guidemo9.java

java程序设计语言源代码

//Example 9 of Chapter 5

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class GUIDemo9
{
	public static void main( String args[] )
	{
		TextFieldTest application = new TextFieldTest();
	}
}

class TextFieldTest extends JFrame
{
	private JTextField textfield;
	private JTextArea textarea;
	private JPanel panel;
	private JButton button1,button2,button3;
	
	public TextFieldTest()
	{
		super( "输入显示测试" );
		
		Container container = getContentPane();
		container.setLayout( new BorderLayout() );
		
		textfield = new JTextField( );
		container.add( textfield , BorderLayout.NORTH);
		
		textarea = new JTextArea( 6, 30);
		textarea.setEditable( false );
		textarea.setLineWrap( true );
		textarea.setFont( new Font("Dialog", 2 ,20) );
		container.add( textarea , BorderLayout.CENTER);
		
		panel = new JPanel( );
		panel.setLayout( new GridLayout(1,3) );
		button1 = new JButton( "清除" );
		button2 = new JButton( "显示" );
		button3 = new JButton( "关闭" );
		panel.add( button1 );
		panel.add( button2 );
		panel.add( button3 );
		container.add( panel , BorderLayout.SOUTH);
		
		TextFieldHandler handler = new TextFieldHandler();
		button1.addActionListener( handler );
		button2.addActionListener( handler );
		button3.addActionListener( handler );
		
		setSize( 200, 200 );
		setVisible( true );
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	}
	
	// 内部类实现监听器接口ActionListener
	private class TextFieldHandler implements ActionListener
	{
		public void actionPerformed( ActionEvent event )
		{
			String string = "";
			// 用户按下清除键
			if ( event.getSource() == button1 )
			{
				textfield.setText("");
			}
			
			// 用户按下显示键
			else if ( event.getSource() == button2 )
			{
				string = textfield.getText();
				textarea.setText(string);
			}
			
			// 用户按下关闭键
			else if ( event.getSource() == button3 )
			{
				System.exit(1);
			}
		}
	}
}