truncated to zero size; * otherwise, a new file will be created. The output will be * written to the file and is buffered. * * @param charset * A {@linkplain java.nio.charset.Charset charset} * * @throws IOException * if an I/O error occurs while opening or creating the file * * @throws SecurityException * If a security manager is present and {@link * SecurityManager#checkWrite checkWrite(fileName)} denies write * access to the file * * @since 10 */ public PrintWriter(String fileName, Charset charset) throws IOException { this(Objects.requireNonNull(charset, "charset"), new File(fileName)); } /** * Creates a new PrintWriter, without automatic line flushing, with the * specified file. This convenience constructor creates the necessary * intermediate {@link java.io.OutputStreamWriter OutputStreamWriter}, * which will encode characters using the {@linkplain * java.nio.charset.Charset#defaultCharset() default charset} for this * instance of the Java virtual machine. * * @param file * The file to use as the destination of this writer. If the file * exists then it will be truncated to zero size; otherwise, a new * file will be created. The output will be written to the file * and is buffered. * * @throws FileNotFoundException * If the given file object does not denote an existing, writable * regular file and a new regular file of that name cannot be * created, or if some other error occurs while opening or * creating the file * * @throws SecurityException * If a security manager is present and {@link * SecurityManager#checkWrite checkWrite(file.getPath())} * denies write access to the file * * @since 1.5 */ public PrintWriter(File file) throws FileNotFoundException { this(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file))), false); } /** * Creates a new PrintWriter, without automatic line flushing, with the * specified file and charset. This convenience constructor creates the * necessary intermediate {@link java.io.OutputStreamWriter * OutputStreamWriter}, which will encode characters using the provided * charset. * * @param file * The file to use as the destination of this writer. If the file * exists then it will be truncated to zero size; otherwise, a new * file will be created. The output will be written to the file * and is buffered. * * @param csn * The name of a supported {@linkplain java.nio.charset.Charset * charset} * * @throws FileNotFoundException * If the given file object does not denote an existing, writable * regular file and a new regular file of that name cannot be * created, or if some other error occurs while opening or * creating the file * * @throws SecurityException * If a security manager is present and {@link * SecurityManager#checkWrite checkWrite(file.getPath())} * denies write access to the file * * @throws UnsupportedEncodingException * If the named charset is not supported * * @since 1.5 */ public PrintWriter(File file, String csn) throws FileNotFoundException, UnsupportedEncodingException { this(toCharset(csn), file); } /** * Creates a new PrintWriter, without automatic line flushing, with the * specified file and charset. This convenience constructor creates the * necessary intermediate {@link java.io.OutputStreamWriter * OutputStreamWriter}, which will encode characters using the provided * charset. * * @param file * The file to use as the destination of this writer. If the file * exists then it will be truncated to zero size; otherwise, a new * file will be created. The output will be written to the file * and is buffered. * * @param charset * A {@linkplain java.nio.charset.Charset charset} * * @throws IOException * if an I/O error occurs while opening or creating the file * * @throws SecurityException * If a security manager is present and {@link * SecurityManager#checkWrite checkWrite(file.getPath())} * denies write access to the file * * @since 10 */ public PrintWriter(File file, Charset charset) throws IOException { this(Objects.requireNonNull(charset, "charset"), file); } /** Checks to make sure that the stream has not been closed */ private void ensureOpen() throws IOException { if (out == null) throw new IOException("Stream closed"); } /** * Flushes the stream. * @see #checkError() */ public void flush() { try { synchronized (lock) { ensureOpen(); out.flush(); } } catch (IOException x) { trouble = true; } } /** * Closes the stream and releases any system resources associated * with it. Closing a previously closed stream has no effect. * * @see #checkError() */ public void close() { try { synchronized (lock) { if (out == null) return; out.close(); out = null; } } catch (IOException x) { trouble = true; } } /** * Flushes the stream if it's not closed and checks its error state. * * @return {@code true} if the print stream has encountered an error, * either on the underlying output stream or during