Question

我已经用Java创建了简单的GUI来测试单击按钮的工作。但是当我按下按钮时，按钮不起作用。

import javax.swing.*;
import java.awt.event.*;
import java.util.*;

public class rigotechnology implements ActionListener{
    JFrame test;
    JButton Try;

    public void main(){
       JFrame test = new JFrame("TEST FILE");
       test.setLayout(null);
       JButton Try = new JButton("TRY");
       Try.setBounds(50,50,80,80);
       test.add(Try);
       test.setSize(200,200);
       test.setVisible(true);
       Try.addActionListener(this);
    }

    public void actionPerformed(ActionEvent e){
       if(e.getSource()==Try){
          JOptionPane.showMessageDialog(test,"hello");
       }
    }

   public static void main(String args[]){
        rigotechnology o = new rigotechnology();
        o.main();
     }
}

Answer 1

在方法main（）中，您重新定义了本地JButton Try，因此try in actionPerformed始终为null。

public void main(){
   test = new JFrame("TEST FILE");
   test.setLayout(null);
   Try = new JButton("TRY");
   Try.setBounds(50,50,80,80);
   test.add(Try);
   test.setSize(200,200);
   test.setVisible(true);
   Try.addActionListener(this);
}

当我按下按钮时，按钮不起作用？

1 个答案: