JAVA 事件監聽器/事件

事件:MouseEvent/ KeyEvent等等.

對於一個frame要addMouseListener( 你定義的監聽事件)

例如:

class Monitor extends MouseAdapter.. 再實現對應的操作. 查API文檔

在對應的frame類中,

定義paint.. paint的作用就是繪製. 自動繪製, 當視窗被覆蓋等等..時候再出現時候會重繪製

paint會一直被調用的, 甚至是點擊滑鼠等

 

可以把graphics 看做是一支畫筆, 畫筆所使用的地方就是你當前this的對象..

repaint的作用, 強制視窗重繪. 首先調用repaint—> update[實現雙緩衝]—> paint..

 

                         

 

事件來源windows/frame/panel ect...,

監聽器Listener,

處罰事件*Event.

畫筆: graphics

 

 

import java.awt.*;
import java.awt.event.*;
import java.util.Collection.*;
import java.util.*;

public class test{
        public static void main(String args[]){
                new PaintFrame("My PaintBoader");
            }
    }
class PaintFrame extends Frame{
    ArrayList points = null;
    PaintFrame(String s){
        super(s);
        points = new ArrayList();
        setLayout(null);
        setBounds(300, 300,400,300);
        this.setBackground(new Color(204,204,255));
        setVisible(true);
        this.addMouseListener(new Monitor());
    }
    public void paint(Graphics g){
        Iterator i = points.iterator();
        while( i.hasNext() ){
            Point p = (Point)i.next();
            g.setColor(Color.blue);
            g.fillOval(p.x, p.y, 10, 10);
        }
    }
    public void addPoint( Point p ){
        points.add(p);
    }
}
class Monitor extends MouseAdapter{
        public void mousePressed( MouseEvent me ){
                PaintFrame pframe = (PaintFrame)me.getSource();
                pframe.addPoint(new Point(me.getX(), me.getY()));
                pframe.repaint();
            }
    }