a format * conversion. */ public boolean checkError() { if (out != null) { flush(); } if (out instanceof java.io.PrintWriter) { PrintWriter pw = (PrintWriter) out; return pw.checkError(); } else if (psOut != null) { return psOut.checkError(); } return trouble; } /** * Indicates that an error has occurred. * * <p> This method will cause subsequent invocations of {@link * #checkError()} to return {@code true} until {@link * #clearError()} is invoked. */ protected void setError() { trouble = true; } /** * Clears the error state of this stream. * * <p> This method will cause subsequent invocations of {@link * #checkError()} to return {@code false} until another write * operation fails and invokes {@link #setError()}. * * @since 1.6 */ protected void clearError() { trouble = false; } /* * Exception-catching, synchronized output operations, * which also implement the write() methods of Writer */ /** * Writes a single character. * @param c int specifying a character to be written. */ public void write(int c) { try { synchronized (lock) { ensureOpen(); out.write(c); } } catch (InterruptedIOException x) { Thread.currentThread().interrupt(); } catch (IOException x) { trouble = true; } } /** * Writes A Portion of an array of characters. * @param buf Array of characters * @param off Offset from which to start writing characters * @param len Number of characters to write * * @throws IndexOutOfBoundsException * If the values of the {@code off} and {@code len} parameters * cause the corresponding method of the underlying {@code Writer} * to throw an {@code IndexOutOfBoundsException} */ public void write(char buf[], int off, int len) { try { synchronized (lock) { ensureOpen(); out.write(buf, off, len); } } catch (InterruptedIOException x) { Thread.currentThread().interrupt(); } catch (IOException x) { trouble = true; } } /** * Writes an array of characters. This method cannot be inherited from the * Writer class because it must suppress I/O exceptions. * @param buf Array of characters to be written */ public void write(char buf[]) { write(buf, 0, buf.length); } /** * Writes a portion of a string. * @param s A String * @param off Offset from which to start writing characters * @param len Number of characters to write * * @throws IndexOutOfBoundsException * If the values of the {@code off} and {@code len} parameters * cause the corresponding method of the underlying {@code Writer} * to throw an {@code IndexOutOfBoundsException} */ public void write(String s, int off, int len) { try { synchronized (lock) { ensureOpen(); out.write(s, off, len); } } catch (InterruptedIOException x) { Thread.currentThread().interrupt(); } catch (IOException x) { trouble = true; } } /** * Writes a string. This method cannot be inherited from the Writer class * because it must suppress I/O exceptions. * @param s String to be written */ public void write(String s) { write(s, 0, s.length()); } private void newLine() { try { synchronized (lock) { ensureOpen(); out.write(System.lineSeparator()); if (autoFlush) out.flush(); } } catch (InterruptedIOException x) { Thread.currentThread().interrupt(); } catch (IOException x) { trouble = true; } } /* Methods that do not terminate lines */ /** * Prints a boolean value. The string produced by {@link * java.lang.String#valueOf(boolean)} is translated into bytes * according to the platform's default character encoding, and these bytes * are written in exactly the manner of the {@link * #write(int)} method. * * @param b The {@code boolean} to be printed */ public void print(boolean b) { write(String.valueOf(b)); } /** * Prints a character. The character is translated into one or more bytes * according to the platform's default character encoding, and these bytes * are written in exactly the manner of the {@link * #write(int)} method. * * @param c The {@code char} to be printed */ public void print(char c) { write(c); } /** * Prints an integer. The string produced by {@link * java.lang.String#valueOf(int)} is translated into bytes according * to the platform's default character encoding, and these bytes are * written in exactly the manner of the {@link #write(int)} * method. * * @param i The {@code int} to be printed * @see java.lang.Integer#toString(int) */ public void print(int i) { write(String.valueOf(i)); } /** * Prints a long integer. The string produced by {@link * java.lang.String#valueOf(long)} is translated into bytes * according to the platform's default character encoding, and these bytes * are written in exactly the manner of the {@link #write(int)} * method. * * @param l The {@code long} to be printed * @see java.lang.Long#toString(long) */ public void print(long l) { write(String.valueOf(l)); } /** * Prints a floating-point number. The string produced by {@link * java.lang.String#valueOf(float)} is translated into bytes * according