大家好,我刚学Java不久,在设计一个可以在窗口标题上显示鼠标位置的Frame时,却怎么也显示不了,不知道问题在哪里。
import java.awt.*;
import java.awt.event.*;
public class homework7th_2 extends Frame{
Label mouseInfo1;
public homework7th_2(){
mouseInfo1=new Label(""); addMouseMotionListener(new MouseMotionAdapter(){
public void mouseMoved(MouseEvent e){
mouseInfo1.setText(e.getX()+" "+e.getY());
}
});
setTitle(mouseInfo1.getText());//这里明明设置了标题,但就是没显示,不知道怎么回事
setSize(200,200);
setVisible(true);
}
public static void main(String[] args){
new homework7th_2();
}}
如果在窗体里显示就可以,但在标题上就无法显示
import java.awt.*;
import java.awt.event.*;
public class homework7th_2 extends Frame{
Label mouseInfo1;
public homework7th_2(){
mouseInfo1=new Label(""); addMouseMotionListener(new MouseMotionAdapter(){
public void mouseMoved(MouseEvent e){
mouseInfo1.setText(e.getX()+" "+e.getY());
}
});
setTitle(mouseInfo1.getText());//这里明明设置了标题,但就是没显示,不知道怎么回事
setSize(200,200);
setVisible(true);
}
public static void main(String[] args){
new homework7th_2();
}}
如果在窗体里显示就可以,但在标题上就无法显示
楼主【Jo_Cai】截止到2008-06-24 15:25:00的历史汇总数据(不包括此帖):
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结贴率:75.00 % 结分率:75.00 %
楼主加油
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import javax.swing.JFrame;
public class Homework7th_2 extends JFrame {
public Homework7th_2() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
addMouseMotionListener(new MouseMotionAdapter(){
public void mouseMoved(MouseEvent e) {
setTitle(e.getX() + " " + e.getY());
}
});
setSize(200, 200);
setVisible(true);
} public static void main(String[] args) {
new Homework7th_2();
}}
照您那么说有错误出现:java.lang.NullPointerException
at homework7th_2.<init>(homework7th_2.java:17)
at homework7th_2.main(homework7th_2.java:22)
你用的方法错了吧,我帮你改成这样了.你试试import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import javax.swing.JFrame;
public class Homework7th_2 extends JFrame {
public Homework7th_2() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
addMouseMotionListener(new MouseMotionAdapter(){
public void mouseMoved(MouseEvent e) {
setTitle(e.getX() + " " + e.getY());
}
});
setSize(200, 200);
setVisible(true);
} public static void main(String[] args) {
new Homework7th_2();
} }