Graphical User Interfaces - Java - page 575

Discussion

This is such a common need that I've added it to the DarwinSys package (see Downloading
and Using the Code Examples ). Here is the code for com.darwinsys.io.TextAreaWriter :

package package com . darwinsys . io ;

import import java.io.IOException java.io.IOException ;

import import java.io.Writer java.io.Writer ;

import import javax.swing.JTextArea javax.swing.JTextArea ;

/**
* Simple way to "print" to a JTextArea; just say
* PrintWriter out = new PrintWriter(new TextAreaWriter(myTextArea));
* Then out.println() et all will all appear in the TextArea.
*/
public public final final class class TextAreaWriter TextAreaWriter extends extends Writer {

private private final final JTextArea textArea ;

public public TextAreaWriter ( final final JTextArea textArea ) {

this this . textArea = textArea ;

}

@Override
public public void void flush (){ }

@Override
public public void void close (){ }

@Override
public

public void void write ( char char [] cbuf , int int off , int int len ) throws throws IOException {

textArea . append ( new new String ( cbuf , off , len ));

}

}

As you can see, for the Writer case I only had to override one write() form; all the other
forms of write() , and the print() / println() methods in PrintWriter , call down through
this one method. The flush() and close() methods are also abstract in Writer , but they
don't have to do anything here (though close() could set the textArea field to null , and
write() could check that, to guard against use of a closed Writer ).