to the platform's default character encoding, and these bytes * are written in exactly the manner of the {@link #write(int)} * method. * * @param f The {@code float} to be printed * @see java.lang.Float#toString(float) */ public void print(float f) { write(String.valueOf(f)); } /** * Prints a double-precision floating-point number. The string produced by * {@link java.lang.String#valueOf(double)} is translated into * bytes according to the platform's default character encoding, and these * bytes are written in exactly the manner of the {@link * #write(int)} method. * * @param d The {@code double} to be printed * @see java.lang.Double#toString(double) */ public void print(double d) { write(String.valueOf(d)); } /** * Prints an array of characters. The characters are converted into bytes * according to the platform's default character encoding, and these bytes * are written in exactly the manner of the {@link #write(int)} * method. * * @param s The array of chars to be printed * * @throws NullPointerException If {@code s} is {@code null} */ public void print(char s[]) { write(s); } /** * Prints a string. If the argument is {@code null} then the string * {@code "null"} is printed. Otherwise, the string's characters are * converted into bytes according to the platform's default character * encoding, and these bytes are written in exactly the manner of the * {@link #write(int)} method. * * @param s The {@code String} to be printed */ public void print(String s) { write(String.valueOf(s)); } /** * Prints an object. The string produced by the {@link * java.lang.String#valueOf(Object)} method is translated into bytes * according to the platform's default character encoding, and these bytes * are written in exactly the manner of the {@link #write(int)} * method. * * @param obj The {@code Object} to be printed * @see java.lang.Object#toString() */ public void print(Object obj) { write(String.valueOf(obj)); } /* Methods that do terminate lines */ /** * Terminates the current line by writing the line separator string. The * line separator is {@link System#lineSeparator()} and is not necessarily * a single newline character ({@code '\n'}). */ public void println() { newLine(); } /** * Prints a boolean value and then terminates the line. This method behaves * as though it invokes {@link #print(boolean)} and then * {@link #println()}. * * @param x the {@code boolean} value to be printed */ public void println(boolean x) { synchronized (lock) { print(x); println(); } } /** * Prints a character and then terminates the line. This method behaves as * though it invokes {@link #print(char)} and then {@link * #println()}. * * @param x the {@code char} value to be printed */ public void println(char x) { synchronized (lock) { print(x); println(); } } /** * Prints an integer and then terminates the line. This method behaves as * though it invokes {@link #print(int)} and then {@link * #println()}. * * @param x the {@code int} value to be printed */ public void println(int x) { synchronized (lock) { print(x); println(); } } /** * Prints a long integer and then terminates the line. This method behaves * as though it invokes {@link #print(long)} and then * {@link #println()}. * * @param x the {@code long} value to be printed */ public void println(long x) { synchronized (lock) { print(x); println(); } } /** * Prints a floating-point number and then terminates the line. This method * behaves as though it invokes {@link #print(float)} and then * {@link #println()}. * * @param x the {@code float} value to be printed */ public void println(float x) { synchronized (lock) { print(x); println(); } } /** * Prints a double-precision floating-point number and then terminates the * line. This method behaves as though it invokes {@link * #print(double)} and then {@link #println()}. * * @param x the {@code double} value to be printed */ public void println(double x) { synchronized (lock) { print(x); println(); } } /** * Prints an array of characters and then terminates the line. This method * behaves as though it invokes {@link #print(char[])} and then * {@link #println()}. * * @param x the array of {@code char} values to be printed */ public void println(char x[]) { synchronized (lock) { print(x); println(); } } /** * Prints a String and then terminates the line. This method behaves as * though it invokes {@link #print(String)} and then * {@link #println()}. * * @param x the {@code String} value to be printed */ public void println(String x) { synchronized (lock) { print(x); println(); } } /** * Prints an Object and then terminates the line. This method calls * at first String.valueOf(x) to get the printed object's string value, * then behaves as * though it invokes {@link #print(String)} and then * {@link #println()}. * * @param x The {@code Object} to be printed. */ public void println(Object x) { String s = String.valueOf(x); synchronized (lock) { print(s); println(); } } /** * A convenience method to write a formatted string to this writer using * the specified format string and arguments. If automatic flushing is * enabled, calls to this method will flush the output buffer. * * <p> An invocation of this method of the form * {@code out.printf(format, args)} * behaves in exactly the same way as the invocation * * <pre>{@code * out.format(format, args) * }</pre> * * @param format * A format string as described in <a * href="../util/Formatter.html#syntax">Format string syntax</a>. * * @param args * Arguments referenced by the format specifiers in the format * string. If there are more arguments than format specifiers, the * extra arguments are ignored. The number of arguments is * variable and may be zero. The maximum number of arguments is * limited by the maximum dimension of a Java array as defined by * <cite>The Java™ Virtual Machine Specification</cite>. * The behaviour on a * {@code null} argument depends on the <a * href="../util/Formatter.html#syntax">conversion</a>. * * @throws java.util.IllegalFormatException * If a format string contains an illegal syntax, a format * specifier that is incompatible with the given arguments, * insufficient arguments given the format string, or other * illegal conditions. For specification of all possible * formatting errors, see the <a * href="../util/Formatter.html#detail">Details</a> section of the * formatter class specification. * * @throws NullPointerException * If the {@code format} is {@code null} * * @return This writer * * @since 1.5 */ public PrintWriter printf(String format, Object... args) { return format(format, args); } /** * A convenience method to write a formatted string to this writer using * the specified format string and arguments. If automatic flushing is * enabled, calls to this method will flush the output buffer. * * <p> An invocation of this method of the form * {@code out.printf(l, format, args)} * behaves in exactly the same way as the invocation * * <pre>{@code * out.format(l, format, args) * }</pre> * * @param l * The {@linkplain java.util.Locale locale} to apply during * formatting. If {@code l} is {@code null} then no localization * is applied. * * @param format * A format string as described in <a * href="../util/Formatter.html#syntax">Format string syntax</a>. * * @param args * Arguments referenced by the format specifiers in the format * string. If there are more arguments than format specifiers, the * extra arguments are ignored. The number of arguments is * variable and may be zero. The maximum number of arguments is * limited by the maximum dimension of a Java array as defined by * <cite>The Java™ Virtual Machine Specification</cite>. * The behaviour on a * {@code null} argument depends on the <a * href="../util/Formatter.html#syntax">conversion</a>. * * @throws java.util.IllegalFormatException * If a format string contains an illegal syntax, a format * specifier that is incompatible with the given arguments, * insufficient arguments given the format string, or other * illegal conditions. For specification of all possible * formatting errors, see the <a * href="../util/Formatter.html#detail">Details</a> section of the * formatter class specification. * * @throws NullPointerException * If the {@code format} is {@code null} * * @return This writer * * @since 1.5 */ public PrintWriter printf(Locale l, String format, Object... args) { return format(l, format, args); } /** * Writes a formatted string to this writer using the specified format * string and arguments. If automatic flushing is enabled, calls to this * method will flush the output buffer. * * <p> The locale always used is the one returned by {@link * java.util.Locale#getDefault() Locale.getDefault()}, regardless of any * previous invocations of other formatting methods on this object. * * @param format * A format string as described in <a * href="../util/Formatter.html#syntax">Format string syntax</a>. * * @param args * Arguments referenced by the format specifiers in the format * string. If there are more arguments than format specifiers, the * extra arguments are ignored. The number of arguments is * variable and may be zero. The maximum number of arguments is * limited by the maximum dimension of a Java array as defined by * <cite>The Java™ Virtual Machine Specification</cite>. * The behaviour on a * {@code null} argument depends on the <a * href="../util/Formatter.html#syntax">conversion</a>. * * @throws java.util.IllegalFormatException * If a format string contains an illegal syntax, a format * specifier that is incompatible with the given arguments, * insufficient arguments given the format string, or other * illegal conditions. For specification of all possible * formatting