我这是什么地方不正确呀?是不是Path设置的不全啊?

[petty108]

F:\java\l1>java Exam1_4 23 432
Exception in thread "main" java.lang.NullPointerException
at java.awt.Container.addImpl(Container.java:621)
at java.awt.Container.add(Container.java:307)
at ApplicationFrame.<init>(Exam1_4.java:27)
at Exam1_4.main(Exam1_4.java:8)

[chyvlcy123]

空异常 代码帖上来啊

[petty108]

import java.awt.*;
import java.awt.event.*;
public class Exam1_4
{
public static void main(String args[])
{
ApplicationFrame AF=new ApplicationFrame();
}
}
class ApplicationFrame extends Frame implements ActionListener
{
Label prompt;
TextField text1,text2;
Button btn;
int a=0,b=0;
public ApplicationFrame()
{
super("我的窗口");
prompt=new Label("请输入两个整型数：");
text1=new TextField(4);
text1=new TextField(4);
btn=new Button("计算");
setLayout(new FlowLayout());
add(prompt);
add(text1);
add(text2);
add(btn);
btn.addActionListener(this);
show();
}
public void actionPerformed(ActionEvent e)
{
a=Integer.parseInt(text1.getText());
b=Integer.parseInt(text2.getText());
}
public void paint(Graphics g)
{
g.drawString("运行结果："+a+"*"+b+"="+a*b,20,80);
}
}

[liky5387]

LZ：你的text2都没有初始化，它当然会抛NullPointerException了．

text2=new TextField(4);

[xiaxinhuo]

text1=new TextField(4);
text1=new TextField(4);
btn=new Button("计算");
好象有点问题,text1和text2吧

[petty108]

谢谢!!
真是太太了我!
哈哈!!
谢谢

[MySoftZone]

单步调试一下不就出来了