以下是我的源程序
import java.awt.*;
import java.awt.event.*;
public class AddressList extends WindowAdapter implements ActionListener,ItemListener
{
Frame f;
TextField tf1,tf2,tf3,tf4,tf5,tf6,tf7;
Label t1,t2,t3,t4,t5,t6;
List ls1;
Button b1,b2,b3;
private Panel p1;
private Panel p2;
private Panel p3;
private Panel p4;
private Panel p5;
private Panel p6;
private Panel p7;
private Panel p8;
public void display()
{
Frame f = new Frame("AddressList");
f.setSize(400,380);
f.setBackground(Color.lightGray);
f.setLocation(200,200);
f.setLayout(new GridLayout(2,1));
ls1 = new List();
f.add(ls1);
p1 = new Panel();
p1.setLayout(new GridLayout(8,1));
f.add(p1);
TextField tf1 = new TextField("1");
Label t1 = new Label("name");
TextField tf2 = new TextField(" ");
Label t2 = new Label("birthday");
TextField tf3 = new TextField(" ");
Label t3 = new Label("phoneNumber");
TextField tf4 = new TextField(" ");
Label t4 = new Label("homeAddress");
TextField tf5 = new TextField(" ");
Label t5 = new Label("QQ");
TextField tf6 = new TextField(" ");
Label t6 = new Label("email");
TextField tf7 = new TextField(" ");
b1 = new Button("Add");
b1.addActionListener(this);
b2 = new Button("query");
b2.addActionListener(this);
b3 = new Button("delete");
b3.addActionListener(this);
p2 = new Panel();
p2.setLayout(new FlowLayout(FlowLayout.LEFT));
p3 = new Panel();
p3.setLayout(new FlowLayout(FlowLayout.LEFT));
p4 = new Panel();
p4.setLayout(new FlowLayout(FlowLayout.LEFT));
p5 = new Panel();
p5.setLayout(new FlowLayout(FlowLayout.LEFT));
p6 = new Panel();
p6.setLayout(new FlowLayout(FlowLayout.LEFT));
p7 = new Panel();
p7.setLayout(new FlowLayout(FlowLayout.LEFT));
p8 = new Panel();
p8.setLayout(new FlowLayout(FlowLayout.LEFT));
p2.add(tf1);
p2.add(t1);
p2.add(tf2);
p3.add(t2);
p3.add(tf3);
p4.add(t3);
p4.add(tf4);
p5.add(t4);
p5.add(tf5);
p6.add(t5);
p6.add(tf6);
p7.add(t6);
p7.add(tf7);
p8.add(b1);
p8.add(b2);
p8.add(b3);
p1.add(p2);
p1.add(p3);
p1.add(p4);
p1.add(p5);
p1.add(p6);
p1.add(p7);
p1.add(p8);
f.addWindowListener(this);
f.setVisible(true);
}
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource() == b1)
{
String str;
str = tf1.getText() + " " +tf2.getText();//提示此处出错
ls1.add(str);
tf1.setText(""+(Integer.parseInt(tf1.getText())+1));
}
}
public static void main(String [] args)
{
(new AddressList()).display();
}
public void itemStateChanged(ItemEvent e) {
// TODO Auto-generated method stub
}
}
提示在98行有问题,看不懂出错原因,请帮忙解决一下。错误信息:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at AddressList.actionPerformed(AddressList.java:98)
at java.awt.Button.processActionEvent(Unknown Source)
at java.awt.Button.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
import java.awt.*;
import java.awt.event.*;
public class AddressList extends WindowAdapter implements ActionListener,ItemListener
{
Frame f;
TextField tf1,tf2,tf3,tf4,tf5,tf6,tf7;
Label t1,t2,t3,t4,t5,t6;
List ls1;
Button b1,b2,b3;
private Panel p1;
private Panel p2;
private Panel p3;
private Panel p4;
private Panel p5;
private Panel p6;
private Panel p7;
private Panel p8;
public void display()
{
Frame f = new Frame("AddressList");
f.setSize(400,380);
f.setBackground(Color.lightGray);
f.setLocation(200,200);
f.setLayout(new GridLayout(2,1));
ls1 = new List();
f.add(ls1);
p1 = new Panel();
p1.setLayout(new GridLayout(8,1));
f.add(p1);
TextField tf1 = new TextField("1");
Label t1 = new Label("name");
TextField tf2 = new TextField(" ");
Label t2 = new Label("birthday");
TextField tf3 = new TextField(" ");
Label t3 = new Label("phoneNumber");
TextField tf4 = new TextField(" ");
Label t4 = new Label("homeAddress");
TextField tf5 = new TextField(" ");
Label t5 = new Label("QQ");
TextField tf6 = new TextField(" ");
Label t6 = new Label("email");
TextField tf7 = new TextField(" ");
b1 = new Button("Add");
b1.addActionListener(this);
b2 = new Button("query");
b2.addActionListener(this);
b3 = new Button("delete");
b3.addActionListener(this);
