java中关于paint()方法的问题

[hellen_99010]

能说下我的paint()方法为什么没有被执行嘛，最好能详细点。paint()方法好像是自动被调用的。我写代码画不出东西来。帮调试下，说明下原因。非常感谢！！！

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

public class TestGraphics1 extends Frame{
	Frame f;
	Button b1;
	Button b2;

	TestGraphics1() {
		b1 = new Button("Draw Line");
		b2 = new Button("Draw circle");
		f = new Frame("Draw Graphics");
		f.setBounds(300,300,500,400);
		f.setVisible(true);
		f.setLayout(new FlowLayout());
		f.add(b1);
		f.add(b2);
		f.addWindowListener(new Monitor());
	}

	public void paint(Graphics g) {	
		Color c = g.getColor();
		g.setColor(Color.RED);
		g.drawLine(10,10,20,30);
		g.setColor(c);	
	}


	
	class Monitor extends WindowAdapter {
		public void windowClosing(WindowEvent e) {
			System.exit(0);
		}
	}


	public static void main(String []args) {
		TestGraphics1 tg = new TestGraphics1();
	}
}

[wd9053]

TestGraphics1中的paint()方法不是f的paint()方法，另外，你画的线会与标题栏重合绝大部分

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

public class TestGraphics1 extends Frame{
    Frame f;
    Button b1;
    Button b2;

    TestGraphics1() {
    		super("Draw Graphics");
        b1 = new Button("Draw Line");
        b2 = new Button("Draw circle");
        setBounds(300,300,500,400);
        setLayout(new FlowLayout());
        add(b1);
        add(b2);
        
        addWindowListener(new Monitor());
        setVisible(true);
        
        //下面的paint()方法是TestGraphics1.this的paint方法，而不是f的
        /*f = new Frame("Draw Graphics");
        f.setBounds(300,300,500,400);
        f.setVisible(true);
        f.setLayout(new FlowLayout());
        f.add(b1);
        f.add(b2);
        f.addWindowListener(new Monitor());*/
    }

    public void paint(Graphics g) {  
        Color c = g.getColor();
        g.setColor(Color.RED);
        g.drawLine(100,100,20,30);
        //g.drawLine(10,10,20,30);坐标与标题栏重合了，如果仔细看的话，还是能在左上方看到一个红点的。。。
        g.setColor(c);    
    }


    
    class Monitor extends WindowAdapter {
        public void windowClosing(WindowEvent e) {
            System.exit(0);
        }
    }


    public static void main(String []args) {
        TestGraphics1 tg = new TestGraphics1();
    }
}

[tcm441224375]

学习,飘过

[hellen_99010]

非常感谢楼上的，还能够对paint()这方法的原理说得详细点嘛，比如它的执行调用过情！

[SeaHome81]

借贵地一用,本人还不能发帖,谢谢

初学java,麻烦各位看下代码,问题出在哪里,实在是找不出来...图就是出不来~

import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
public class test {

public test() {
}
public static class drawcanvas extends Canvas{
int x,y;
public drawcanvas(int x,int y){

this.x=x;
this.y=y;
}
public void paint(Graphics g){
g.setColor(Color.red);
g.drawRect(x,y,10,10);
g.fillRect(x,y,10,10);
}

}

public static void main (String[] args) {
JFrame app = new JFrame();
drawcanvas dc = new drawcanvas(640,400);
app.add(dc);
app.setSize(600,600);
app.setLocation(340,100);
app.setVisible(true);
}


}

[旷逍遥]

[Quote=引用 4 楼 的回复:]
借贵地一用,本人还不能发帖,谢谢

初学java,麻烦各位看下代码,问题出在哪里,实在是找不出来...图就是出不来~

import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
public class test {

public test() {
}
public static cla……
[/Quote]


drawcanvas dc = new drawcanvas(240, 40);
你把这个 X Y 改小点,他的左上角已经不在 窗口中了.你肯定看不到了啊