All Downloads are FREE. Search and download functionalities are using the official Maven repository.

java.io.PrintWriter Maven / Gradle / Ivy

Go to download

JVM AOT compiler currently generating JavaScript, C++, Haxe, with initial focus on Kotlin and games.

There is a newer version: 0.6.8
Show newest version
/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package java.io;

import java.util.Formatter;
import java.util.IllegalFormatException;
import java.util.Locale;

/**
 * Wraps either an existing {@link OutputStream} or an existing {@link Writer}
 * and provides convenience methods for printing common data types in a human
 * readable format. No {@code IOException} is thrown by this class. Instead,
 * callers should use {@link #checkError()} to see if a problem has occurred in
 * this writer.
 */
public class PrintWriter extends Writer {
    /**
     * The writer to print data to.
     */
    protected Writer out;

    /**
     * Indicates whether this PrintWriter is in an error state.
     */
    private boolean ioError;

    /**
     * Indicates whether or not this PrintWriter should flush its contents after
     * printing a new line.
     */
    private boolean autoFlush;

    /**
     * Constructs a new {@code PrintWriter} with {@code out} as its target
     * stream. By default, the new print writer does not automatically flush its
     * contents to the target stream when a newline is encountered.
     *
     * @param out
     *            the target output stream.
     * @throws NullPointerException
     *             if {@code out} is {@code null}.
     */
    public PrintWriter(OutputStream out) {
        this(new OutputStreamWriter(out), false);
    }

    /**
     * Constructs a new {@code PrintWriter} with {@code out} as its target
     * stream. The parameter {@code autoFlush} determines if the print writer
     * automatically flushes its contents to the target stream when a newline is
     * encountered.
     *
     * @param out
     *            the target output stream.
     * @param autoFlush
     *            indicates whether contents are flushed upon encountering a
     *            newline sequence.
     * @throws NullPointerException
     *             if {@code out} is {@code null}.
     */
    public PrintWriter(OutputStream out, boolean autoFlush) {
        this(new OutputStreamWriter(out), autoFlush);
    }

    /**
     * Constructs a new {@code PrintWriter} with {@code wr} as its target
     * writer. By default, the new print writer does not automatically flush its
     * contents to the target writer when a newline is encountered.
     *
     * @param wr
     *            the target writer.
     * @throws NullPointerException
     *             if {@code wr} is {@code null}.
     */
    public PrintWriter(Writer wr) {
        this(wr, false);
    }

    /**
     * Constructs a new {@code PrintWriter} with {@code out} as its target
     * writer. The parameter {@code autoFlush} determines if the print writer
     * automatically flushes its contents to the target writer when a newline is
     * encountered.
     *
     * @param wr
     *            the target writer.
     * @param autoFlush
     *            indicates whether to flush contents upon encountering a
     *            newline sequence.
     * @throws NullPointerException
     *             if {@code out} is {@code null}.
     */
    public PrintWriter(Writer wr, boolean autoFlush) {
        super(wr);
        this.autoFlush = autoFlush;
        out = wr;
    }

    /**
     * Constructs a new {@code PrintWriter} with {@code file} as its target. The
     * VM's default character set is used for character encoding.
     * The print writer does not automatically flush its contents to the target
     * file when a newline is encountered. The output to the file is buffered.
     *
     * @param file
     *            the target file. If the file already exists, its contents are
     *            removed, otherwise a new file is created.
     * @throws FileNotFoundException
     *             if an error occurs while opening or creating the target file.
     */
    public PrintWriter(File file) throws FileNotFoundException {
        this(new OutputStreamWriter(new BufferedOutputStream(new FileOutputStream(file))), false);
    }

    /**
     * Constructs a new {@code PrintWriter} with {@code file} as its target. The
     * character set named {@code csn} is used for character encoding.
     * The print writer does not automatically flush its contents to the target
     * file when a newline is encountered. The output to the file is buffered.
     *
     * @param file
     *            the target file. If the file already exists, its contents are
     *            removed, otherwise a new file is created.
     * @param csn
     *            the name of the character set used for character encoding.
     * @throws FileNotFoundException
     *             if an error occurs while opening or creating the target file.
     * @throws NullPointerException
     *             if {@code csn} is {@code null}.
     * @throws UnsupportedEncodingException
     *             if the encoding specified by {@code csn} is not supported.
     */
    public PrintWriter(File file, String csn) throws FileNotFoundException,
            UnsupportedEncodingException {
        this(new OutputStreamWriter(new BufferedOutputStream(new FileOutputStream(file)), csn),
                false);
    }

