textfieldtest.java

这是清华大学编写的JAVA教材中所有题目的源代码！

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

class TextFieldTest extends Frame implements TextListener,ActionListener
{
	Label lbl=new Label();
	TextField tf=new TextField("",20);

	public TextFieldTest(String title) 
	{
		super(title);

		tf.setEchoChar('#');
		tf.addActionListener(this);
		tf.addTextListener(this);
		tf.addKeyListener(new KeyAdapter()
		{
			public void keyTyped(KeyEvent e)
			{
				char ch=e.getKeyChar();
				if(ch<'0'||ch>'9')
					e.consume();
			}
		});
		
		add(tf,BorderLayout.NORTH);
		add(lbl,BorderLayout.SOUTH);
		setSize(300,200);
		setVisible(true);		
	}
	
	public void textValueChanged(TextEvent e)
	{
		lbl.setText(tf.getText());
	}
	
	public void actionPerformed(ActionEvent e)
	{
		tf.setText("");
	}

	public static void main(String args[])
	{
		new TextFieldTest("文本域示例");
	}
}