|
Java example source code file (PrintWriter.java)
The PrintWriter.java Java example source code/* * Copyright (c) 1996, 2012, 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 <tt>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 <tt>println, printf, or * <tt>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()}. * * @author Frank Yellin * @author Mark Reinhold * @since JDK1.1 */ 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; /** * Line separator string. This is the value of the line.separator * property at the moment that the stream was created. */ private final String lineSeparator; /** * 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 <tt>println, * <tt>printf, or format methods will * flush the output buffer */ public PrintWriter(Writer out, boolean autoFlush) { super(out); this.out = out; this.autoFlush = autoFlush; lineSeparator = java.security.AccessController.doPrivileged( new sun.security.action.GetPropertyAction("line.separator")); } /** * 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 <tt>println, * <tt>printf, or format methods will * flush the output buffer * * @see java.io.OutputStreamWriter#OutputStreamWriter(java.io.OutputStream) */ public PrintWriter(OutputStream out, boolean autoFlush) { this(new BufferedWriter(new OutputStreamWriter(out)), 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. 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); } /** 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 <tt>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 <tt>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 */ 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 */ 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(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 <code>{@link * java.lang.String#valueOf(boolean)}</code> is translated into bytes * according to the platform's default character encoding, and these bytes * are written in exactly the manner of the <code>{@link * #write(int)}</code> method. * * @param b The <code>boolean to be printed */ public void print(boolean b) { write(b ? "true" : "false"); } /** * 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 <code>{@link * #write(int)}</code> method. * * @param c The <code>char to be printed */ public void print(char c) { write(c); } /** * Prints an integer. The string produced by <code>{@link * java.lang.String#valueOf(int)}</code> is translated into bytes according * to the platform's default character encoding, and these bytes are * written in exactly the manner of the <code>{@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 <code>{@link * java.lang.String#valueOf(long)}</code> is translated into bytes * according to the platform's default character encoding, and these bytes * are written in exactly the manner of the <code>{@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 <code>{@link * java.lang.String#valueOf(float)}</code> is translated into bytes * according to the platform's default character encoding, and these bytes * are written in exactly the manner of the <code>{@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 * <code>{@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 <code>{@link * #write(int)}</code> 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 <code>{@link #write(int)} * method. * * @param s The array of chars to be printed * * @throws NullPointerException If <code>s is |
... this post is sponsored by my books ... | |
#1 New Release! |
FP Best Seller |
Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.
A percentage of advertising revenue from
pages under the /java/jwarehouse
URI on this website is
paid back to open source projects.