exceptiontest.java

有关布局安排的一个小程序

import java.awt.*;
import java.lang.*;
import java.awt.event.*;
public class ExceptionTest extends Frame implements ActionListener
{
	private TextArea ta;
	public static void main(String args[])
	{
		ExceptionTest test=new ExceptionTest();
		Button b1=new Button("安全 ");
		Button b2=new Button("危险");
		b1.addActionListener(test);
		b2.addActionListener(test);
		test.setLayout(new GridLayout(3,1));
		test.add(b1);
		test.add(b2);
		test.ta=new TextArea(null,10,20,TextArea.SCROLLBARS_VERTICAL_ONLY);
		test.add(test.ta);
		test.setSize(300,200);
		test.setVisible(true);
	}
 
    private void CheckButton(String Label)throws TextException
    {
    	if(Label.compareTo("危险")==0)
    	throw(new TextException());
    }
    public void actionPerformed(ActionEvent e)
    {
    	try
    	{
    		CheckButton(((Button)e.getSource()).getLabel());
    		ta.append("Safe\n");
    		
    	}
    	catch(TextException ex)
    	{
    		ta.append(ex.getMessage()+"\n");
    		
    		
    	}
    }
 }
 class TextException extends Exception
 {
 	public String getMessage()
 	{
 		return("This is a test exception.");
 	}
 }