Question

我无法找到一种方法来调用动作侦听器，该侦听器返回在底部文本区域中单击的按钮的值。

我使用for循环创建了按钮，并没有明确地给按钮命名，所以我不知道在尝试合并ActionListener时如何引用它们。

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class buttoner implements ActionListener {
//JFrame
JFrame frame = new JFrame("Button Game");

//Make JPanels
JPanel panelLabel = new JPanel();
JPanel buttonGrid = new JPanel(new GridLayout(0,10));
JPanel bottomPanel = new JPanel();

//JLabel
private JLabel label1 = new JLabel("The Button Game");

public buttoner() {
    //set layout
    frame.setLayout(new BorderLayout());
    frame.add(panelLabel, BorderLayout.NORTH);
    frame.add(buttonGrid, BorderLayout.CENTER);
    frame.add(bottomPanel, BorderLayout.SOUTH);
    //Set stuff
    frame.setLocationRelativeTo(null);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(500,700);
    frame.setVisible(true);
    //Change label color
    label1.setForeground(Color.RED);
    //add Label
    panelLabel.add(label1);
    //add Buttons
    for (int i = 1; i <= 60; i++) {
        String val = Integer.toString(i);
        buttonGrid.add(new JButton(val));
    }
    //Add JText Area to bottom JPanel
    String num = "value";
    JTextArea jta = new JTextArea(num, 1, 1);
    bottomPanel.add(jta);
    frame.pack();
}

public static void main(String args[]){
    buttoner gui = new buttoner();
}

public void actionPerformed(ActionEvent a) {

}
}

Answer 1

我创建了一个动作侦听器，将值放在GUI底部的文本区域中。

我修复了你的代码的一些问题。

在main方法中，我调用了SwingUtilities invokeLater方法将Swing GUI放在Event Dispatch thread（EDT）上。必须在EDT上创建和更新Swing组件。
Java类的名称必须以大写字母开头。
将Swing组件放在JPanel上会更安全，而不是直接将它们添加到JFrame中。
我将创建JFrame的代码与创建JPanels的代码分开。您的代码的任何读者（包括您自己）都应该更容易理解正在发生的事情。
在createMainPanel方法中，我对代码进行了分组，以便将与buttonGrid JPanel有关的所有内容放在代码中的一个位置。
我将动作侦听器添加到创建buttonGrid JPanel的代码中。
我编写了动作侦听器代码，用左键单击按钮标签更新JTextArea。

这是更正后的代码。

package com.ggl.testing;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;

public class Buttoner implements ActionListener {
    // JFrame
    private JFrame frame = new JFrame("Button Game");

    // Make JPanels
    private JPanel panelLabel = new JPanel();
    private JPanel buttonGrid = new JPanel(new GridLayout(0, 10));
    private JPanel bottomPanel = new JPanel();

    // JLabel
    private JLabel label1 = new JLabel("The Button Game");

    private JTextArea jta;

    public Buttoner() {
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(createMainPanel());
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    private JPanel createMainPanel() {
        JPanel panel = new JPanel();
        panel.setLayout(new BorderLayout());

        // Change label color
        label1.setForeground(Color.RED);
        // add Label
        panelLabel.add(label1);
        panel.add(panelLabel, BorderLayout.NORTH);

        // add Buttons
        for (int i = 1; i <= 60; i++) {
            String val = Integer.toString(i);
            JButton button = new JButton(val);
            button.addActionListener(this);
            buttonGrid.add(button);
        }
        panel.add(buttonGrid, BorderLayout.CENTER);

        // Add JText Area to bottom JPanel
        String num = "value";
        jta = new JTextArea(num, 1, 1);
        jta.setEditable(false);
        bottomPanel.add(jta);
        panel.add(bottomPanel, BorderLayout.SOUTH);

        return panel;
    }

    public static void main(String args[]) {
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                new Buttoner();
            }
        };
        SwingUtilities.invokeLater(runnable);
    }

    public void actionPerformed(ActionEvent a) {
        JButton button = (JButton) a.getSource();
        jta.setText(button.getText());
    }
}

Answer 2

尝试创建一个按钮数组，并将新创建的按钮添加到数组中。见评论。

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class buttoner implements ActionListener {
//JFrame
JFrame frame = new JFrame("Button Game");

//Make JPanels
JPanel panelLabel = new JPanel();
JPanel buttonGrid = new JPanel(new GridLayout(0,10));
JPanel bottomPanel = new JPanel();

//JLabel
private JLabel label1 = new JLabel("The Button Game");
private JButton buttons[] = new JButton[60]; //create an array of button for future reference

public buttoner() {
    //set layout
    frame.setLayout(new BorderLayout());
    frame.add(panelLabel, BorderLayout.NORTH);
    frame.add(buttonGrid, BorderLayout.CENTER);
    frame.add(bottomPanel, BorderLayout.SOUTH);
    //Set stuff
    frame.setLocationRelativeTo(null);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(500,700);
    frame.setVisible(true);
    //Change label color
    label1.setForeground(Color.RED);
    //add Label
    panelLabel.add(label1);
    //add Buttons
    for (int i = 1; i <= 60; i++) {
        String val = Integer.toString(i);
        JButton btn = new JButton(val);
        btn.addActionListener(this); //add an actionListener right away
        buttons[i] = btn; //add the button in the array for future reference
        buttonGrid.add(btn);
    }
    //Add JText Area to bottom JPanel
    String num = "value";
    JTextArea jta = new JTextArea(num, 1, 1);
    bottomPanel.add(jta);
    frame.pack();
}

public static void main(String args[]){
    buttoner gui = new buttoner();
}

public void actionPerformed(ActionEvent a) {

}
}

向循环创建的JButtons添加动作侦听器

2 个答案: