import java.awt.*;
import java.awt.event.*;public class T extends Frame {
Panel pl; public T() {
super("T"); pl = new Panel(); add(pl); Graphics g = pl.getGraphics();
g.drawRect(0, 0, 30, 40);
}
public static void main(String[] args)
{
Frame f = new T();
f.setSize(800, 600);
f.setVisible(true);
}
}
以上代码问什么会出现异常?请各位高手指点
import java.awt.event.*;public class T extends Frame {
Panel pl; public T() {
super("T"); pl = new Panel(); add(pl); Graphics g = pl.getGraphics();
g.drawRect(0, 0, 30, 40);
}
public static void main(String[] args)
{
Frame f = new T();
f.setSize(800, 600);
f.setVisible(true);
}
}
以上代码问什么会出现异常?请各位高手指点
import java.awt.Graphics;public class T extends Frame {
public T() {
super("T");
}
public void paint(Graphics g) {
g.drawRect(0, 0, 30, 40);
}public static void main(String[] args)
{
Frame f = new T();
f.setSize(800, 600);
f.setVisible(true);
}
}