    /**
     * Constructs a new {@code PrintWriter} with the file identified by {@code
     * fileName} as its target. The VM's default character set is
     * used for character encoding. The print writer does not automatically
     * flush its contents to the target file when a newline is encountered. The
     * output to the file is buffered.
     *
     * @param fileName
     *            the target file's name. If the file already exists, its
     *            contents are removed, otherwise a new file is created.
     * @throws FileNotFoundException
     *             if an error occurs while opening or creating the target file.
     */
    public PrintWriter(String fileName) throws FileNotFoundException {
        this(new OutputStreamWriter(new BufferedOutputStream(new FileOutputStream(fileName))),
                false);
    }

     /**
     * Constructs a new {@code PrintWriter} with the file identified by {@code
     * fileName} as its target. The character set named {@code csn} is used for
     * character encoding. The print writer does not automatically flush its
     * contents to the target file when a newline is encountered. The output to
     * the file is buffered.
     *
     * @param fileName
     *            the target file's name. If the file already exists, its
     *            contents are removed, otherwise a new file is created.
     * @param csn
     *            the name of the character set used for character encoding.
     * @throws FileNotFoundException
     *             if an error occurs while opening or creating the target file.
     * @throws NullPointerException
     *             if {@code csn} is {@code null}.
     * @throws UnsupportedEncodingException
     *             if the encoding specified by {@code csn} is not supported.
     */
    public PrintWriter(String fileName, String csn)
            throws FileNotFoundException, UnsupportedEncodingException {
        this(new OutputStreamWriter(new BufferedOutputStream(new FileOutputStream(fileName)), csn),
                false);
    }

    /**
     * Flushes this writer and returns the value of the error flag.
     *
     * @return {@code true} if either an {@code IOException} has been thrown
     *         previously or if {@code setError()} has been called;
     *         {@code false} otherwise.
     * @see #setError()
     */
    public boolean checkError() {
        Writer delegate = out;
        if (delegate == null) {
            return ioError;
        }

        flush();
        return ioError || delegate.checkError();
    }

    /**
     * Sets the error state of the stream to false.
     * @since 1.6
     */
    protected void clearError() {
        synchronized (lock) {
            ioError = false;
        }
    }

    /**
     * Closes this print writer. Flushes this writer and then closes the target.
     * If an I/O error occurs, this writer's error flag is set to {@code true}.
     */
    @Override
    public void close() {
        synchronized (lock) {
            if (out != null) {
                try {
                    out.close();
                } catch (IOException e) {
                    setError();
                }
                out = null;
            }
        }
    }

    /**
     * Ensures that all pending data is sent out to the target. It also
     * flushes the target. If an I/O error occurs, this writer's error
     * state is set to {@code true}.
     */
    @Override
    public void flush() {
        synchronized (lock) {
            if (out != null) {
                try {
                    out.flush();
                } catch (IOException e) {
                    setError();
                }
            } else {
                setError();
            }
        }
    }

    /**
     * Formats {@code args} according to the format string {@code format}, and writes the result
     * to this stream. This method uses the user's default locale.
     * See "Be wary of the default locale".
     * If automatic flushing is enabled then the buffer is flushed as well.
     *
     * @param format the format string (see {@link Formatter#format})
     * @param args
     *            the list of arguments passed to the formatter. If there are
     *            more arguments than required by {@code format},
     *            additional arguments are ignored.
     * @return this writer.
     * @throws IllegalFormatException
     *             if the format string is illegal or incompatible with the
     *             arguments, if there are not enough arguments or if any other
     *             error regarding the format string or arguments is detected.
     * @throws NullPointerException if {@code format == null}
     */
    public PrintWriter format(String format, Object... args) {
        return format(Locale.getDefault(), format, args);
    }

    /**
     * Writes a string formatted by an intermediate {@code Formatter} to the
     * target using the specified locale, format string and arguments. If
     * automatic flushing is enabled then this writer is flushed.
     *
     * @param l
     *            the locale used in the method. No localization will be applied
     *            if {@code l} is {@code null}.
     * @param format the format string (see {@link Formatter#format})
     * @param args
     *            the list of arguments passed to the formatter. If there are
     *            more arguments than required by {@code format},
     *            additional arguments are ignored.
     * @return this writer.
     * @throws IllegalFormatException
     *             if the format string is illegal or incompatible with the
     *             arguments, if there are not enough arguments or if any other
     *             error regarding the format string or arguments is detected.
     * @throws NullPointerException if {@code format == null}
     */
    public PrintWriter format(Locale l, String format, Object... args) {
        if (format == null) {
            throw new NullPointerException("format == null");
        }
        new Formatter(this, l).format(format, args);
        if (autoFlush) {
            flush();
        }
        return this;
    }

