java试用（3）awt,UI

程序 （注意要点： control, layout, 事件处理）

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

public class MyFrame extends Frame{

    private TextField tf;

    public static void main(String args[ ]){
        MyFrame fr = new MyFrame("Hello Out There!");
        fr.InitUI();
    }

    public MyFrame (String str){
        super(str); //调用父类的构造方法
    }

    public void InitUI()
    {
        //Frame
        //setSize(200,200);
        setBackground(Color.red);
        

        //setLayout(null);
        //setLayout(new FlowLayout());
        //setLayout(new BorderLayout());        //BAD
        setLayout(new GridLayout(2,3));        
        //setLayout(new CardLayout());     //crash
        //setLayout(new GridBagLayout());

        //menus
        MenuBar mb = new MenuBar();

        Menu m1 = new Menu("File");
        Menu m2 = new Menu("Edit");
        Menu m3 = new Menu("Help");
        mb.add(m1);
        mb.add(m2);
        mb.setHelpMenu(m3);

        setMenuBar(mb);

        // controls
        Panel pan=new Panel();
        pan.setSize(100,100);
        pan.setBackground(Color.yellow);

        Button b1 = new Button("Button1");
        b1.addActionListener(new ButtonHandler());

        Button b2 = new Button("Button2");
        b2.addActionListener(new ActionListener(){
                public void actionPerformed(ActionEvent e)
                {
                    System.out.println("Action 2 occurred");
                    tf.setText("Action 2 occurred");
                }
            });
        
        tf=new TextField(30);

        // frames
        add(pan);
        add(b1);
        add(b2);
        add(tf);

        pack();

        addMouseMotionListener(new MouseMotionAdapter(){ //匿名类开始
            public void mouseDragged(MouseEvent e){
                String s="Mouse dragging: x="+e.getX()+"Y="+e.getY();
                tf.setText(s); }
        } ); //匿名类结束

        setVisible(true);
    }
}

class ButtonHandler implements ActionListener {
    //实现接口ActionListener才能做事件ActionEvent的处理者
    public void actionPerformed(ActionEvent e)
    //系统产生的ActionEvent事件对象被当作参数传递给该方法
    {
        System.out.println("Action occurred");
    //本接口只有一个方法，因此事件发生时，系统会自动调用本方法，需要做的操作就把代码写在则个方法里。
    }
}

编译运行

 javac MyFrame.java

java MyFrame