Character by Character input

[Muralidhar Krishnamoorthy]

Hi
I just wanted to know if it is possible to get input character by character and then display it on the screen.Im right now working on a calculator like program which uses a similar LED display system. It requires the user to enter the numbers (digit after digit) and display it on the LED Panel as and when a keystroke is made.Also it shud accept Mouse Clicks from the Buttons Panel and add the digit clicked to the already entered number and be displayed on the LED Panel.
If any one can think of a solution to this please post it here
Reg
Muralidhar

[Vlad Patryshev]

The answer is: use Swing, not file i/o. You already have gui controls, right?

[Manfred Leonhardt]

Hi ,
The following code does what you want in a simple manner.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Calculator extends JFrame
{
  JButton b;
  JTextField tf;
  public Calculator()
  {
    Container cont = getContentPane();
    JPanel gl = new JPanel( new GridLayout( 3, 3 ) );
    for( int i = 1; i < 10; ++i )
    {
      b = new JButton( ""+i );
      b.setActionCommand( ""+i );
      b.addActionListener(
        new ActionListener()
        {
          public void actionPerformed( ActionEvent ae )
          {
            JButton b = (JButton)ae.getSource();
            appendChar( b.getText().charAt( 0 ) );
          }
        });
      b.addKeyListener(
        new KeyAdapter()
        {
          public void keyTyped( KeyEvent ke )
          {
            HandleKeyEvent( ke );
          }
        });
      gl.add( b );
    }
    tf = new JTextField( 20 );
    tf.setHorizontalAlignment( JTextField.RIGHT );
    tf.setEditable( false );
    tf.addKeyListener(
      new KeyAdapter()
      {
        public void keyTyped( KeyEvent ke )
        {
          HandleKeyEvent( ke );
        }
      });
    cont.add( tf, BorderLayout.NORTH );
    cont.add( gl, BorderLayout.CENTER );
    pack();
  }
  public void appendChar( char c )
  {
    System.out.println( c );
    String currStr = tf.getText();
    if( c == '.' )
    {
      if( currStr.indexOf( '.' ) < 0 )
      {
        tf.setText( currStr + c );
      }
    }
    else
    {
      tf.setText( currStr + c );
    }
  }
  public void HandleKeyEvent( KeyEvent ke )
  {
    char c = ke.getKeyChar();
    if( Character.isDigit( c ) | | c == '.' )
    {
      appendChar( c );
    }
  }
  public static void main(String[] args) 
  {
    Calculator c = new Calculator();
    c.addWindowListener(
      new WindowAdapter()
      {
        public void windowClosing( WindowEvent we )
        {
          System.exit( 0 );
        }
      });
    c.setVisible( true );
    c.b.requestFocus();
  }
}

Enjoy,
Manfred.