2D图形画不出来

[乾K大挪移]

import java.awt.*;
import java.awt.geom.Rectangle2D;
import javax.swing.*;

public class DrawTest
{
	public static void main(String[] args)
	{
		DrawFrame frame=new DrawFrame();
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setVisible(true);
	}
}

class DrawFrame extends JFrame
{
	public DrawFrame()
	{
		setSize(Width,Height);
		setTitle("DrawTest");
		setLocation(500, 300);
		
		DrawPanel panel=new DrawPanel();
		add(panel);
	}
	
	public static final int Width=400;
	public static final int Height=500;

}

class DrawPanel extends JPanel
{
	public void paintComponet(Graphics g)
	{

		super.paintComponent(g);
		Graphics2D g2=(Graphics2D)g;
		
		//画一个方块
		Rectangle2D rect=new Rectangle2D.Double(100,100,200,150);
		g2.draw(rect);
	}
}

为什么我的rect画不出来？？？

[乾K大挪移]

我知道是这本书的，但是为什么出不来？？？
我代码哪里写错了？
我对照了半天没找出不一样的地方

[witcheryne]

绘图操作 必须在 Component 的 paint(Graphics g) 方法内进行...
当产生重绘情况的时候 系统将自动调用paint()方法对容器进行重绘

把把你的代码修改了一下...

import java.awt.*;
import java.awt.geom.Rectangle2D;
import javax.swing.*;

public class DrawTest
{
    public static void main(String[] args)
    {
        DrawFrame frame=new DrawFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
}

class DrawFrame extends JFrame
{
    public DrawFrame()
    {
        setSize(Width,Height);
        setTitle("DrawTest");
        setLocation(500, 300);
        
        DrawPanel panel=new DrawPanel();
        this.add(panel, java.awt.BorderLayout.CENTER);//使用了布局管理器    }
    
    public static final int Width=400;
    public static final int Height=500;

}

class DrawPanel extends JPanel
{
    //绘图必须在这里进行
    public void paint(Graphics g) 
    {
	paintComponet(g);
    }
	
    public void paintComponet(Graphics g)
    {

        super.paintComponent(g);
        Graphics2D g2=(Graphics2D)g;
        
        //画一个方块
        Rectangle2D rect=new Rectangle2D.Double(100,100,200,150);
        g2.draw(rect);
    }
}

[witcheryne]

晕~~ 代码中加不成颜色 - -|
"[color=#FF0000] "没有这句 代码...

[乾K大挪移]

楼上的说的很有道理！！！谢了！

[乾K大挪移]

只显示一个空白的Frame，里面什么也没有。

[xray2005]

这个是《Java核心技术第一卷，基础知识》书上的例子，我昨天刚看完这章哦。我的按照书上的代码敲，都可以画出来啊。我还加其颜色，写字等等。
代码和你一样呢！
import java.awt.*;
import java.awt.color.*;
import java.awt.geom.*;
import java.awt.geom.Ellipse2D.Double;
import java.awt.font.*;
import javax.swing.*;

class DrawPanel extends JPanel {
public void paintComponent(Graphics g) {

super.paintComponent(g);
// this.setBackground(Color.RED);

Graphics2D g2 = (Graphics2D) g;
double leftx = 100;
double topy = 100;
double width = 200;
double height = 150;
Rectangle2D rect = new Rectangle2D.Double(leftx, topy, width, height);
// g2.setColor(Color.red);
g2.draw(rect);
Ellipse2D ellipse = new Ellipse2D.Double();
ellipse.setFrame(rect);
g2.draw(ellipse);
g2.draw(new Line2D.Double(leftx, topy, width + leftx, height + topy));
double ceterX = rect.getCenterX();
double ceterY = rect.getCenterY();
double radius = 150;
Ellipse2D circle = new Ellipse2D.Double();
circle.setFrameFromCenter(ceterX, ceterY, ceterX + radius, radius
+ ceterY);
g2.setColor(Color.blue);
g2.draw(circle);
// g2.setPaint(Color.RED);
String message = "老婆，我爱你！";
Font sansbold114 = new Font("SansSerif", Font.BOLD, 14);
g2.setFont(sansbold114);
FontRenderContext context = g2.getFontRenderContext();
Rectangle2D bouds = sansbold114.getStringBounds(message, context);
double x = (getWidth() - bouds.getWidth()) / 2;
double y = (getHeight() - bouds.getHeight()) / 2;
double ascent = -bouds.getY();
double baseY = y + ascent;
g2.drawString(message, (int) x, (int) baseY);
// g2.fill(circle);
g2.dispose();
}
}

class DrawFrame extends JFrame {
public static final int DEFAULT_WIDTH = 400;
public static final int DEFALT_HEGIHT = 400;

public DrawFrame() {
this.setTitle("DrawTest");
this.setSize(DEFAULT_WIDTH, DEFALT_HEGIHT);

DrawPanel panel = new DrawPanel();
this.add(panel);
}

}

public class DrawTest {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
DrawFrame frame = new DrawFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}

}

[magichao4141]

呵呵~ 我也正在看这本书