求助问题:Exception in thread "main" java.lang.NullPointerException

来源：百度知道 编辑：UC知道 时间：2024/06/14 02:42:51
错误问题:
Exception in thread "main" java.lang.NullPointerException
at awt.GridLayoutTest.main(GridLayoutTest.java:39)
程序如下:
package awt;

import java.awt.Button;
import java.awt.Color;
import java.awt.Frame;
import java.awt.GridLayout;
import java.awt.Panel;
import java.awt.TextField;

public class GridLayoutTest {

public static void main(String[] args) {
Frame frame = null;
Panel pm = null;
Panel pc = null;
Panel ps = null;
String[] s = {"7","8","9","/",
"sprt","4","5","6",
"*","%","1","2",
"3","-","1/x","0",
"+/-",".","+","="};
String[] m = {"MC","MR","MS","M+"};
String[] c = {"Bac

你的程序里Panel ps=null,没有给它赋值，应该是Panel ps=new Panel();

而且你的其余两个Panel都没有赋值，都应该像ps一样赋值为：
Panel pm =new Panel();
Panel pc = new Panel();
Panel ps = new Panel();
没有给他们赋值，却调用他们的方法，肯定会产生NullPointerException异常。
如果还有问题再拿来看。