Question

java 用绘图画不出图

RT 请高手门看下吧，照书上打的就是出不来 纠结死了

import java.awt.*;
import javax.swing.*;
public class DrawingTest {
public static void main(String[] args) {
JFrame jf;
Container contentPane;
Graphics g;
jf = new JFrame("My First Rectangle");
jf.setSize(500,500);
jf.setLocation(100,100);
jf.setVisible(true);
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

contentPane = jf.getContentPane();
g = contentPane.getGraphics();
g.setColor(Color.BLUE);
g.fillRect(150, 150, 100, 30);
}

}

Answer 1

你的用法有误，应该如下
import java.awt.Color;
import java.awt.Container;
import java.awt.Graphics;

import javax.swing.JFrame;

public class DrawingTest {
public static void main(String[] args) {
JFrame jf;
Container contentPane;
Graphics g;
jf = new JFrame("My First Rectangle") {

@Override
public void paint(Graphics g) {
g.setColor(Color.BLUE);
g.fillRect(150, 150, 100, 30);
}

};
jf.setSize(500,500);
jf.setLocation(100,100);
jf.setVisible(true);
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

}

}

Answer 2

需要用小程序APPLET来写，重写draw函数~

Answer 3

有异常吗？
把jf.setVisible(true);移到最后一句代码试试？