InputStream

// Create class TextInputStream which subclasses InputStream and implements
// read() as required.  This basic class will be used in the next four demos
// when connecting to other Java supplied classes to build a needed set of
// services for accessing an input stream.  The TextInputStream class is 
// simple: a JFrame is opened and a KeyListener is attached - when a key is 
// pressed while the JFrame is in focus, the corresponding key code is sent
// into the stream.  In this example we take the codes directly from the
// TextInputStream object and print them raw onto another "Output" JFrame.
//
// The following is in file TextInputStream.java
import java.io.InputStream;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

class TextFrame extends Frame implements KeyListener {
   JTextArea text;
   int chr;
   boolean char_ready;
   int i=1;
   
   TextFrame () {
      setLayout(new BorderLayout());
      add ("North", new Label("Input Stream"));
      add ("Center", new JScrollPane(text = new JTextArea(20,30)));
      text.addKeyListener(this);
      setSize(300,300);
      setVisible(true);
   }

   public void keyReleased (KeyEvent e) { }
   
   public void keyPressed (KeyEvent e) { }   

   // The thread that will own this method is the AWT-EventQueue
   // This method is invoked when a key is typed while the TextFrame 
   // object is in focus.
   synchronized public void keyTyped (KeyEvent e) {
      if (char_ready) return;
      if (i++ == 30) { text.append ("\n"); i = 0; }
      chr = (int)e.getKeyChar();
      char_ready = true;
      notify();
   }

   // The thread that will own this is the Applet (InputStreamTest object)   
   synchronized int read () {
      if (!char_ready) try { wait (); } catch (Exception e) { }
      char_ready = false;
      return chr;
   }
}

// Required to implement the read() method.  We also implement read(byte[] chr)
// in advance of its being needed for the BufferedReader test that will be 
// made later.
class TextInputStream extends InputStream {
   TextFrame tf;
   
   TextInputStream () { tf = new TextFrame(); }
   
   public int read () { return tf.read(); }

   public int read(byte[] chr) { chr[0] = (byte)tf.read(); return 1; }
}

// The following is in file InputStreamTest.java.  This is where the above
// class is used
import java.awt.*;
import javax.swing.*;
import java.applet.*;

class InputStreamFrame extends JFrame implements Runnable {
   JTextArea out;
   Thread runner;
	
   public InputStreamFrame () {
      setLayout(new BorderLayout());
      add ("North", new JLabel("Output", JLabel.CENTER));
      add ("Center", new JScrollPane(out = new JTextArea(20,25)));
      setVisible(true);
   }

   public void start () {
      runner = new Thread(this);
      runner.start();
   }

   public void run () {
      TextInputStream is = new TextInputStream();
      try {
         for (int i=1 ; ; i++) {
            int in = is.read();
            out.append(in+" ");
            if (i == 7) { out.append ("\n"); i = 0; }
         }
      }
      catch (Exception e) { out.append ("\n"+e); }
   }

   public void finalize () throws Throwable { super.finalize(); }
}

public class InputStreamTest extends Applet {
   public void init () {
      InputStreamFrame inp = new InputStreamFrame();
      inp.setSize(300,300);
      inp.setVisible(true);
      inp.start();
   }
}