Java对ActionEvent的疑惑

Question

this is my first question on this website. I have this problem, in this class I have two buttons with two different functions, one to exit and another to put the first and last name in a text field. I can't get the second ActionEvent to work, please help me, thanks.

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

public class Prueba1 extends JFrame implements ActionListener{
    
    private JLabel nombre, apellidos,respondo;
    private JTextField textfield, textfield1;
    private JButton boton,botonoff;
    
    public Prueba1() {
        setLayout(null);
        
        nombre = new JLabel("Nombre:");
        nombre.setBounds(10, 10, 300, 30);
        add(nombre);
        
        apellidos = new JLabel("Apellidos");
        apellidos.setBounds(10, 40, 300, 30);
        add(apellidos);
        
        textfield = new JTextField();
        textfield.setBounds(100,10,150,20);
        add(textfield);
        
        textfield1 = new JTextField();
        textfield1.setBounds(100,40,150,20);
        add(textfield1);
        
        boton = new JButton("¿Que saldrá?");
        boton.setBounds(10,80,120,30);
        boton.addActionListener(this);
        add(boton);
        
        botonoff = new JButton("Salir");
        botonoff.setBounds(10,120,120,30);
        botonoff.addActionListener(this);
        add(botonoff);
        
        respondo = new JLabel("UwU");
        respondo.setBounds(160,80,300,30);
        add(respondo);
    }
    
    public void actionPerformed(ActionEvent e) {
        
        
        if(e.getSource() == boton) {
            String nombreyapellidos, nombre1, apellidos1;
            nombre1 = textfield.getText();
            apellidos1 = textfield1.getText();
            
            nombreyapellidos = nombre1 + apellidos1;
            
            respondo.setText(nombreyapellidos);
            
        }
        
    
    
    }
    
public void actionPerformed1(ActionEvent e) {
        
        
        if(e.getSource() == botonoff) {
            System.exit(0);
            
            
        }
    
    }
    
    public static void main(String args[]) {
        
        Prueba1 clase = new Prueba1();
        clase.setVisible(true);
        clase.setBounds(0, 0, 500, 500);
        clase.setResizable(true);
        clase.setLocationRelativeTo(null);
    }
    
}

Answer 1

When you provide an ActionListener object to a buttons button.addActionListener(listener)

You have several ways to accomplish this.

 button.addActionListener(this);

Is only one way. This way says the the class implements ActionListener. In effect it implements the

public void actionPerformed(ActionEvent e)

method.

Your

public void actionPerformed1(ActionEvent e)

can't be used by the button at all.

Fortunately there are many other ways to describe the code that should be executed when an action event is produced.

An inner class, static or not. Other class/object. A lambda expression.

You can find how to express a lambda here .

Answer 2

Remove public void actionPerformed1(ActionEvent e) method and add the body of that method in the else branch in the body of public void actionPerformed(ActionEvent e) .

  public void actionPerformed(ActionEvent e) {

    if (e.getSource() == boton) {
      String nombreyapellidos, nombre1, apellidos1;
      nombre1 = textfield.getText();
      apellidos1 = textfield1.getText();

      nombreyapellidos = nombre1 + apellidos1;

      respondo.setText(nombreyapellidos);

    } else if (e.getSource() == botonoff) {
      System.exit(0);
    }

  }