    /**
     * Prints a formatted string. The behavior of this method is the same as
     * this writer's {@code #format(String, Object...)} method.
     *
     * 

The {@code Locale} used is the user's default locale. * See "Be wary of the default locale". * * @param format the format string (see {@link Formatter#format}) * @param args * the list of arguments passed to the formatter. If there are * more arguments than required by {@code format}, * additional arguments are ignored. * @return this writer. * @throws IllegalFormatException * if the format string is illegal or incompatible with the * arguments, if there are not enough arguments or if any other * error regarding the format string or arguments is detected. * @throws NullPointerException if {@code format == null} */ public PrintWriter printf(String format, Object... args) { return format(format, args); } /** * Prints a formatted string. The behavior of this method is the same as * this writer's {@code #format(Locale, String, Object...)} method. * * @param l * the locale used in the method. No localization will be applied * if {@code l} is {@code null}. * @param format the format string (see {@link Formatter#format}) * @param args * the list of arguments passed to the formatter. If there are * more arguments than required by {@code format}, * additional arguments are ignored. * @return this writer. * @throws IllegalFormatException * if the format string is illegal or incompatible with the * arguments, if there are not enough arguments or if any other * error regarding the format string or arguments is detected. * @throws NullPointerException if {@code format == null} */ public PrintWriter printf(Locale l, String format, Object... args) { return format(l, format, args); } /** * Prints the string representation of the specified character array * to the target. * * @param charArray * the character array to print to the target. * @see #print(String) */ public void print(char[] charArray) { print(new String(charArray, 0, charArray.length)); } /** * Prints the string representation of the specified character to the * target. * * @param ch * the character to print to the target. * @see #print(String) */ public void print(char ch) { print(String.valueOf(ch)); } /** * Prints the string representation of the specified double to the target. * * @param dnum * the double value to print to the target. * @see #print(String) */ public void print(double dnum) { print(String.valueOf(dnum)); } /** * Prints the string representation of the specified float to the target. * * @param fnum * the float value to print to the target. * @see #print(String) */ public void print(float fnum) { print(String.valueOf(fnum)); } /** * Prints the string representation of the specified integer to the target. * * @param inum * the integer value to print to the target. * @see #print(String) */ public void print(int inum) { print(String.valueOf(inum)); } /** * Prints the string representation of the specified long to the target. * * @param lnum * the long value to print to the target. * @see #print(String) */ public void print(long lnum) { print(String.valueOf(lnum)); } /** * Prints the string representation of the specified object to the target. * * @param obj * the object to print to the target. * @see #print(String) */ public void print(Object obj) { print(String.valueOf(obj)); } /** * Prints a string to the target. The string is converted to an array of * bytes using the encoding chosen during the construction of this writer. * The bytes are then written to the target with {@code write(int)}. *

* If an I/O error occurs, this writer's error flag is set to {@code true}. * * @param str * the string to print to the target. * @see #write(int) */ public void print(String str) { write(str != null ? str : String.valueOf((Object) null)); } /** * Prints the string representation of the specified boolean to the target. * * @param bool * the boolean value to print the target. * @see #print(String) */ public void print(boolean bool) { print(String.valueOf(bool)); } /** * Prints a newline. Flushes this writer if the autoFlush flag is set to {@code true}. */ public void println() { synchronized (lock) { print(System.lineSeparator()); if (autoFlush) { flush(); } } } /** * Prints the string representation of the character array {@code chars} followed by a newline. * Flushes this writer if the autoFlush flag is set to {@code true}. */ public void println(char[] chars) { println(new String(chars, 0, chars.length)); } /** * Prints the string representation of the char {@code c} followed by a newline. * Flushes this writer if the autoFlush flag is set to {@code true}. */ public void println(char c) { println(String.valueOf(c)); } /** * Prints the string representation of the double {@code d} followed by a newline. * Flushes this writer if the autoFlush flag is set to {@code true}. */ public void println(double d) { println(String.valueOf(d)); } /** * Prints the string representation of the float {@code f} followed by a newline. * Flushes this writer if the autoFlush flag is set to {@code true}. */ public void println(float f) { println(String.valueOf(f)); } /** * Prints the string representation of the int {@code i} followed by a newline. * Flushes this writer if the autoFlush flag is set to {@code true}. */ public void println(int i) { println(String.valueOf(i)); } /** * Prints the string representation of the long {@code l} followed by a newline. * Flushes this writer if the autoFlush flag is set to {@code true}. */ public void println(long l) { println(String.valueOf(l)); } /** * Prints the string representation of the object {@code o}, or {@code "null}, * followed by a newline. * Flushes this writer if the autoFlush flag is set to {@code true}. */ public void println(Object obj) { println(String.valueOf(obj)); } /** * Prints the string representation of the string {@code s} followed by a newline. * Flushes this writer if the autoFlush flag is set to {@code true}. * *