p2 = new Panel();
p2.setLayout(new FlowLayout(FlowLayout.LEFT));
p3 = new Panel();
p3.setLayout(new FlowLayout(FlowLayout.LEFT));
p4 = new Panel();
p4.setLayout(new FlowLayout(FlowLayout.LEFT));
p5 = new Panel();
p5.setLayout(new FlowLayout(FlowLayout.LEFT));
p6 = new Panel();
p6.setLayout(new FlowLayout(FlowLayout.LEFT));
p7 = new Panel();
p7.setLayout(new FlowLayout(FlowLayout.LEFT));
p8 = new Panel();
p8.setLayout(new FlowLayout(FlowLayout.LEFT));
p2.add(tf1);
p2.add(t1);
p2.add(tf2);
p3.add(t2);
p3.add(tf3);
p4.add(t3);
p4.add(tf4);
p5.add(t4);
p5.add(tf5);
p6.add(t5);
p6.add(tf6);
p7.add(t6);
p7.add(tf7);
p8.add(b1);
p8.add(b2);
p8.add(b3);
p1.add(p2);
p1.add(p3);
p1.add(p4);
p1.add(p5);
p1.add(p6);
p1.add(p7);
p1.add(p8);
f.addWindowListener(this);
f.setVisible(true);
}
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource() == b1)
{
String str;
str = tf1.getText() + " " +tf2.getText();//提示此处出错
ls1.add(str);
tf1.setText(""+(Integer.parseInt(tf1.getText())+1));
}
}
public static void main(String [] args)
{
(new AddressList()).display();
}
public void itemStateChanged(ItemEvent e) {
// TODO Auto-generated method stub
}
}
提示在98行有问题,看不懂出错原因,请帮忙解决一下。错误信息:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at AddressList.actionPerformed(AddressList.java:98)
at java.awt.Button.processActionEvent(Unknown Source)
at java.awt.Button.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
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import java.awt.event.*;public class AddressList extends WindowAdapter implements ActionListener,
ItemListener {
Frame f; TextField tf1, tf2, tf3, tf4, tf5, tf6, tf7; Label t1, t2, t3, t4, t5, t6; List ls1; Button b1, b2, b3; private Panel p1; private Panel p2; private Panel p3; private Panel p4; private Panel p5; private Panel p6; private Panel p7; private Panel p8; public void display() {
Frame f = new Frame("AddressList");
f.setSize(400, 380);
f.setBackground(Color.lightGray);
f.setLocation(200, 200);
f.setLayout(new GridLayout(2, 1));
ls1 = new List();
f.add(ls1);
p1 = new Panel();
p1.setLayout(new GridLayout(8, 1));
f.add(p1);
tf1 = new TextField("1");
t1 = new Label("name");
tf2 = new TextField(" ");
t2 = new Label("birthday");
tf3 = new TextField(" ");
t3 = new Label("phoneNumber");
tf4 = new TextField(" ");
t4 = new Label("homeAddress");
tf5 = new TextField(" ");
t5 = new Label("QQ");
tf6 = new TextField(" ");
t6 = new Label("email");
tf7 = new TextField(" ");
b1 = new Button("Add");
b1.addActionListener(this);
b2 = new Button("query");
b2.addActionListener(this);
b3 = new Button("delete");
b3.addActionListener(this);
p2 = new Panel();
p2.setLayout(new FlowLayout(FlowLayout.LEFT));
p3 = new Panel();
p3.setLayout(new FlowLayout(FlowLayout.LEFT));
p4 = new Panel();
p4.setLayout(new FlowLayout(FlowLayout.LEFT));
p5 = new Panel();
p5.setLayout(new FlowLayout(FlowLayout.LEFT));
p6 = new Panel();
p6.setLayout(new FlowLayout(FlowLayout.LEFT));
p7 = new Panel();
p7.setLayout(new FlowLayout(FlowLayout.LEFT));
p8 = new Panel();
p8.setLayout(new FlowLayout(FlowLayout.LEFT));
p2.add(tf1);
p2.add(t1);
p2.add(tf2);
p3.add(t2);
p3.add(tf3);
p4.add(t3);
p4.add(tf4);
p5.add(t4);
p5.add(tf5);
p6.add(t5);
p6.add(tf6);
p7.add(t6);
p7.add(tf7);
p8.add(b1);
p8.add(b2);
p8.add(b3);
p1.add(p2);
p1.add(p3);
p1.add(p4);
p1.add(p5);
p1.add(p6);
p1.add(p7);
p1.add(p8);
f.addWindowListener(this);
f.setVisible(true);
} public void windowClosing(WindowEvent e) {
System.exit(0);
} public void actionPerformed(ActionEvent e) {
if (e.getSource() == b1) {
String str;
//System.out.println(tf1.getClass());
//System.out.println(tf2.getText());
str = tf1.getText() + " " + tf2.getText();// 提示此处出错
ls1.add(str);
tf1.setText("" + (Integer.parseInt(tf1.getText()) + 1));
}
} public static void main(String[] args) {
(new AddressList()).display();
} public void itemStateChanged(ItemEvent e) {
// TODO Auto-generated method stub }
}