errors, see the <a * href="../util/Formatter.html#detail">Details</a> section of the * Formatter class specification. * * @throws NullPointerException * If the {@code format} is {@code null} * * @return This writer * * @since 1.5 */ public PrintWriter format(String format, Object... args) { try { synchronized (lock) { ensureOpen(); if ((formatter == null) || (formatter.locale() != Locale.getDefault())) formatter = new Formatter(this); formatter.format(Locale.getDefault(), format, args); if (autoFlush) out.flush(); } } catch (InterruptedIOException x) { Thread.currentThread().interrupt(); } catch (IOException x) { trouble = true; } return this; } /** * Writes a formatted string to this writer using the specified format * string and arguments. If automatic flushing is enabled, calls to this * method will flush the output buffer. * * @param l * The {@linkplain java.util.Locale locale} to apply during * formatting. If {@code l} is {@code null} then no localization * is applied. * * @param format * A format string as described in <a * href="../util/Formatter.html#syntax">Format string syntax</a>. * * @param args * Arguments referenced by the format specifiers in the format * string. If there are more arguments than format specifiers, the * extra arguments are ignored. The number of arguments is * variable and may be zero. The maximum number of arguments is * limited by the maximum dimension of a Java array as defined by * <cite>The Java™ Virtual Machine Specification</cite>. * The behaviour on a * {@code null} argument depends on the <a * href="../util/Formatter.html#syntax">conversion</a>. * * @throws java.util.IllegalFormatException * If a format string contains an illegal syntax, a format * specifier that is incompatible with the given arguments, * insufficient arguments given the format string, or other * illegal conditions. For specification of all possible * formatting errors, see the <a * href="../util/Formatter.html#detail">Details</a> section of the * formatter class specification. * * @throws NullPointerException * If the {@code format} is {@code null} * * @return This writer * * @since 1.5 */ public PrintWriter format(Locale l, String format, Object... args) { try { synchronized (lock) { ensureOpen(); if ((formatter == null) || (formatter.locale() != l)) formatter = new Formatter(this, l); formatter.format(l, format, args); if (autoFlush) out.flush(); } } catch (InterruptedIOException x) { Thread.currentThread().interrupt(); } catch (IOException x) { trouble = true; } return this; } /** * Appends the specified character sequence to this writer. * * <p> An invocation of this method of the form {@code out.append(csq)} * behaves in exactly the same way as the invocation * * <pre>{@code * out.write(csq.toString()) * }</pre> * * <p> Depending on the specification of {@code toString} for the * character sequence {@code csq}, the entire sequence may not be * appended. For instance, invoking the {@code toString} method of a * character buffer will return a subsequence whose content depends upon * the buffer's position and limit. * * @param csq * The character sequence to append. If {@code csq} is * {@code null}, then the four characters {@code "null"} are * appended to this writer. * * @return This writer * * @since 1.5 */ public PrintWriter append(CharSequence csq) { write(String.valueOf(csq)); return this; } /** * Appends a subsequence of the specified character sequence to this writer. * * <p> An invocation of this method of the form * {@code out.append(csq, start, end)} * when {@code csq} is not {@code null}, behaves in * exactly the same way as the invocation * * <pre>{@code * out.write(csq.subSequence(start, end).toString()) * }</pre> * * @param csq * The character sequence from which a subsequence will be * appended. If {@code csq} is {@code null}, then characters * will be appended as if {@code csq} contained the four * characters {@code "null"}. * * @param start * The index of the first character in the subsequence * * @param end * The index of the character following the last character in the * subsequence * * @return This writer * * @throws IndexOutOfBoundsException * If {@code start} or {@code end} are negative, {@code start} * is greater than {@code end}, or {@code end} is greater than * {@code csq.length()} * * @since 1.5 */ public PrintWriter append(CharSequence csq, int start, int end) { if (csq == null) csq = "null"; return append(csq.subSequence(start, end)); } /** * Appends the specified character to this writer. * * <p> An invocation of this method of the form {@code out.append(c)} * behaves in exactly the same way as the invocation * * <pre>{@code * out.write(c) * }</pre> * * @param c * The 16-bit character to append * * @return This writer * * @since 1.5 */ public PrintWriter append(char c) { write(c); return this; } }