The string is converted to an array of bytes using the * encoding chosen during the construction of this writer. The bytes are * then written to the target with {@code write(int)}. Finally, this writer * is flushed if the autoFlush flag is set to {@code true}. * *

If an I/O error occurs, this writer's error flag is set to {@code true}. */ public void println(String str) { synchronized (lock) { print(str); println(); } } /** * Prints the string representation of the boolean {@code b} followed by a newline. * Flushes this writer if the autoFlush flag is set to {@code true}. */ public void println(boolean b) { println(String.valueOf(b)); } /** * Sets the error flag of this writer to true. */ protected void setError() { synchronized (lock) { ioError = true; } } /** * Writes the character buffer {@code buf} to the target. * * @param buf * the non-null array containing characters to write. */ @Override public void write(char[] buf) { write(buf, 0, buf.length); } /** * Writes {@code count} characters from {@code buffer} starting at {@code * offset} to the target. *

* This writer's error flag is set to {@code true} if this writer is closed * or an I/O error occurs. * * @param buf * the buffer to write to the target. * @param offset * the index of the first character in {@code buffer} to write. * @param count * the number of characters in {@code buffer} to write. * @throws IndexOutOfBoundsException * if {@code offset < 0} or {@code count < 0}, or if {@code * offset + count} is greater than the length of {@code buf}. */ @Override public void write(char[] buf, int offset, int count) { doWrite(buf, offset, count); } /** * Writes one character to the target. Only the two least significant bytes * of the integer {@code oneChar} are written. *

* This writer's error flag is set to {@code true} if this writer is closed * or an I/O error occurs. * * @param oneChar * the character to write to the target. */ @Override public void write(int oneChar) { doWrite(new char[] { (char) oneChar }, 0, 1); } private final void doWrite(char[] buf, int offset, int count) { synchronized (lock) { if (out != null) { try { out.write(buf, offset, count); } catch (IOException e) { setError(); } } else { setError(); } } } /** * Writes the characters from the specified string to the target. * * @param str * the non-null string containing the characters to write. */ @Override public void write(String str) { write(str.toCharArray()); } /** * Writes {@code count} characters from {@code str} starting at {@code * offset} to the target. * * @param str * the non-null string containing the characters to write. * @param offset * the index of the first character in {@code str} to write. * @param count * the number of characters from {@code str} to write. * @throws IndexOutOfBoundsException * if {@code offset < 0} or {@code count < 0}, or if {@code * offset + count} is greater than the length of {@code str}. */ @Override public void write(String str, int offset, int count) { write(str.substring(offset, offset + count).toCharArray()); } /** * Appends the character {@code c} to the target. * * @param c * the character to append to the target. * @return this writer. */ @Override public PrintWriter append(char c) { write(c); return this; } /** * Appends the character sequence {@code csq} to the target. This * method works the same way as {@code PrintWriter.print(csq.toString())}. * If {@code csq} is {@code null}, then the string "null" is written * to the target. * * @param csq * the character sequence appended to the target. * @return this writer. */ @Override public PrintWriter append(CharSequence csq) { if (csq == null) { csq = "null"; } append(csq, 0, csq.length()); return this; } /** * Appends a subsequence of the character sequence {@code csq} to the * target. This method works the same way as {@code * PrintWriter.print(csq.subsequence(start, end).toString())}. If {@code * csq} is {@code null}, then the specified subsequence of the string "null" * will be written to the target. * * @param csq * the character sequence appended to the target. * @param start * the index of the first char in the character sequence appended * to the target. * @param end * the index of the character following the last character of the * subsequence appended to the target. * @return this writer. * @throws StringIndexOutOfBoundsException * if {@code start > end}, {@code start < 0}, {@code end < 0} or * either {@code start} or {@code end} are greater or equal than * the length of {@code csq}. */ @Override public PrintWriter append(CharSequence csq, int start, int end) { if (csq == null) { csq = "null"; } String output = csq.subSequence(start, end).toString(); write(output, 0, output.length()); return this; } }





© 2015 - 2024 Weber Informatics LLC | Privacy Policy