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- import java.awt.*;
- import javax.swing.*;
- public class testGraphics extends JFrame
- {
- Graphics gra;
- Image image;
- public testGraphics(){
- super("test Graphics");
- image = createImage(500,500); //创建一幅提供绘制的图片.
- gra = image.getGraphics(); //获得图片绘制对象
- setSize(500,500);
- setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
- setVisible(true);
- }
- public void paint(Graphics g){
- g.setColor(Color.red);
- g.drawString("testGraphics",100,100);
- }
- public static void main(String args[]){
- new testGraphics();
- }
- };
复制代码
Exception in thread "main" java.lang.NullPointerException
at testGraphics.<init>(gra = image.getGraphics())
不明白为何会抛出异常啊,我获得的是一个图片的绘制对象..高手指点指点哦 |
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