mouseEntered method

[linus dale]

import  java.awt.*;
import java.awt.event.*;

public class  TestII   extends  Frame

{

public TestII()
{


super("buton  example");
Button b1,b2,b3;
Panel p;
Label l;


System.out.println("testing");
b1=new Button("A");
b2=new Button("B");
 b3=new Button("C");
p=new Panel(new FlowLayout());
p.add(b1);
p.add(b2);
p.add(b3);
this.add(p,BorderLayout.NORTH);
l=new Label("some  label");
msHandler  h=new msHandler(l);
b1.addMouseListener(h);
b2.addMouseListener(h);
b3.addMouseListener(h);
this.add(l,BorderLayout.SOUTH);

}

public static void main(String args[])  throws Exception
{ TestII t;
   t=new TestII();
t.setSize(300,200);
t.setVisible(true);
t.addWindowListener(

new WindowAdapter()
{  public  void windowClosing(WindowEvent er)
{  System.exit(0);}

}

);

}
}


class msHandler extends MouseAdapter

{
Label lb;

public msHandler(Label l1)
{lb=l1;

}
public  void  mouseEntered(MouseEvent e)
{
Button b=((Button)e.getSource());

lb.setText("Mouse is over      "+b.getLabel());
}

public  void  mouseExited(MouseEvent e)
{ lb.setText("mouse exited ");
}
}

doubt
line no. 68 to 69
is this
Button b=((Button)e.getSource());
typecasting
what does this line do?
what is the use of getSource,getLabel,setText

[K. Tsang]

For events like mouse events, e.getSource() refers to component which fired the event. So say if you have a button and attach a MouseListener to it like below .... then the MouseEvent e.getSource would be a Button.

//using Swing rather than AWT
JButton button = new JButton("button1");
button.addMouseListener(new ButtonMouseListener());

class ButtonMouseListener implements MouseListener  {
// pretty much the same code you have msHandler
}

The casting is make sure the event is indeed a button and not object.

[Rob Spoor]

Linus, you've been asking quite a few starter questions lately. Perhaps it is a good idea to read through the Java Tutorial. This particular subject is discussed in its Swing section mostly.

[Campbell Ritchie]

Rob Prime wrote:This particular subject is discussed in its Swing section mostly.

Agree. Moving.

[linus dale]

Rob Prime wrote:Linus, you've been asking quite a few starter questions lately. Perhaps it is a good idea to read through the Java Tutorial. This particular subject is discussed in its Swing section mostly.

thanks
problem is I am a not much of a reader