/**
* @(#)ReaderAdd.java
*
*
* @author Administrator
* @version 1.00 2008/1/5
*/
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import java.sql.*; public class readeradd extends JFrame implements ActionListener{
private JButton rad_add1,rad_clear1;
private JLabel readname1,borrowcard1;
private JTextField readnametext1,borrotcardtext1;
private JFrame frame2;
public void actionPerformed(ActionEvent e){}
public readeradd() {
JFrame.setDefaultLookAndFeelDecorated(true);
frame2=new JFrame("读者添加");
frame2.setLayout(new GridLayout(3,2,20,20));
rad_add1=new JButton("添加");
rad_clear1=new JButton("取消");
readname1=new JLabel("读者姓名");
borrowcard1=new JLabel("借书证号");
readnametext1=new JTextField();
readnametext1=new JTextField();
frame2.add(readname1);
frame2.add(readnametext1);
frame2.add(borrowcard1);
frame2.add(borrotcardtext1);
frame2.add(rad_add1);
frame2.add(rad_clear1);
rad_add1.addActionListener(this);
rad_clear1.addActionListener(this);
frame2.pack();
frame2.setLocationRelativeTo(null);
frame2.setSize(200,150);
frame2.setVisible(true);
}
public static void main(String[]args)
{
new readeradd();
}
}错误提示如下:Exception in thread "main" java.lang.NullPointerException
at java.awt.Container.addImpl(Container.java:1015)
at java.awt.Container.add(Container.java:928)
at javax.swing.JFrame.addImpl(JFrame.java:479)
at java.awt.Container.add(Container.java:351)
at readeradd.<init>(readeradd.java:38)
at readeradd.main(readeradd.java:53)盯了一天屏幕了,有点晕了,路过帮忙看看……
* @(#)ReaderAdd.java
*
*
* @author Administrator
* @version 1.00 2008/1/5
*/
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import java.sql.*; public class readeradd extends JFrame implements ActionListener{
private JButton rad_add1,rad_clear1;
private JLabel readname1,borrowcard1;
private JTextField readnametext1,borrotcardtext1;
private JFrame frame2;
public void actionPerformed(ActionEvent e){}
public readeradd() {
JFrame.setDefaultLookAndFeelDecorated(true);
frame2=new JFrame("读者添加");
frame2.setLayout(new GridLayout(3,2,20,20));
rad_add1=new JButton("添加");
rad_clear1=new JButton("取消");
readname1=new JLabel("读者姓名");
borrowcard1=new JLabel("借书证号");
readnametext1=new JTextField();
readnametext1=new JTextField();
frame2.add(readname1);
frame2.add(readnametext1);
frame2.add(borrowcard1);
frame2.add(borrotcardtext1);
frame2.add(rad_add1);
frame2.add(rad_clear1);
rad_add1.addActionListener(this);
rad_clear1.addActionListener(this);
frame2.pack();
frame2.setLocationRelativeTo(null);
frame2.setSize(200,150);
frame2.setVisible(true);
}
public static void main(String[]args)
{
new readeradd();
}
}错误提示如下:Exception in thread "main" java.lang.NullPointerException
at java.awt.Container.addImpl(Container.java:1015)
at java.awt.Container.add(Container.java:928)
at javax.swing.JFrame.addImpl(JFrame.java:479)
at java.awt.Container.add(Container.java:351)
at readeradd.<init>(readeradd.java:38)
at readeradd.main(readeradd.java:53)盯了一天屏幕了,有点晕了,路过帮忙看看……
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是不是这句有问题?
你 extends 干什么又new一个
readnametext1=new JTextField();写了2次
代码应该是复制的吧?看看你自己的代码,是不是这里错了
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import java.sql.*; public class readeradd implements ActionListener{
private JButton rad_add1,rad_clear1;
private JLabel readname1,borrowcard1;
private JTextField readnametext1,borrotcardtext1;
private JFrame frame2;
public void actionPerformed(ActionEvent e){}
public readeradd() {
frame2=new JFrame("读者添加");
frame2.setLayout(new GridLayout(3,2,20,20));
rad_add1=new JButton("添加");
rad_clear1=new JButton("取消");
readname1=new JLabel("读者姓名");
borrowcard1=new JLabel("借书证号");
readnametext1=new JTextField();
borrotcardtext1=new JTextField();
Container c = frame2.getContentPane();
c.add(readname1);
c.add(readnametext1);
c.add(borrowcard1);
c.add(borrotcardtext1);
c.add(rad_add1);
c.add(rad_clear1);
rad_add1.addActionListener(this);
rad_clear1.addActionListener(this);
frame2.pack();
frame2.setLocationRelativeTo(null);
frame2.setSize(200,150);
frame2.setVisible(true);
frame2.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[]args)
{
new readeradd();
}
}你漏写了一个borrotcardtext1=new JTextField();