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Java in a Nutshell

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24.53 java.io.PrintWriter (JDK 1.1)

This class is a character output stream that implements a number of print() and println() methods that output textual representations of primitive values and objects. When you create a PrintWriter object, you specify a character or byte output stream that it should write its characters to, and also optionally specify whether the PrintWriter stream should be automatically flushed whenever println() is called. If you specify a byte output stream as the destination, the PrintWriter() constructor automatically creates the necessary OutputStreamWriter object to convert characters to bytes using the default encoding.

PrintWriter implements the normal write(), flush(), and close() methods that all Writer subclasses do. It is more common to use the higher-level print() and println() methods, each of which converts its argument to a string before outputting it. println() has the additional behavior of terminating the line (and optionally flushing the buffer) after printing its argument.

The methods of PrintWriter never throw exceptions. Instead, when errors occur, they set an internal flag that you can check by calling checkError(). checkError() first flushes the internal stream, and then returns true if any exception has occurred while writing values to that stream. Once an error has occurred on a PrintWriter object, all subsequent calls to checkError() return true; there is no way to reset the error flag.

PrintWriter is the character stream analog to PrintStream, which it supersedes. You can usually trivially replace any PrintStream objects in a program with PrintWriter objects. This is particularly important for internationalized programs. The only valid remaining use for the PrintStream class is for the System.out and System.err standard output streams. See PrintStream for details.

public class PrintWriter extends Writer {
    // Public Constructors
            public PrintWriter(Writer out);
            public PrintWriter(Writer out, boolean autoFlush);
            public PrintWriter(OutputStream out);
            public PrintWriter(OutputStream out, boolean autoFlush);
    // Public Instance Methods
            public boolean checkError();
            public void close();  // Defines Writer
            public void flush();  // Defines Writer
            public void print(boolean b);
            public void print(char c);
            public void print(int i);
            public void print(long l);
            public void print(float f);
            public void print(double d);
            public void print(char[] s);
            public void print(String s);
            public void print(Object obj);
            public void println();
            public void println(boolean x);
            public void println(char x);
            public void println(int x);
            public void println(long x);
            public void println(float x);
            public void println(double x);
            public void println(char[] x);
            public void println(String x);
            public void println(Object x);
            public void write(int c);  // Overrides Writer
            public void write(char[] buf, int off, int len);  // Defines Writer
            public void write(char[] buf);  // Overrides Writer
            public void write(String s, int off, int len);  // Overrides Writer
            public void write(String s);  // Overrides Writer
    // Protected Instance Methods
            protected void setError();
}

Hierarchy:

Object->Writer->PrintWriter

Passed To:

Component.list(), Container.list(), Properties.list(), Throwable.printStackTrace()


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