example4_18.java

书中的例题

/*本示例说明对话框与窗口传递数据*/
import java.awt.*;
import java.awt.event.*;
// 构造窗体类 
class Win extends Frame  implements ActionListener 
{
	Button btn1=new Button("打开对话框");
	TextArea txt=new TextArea(5,8);
	Win()
	{
		super("对话框与窗体传递消息");
		setBounds(50,50,200,200);
        setVisible(true);
		addWindowListener(new WindowAdapter()
		{
		 public void windowClosing (WindowEvent e)
			{
			 System.exit(0);
			}
		} );
		setLayout(new BorderLayout());
		add(btn1,"North");add(txt,"Center");
		btn1.addActionListener(this);
		validate();
	}
 public void actionPerformed(ActionEvent e)
	{
     //实例化对话框
	   Dia dia=new Dia(this, "传递消息对话框",true);
	   dia.setVisible(true);//由于是有模模式的对话框，这时将产生阻塞，直到对话框关闭。
     //取到对话框传递来的消息，放到文本区中
             txt.append(dia.getMessage());
	}

}
//构造对话框类
class Dia extends Dialog implements ActionListener 
{   TextField txt=new TextField(10);
	//构造有模模式的对话框
	 Dia(Frame f, String s,boolean b)
	{
		 super(f,s,b);
         setSize(300,100);
	 setLayout(new FlowLayout());
		add(txt);
		txt.addActionListener(this) ;
		validate();
	}
 public void actionPerformed(ActionEvent e)
	{
      setVisible(false);
	}
    //把对话框的消息传递出去
	public String getMessage()
	{
     return txt.getText();
	}
}
//主类
public class Example4_18
{
	public static void main(String[] args) 
	{
		new Win();
	}
}