Question

我正在尝试逐个向JPanel添加10个按钮，然后将它们全部添加到JFrame。我需要让我的for循环，因为它必须很容易改变按钮的数量。所有按钮也需要有不同的颜色和文本（我知道它们可以使用下面的代码获得相同的颜色，但现在可以了。）

以下代码的输出只是一个包含10个白色按钮且没有文字/颜色的框架。为什么colors，text和actionlistener没有连接到我的按钮？

我已阅读其他问题，我必须小心谨慎处理有关frame.add(panel，frame.pack()和frame.setVisible(true)的展示位置，但我认为这些问题已正确放置在forloop之外1}}。我也尝试使用frame.setContentPane(panel)，但这给出了相同的结果 - 一个框架有10个白色按钮，没有文字/颜色。

CMain class：

public class CMain extends MyButton {
public static void main(String[] args) {

    Random randomGenerator = new Random();
    int numberofbuttons = 10;

    JPanel panel = new JPanel();
    JFrame frame = new JFrame("MyButton testing");

    for (int i = 0; i < numberofbuttons; i++) {

        float r = randomGenerator.nextFloat();float g = randomGenerator.nextFloat();float b = randomGenerator.nextFloat();float r2 = randomGenerator.nextFloat();float g2 = randomGenerator.nextFloat();float b2 = randomGenerator.nextFloat();

        String theText = "SWITCH ME BACK";
        String theOtherText = "button nr: " + i;
        Color theColor = new Color(r, g, b);
        Color theOtherColor = new Color(r2, g2, b2);

        MyButton myb = new MyButton(theColor, theOtherColor, theText, theOtherText);
        panel.add(myb);
    }
    frame.add(panel);
    frame.pack();
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}

MyButton class：

public class MyButton extends JButton implements ActionListener {

private JButton button;
private Color col1;
private Color col2;
private String text1;
private String text2;

public MyButton(Color col1, Color col2, String text1, String text2) {
    this.col1 = col1;
    this.col2 = col2;
    this.text1 = text1;
    this.text2 = text2;
    button = new JButton(text1);
    button.setOpaque(true);
    button.setBackground(col1);
    button.addActionListener(this);
}

public MyButton() {
    this(Color.blue, Color.red, "click = make red", "click = reset to blue");
}

public void ToggleState() {
    Color initialBackground = button.getBackground();

    if (initialBackground == col1) {
        button.setBackground(col2);
        button.setText(text2);
    } else if (initialBackground == col2) {
        button.setBackground(col1);
        button.setText(text1);
    }
}

public void actionPerformed(ActionEvent e) {
    if (e.getSource() == button) {
        this.ToggleState();
    }
}
}

Answer 1

您正在使用您的类创建两个JButton，一个是类本身的对象（如果您愿意，则为this），第二个是类中的button JButton变量：

public class MyButton extends JButton implements ActionListener {  // **** this is a JButton

    private JButton button; // ***** and so is THIS!

删除button变量，仅适用于this，您的问题可能会得到解决。

public class MyButton extends JButton implements ActionListener {  // this is a JButton

    // private JButton button; // get rid of this
    // and then change all code where you try to use button to this.

如，

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

public class MyButton extends JButton implements ActionListener {

    // private JButton button;
    private Color col1;
    private Color col2;
    private String text1;
    private String text2;

    public MyButton(Color col1, Color col2, String text1, String text2) {

        super(text1);   // *********** also add this **********

        this.col1 = col1;
        this.col2 = col2;
        this.text1 = text1;
        this.text2 = text2;
        // button = new JButton(text1);
        this.setOpaque(true);
        this.setBackground(col1);
        this.addActionListener(this);
    }

    public MyButton() {
        this(Color.blue, Color.red, "click = make red", "click = reset to blue");
    }

    public void ToggleState() {
        Color initialBackground = this.getBackground();

        if (initialBackground == col1) {
            this.setBackground(col2);
            this.setText(text2);
        } else if (initialBackground == col2) {
            this.setBackground(col1);
            this.setText(text1);
        }
    }

    public void actionPerformed(ActionEvent e) {
        // if (e.getSource() == button) {
        this.ToggleState();
        // }
    }
}

向JFrame添加多个按钮，文本+颜色不显示

1 个答案: