如何使用JSlider更改JLabel背景颜色

Question

JSlider with "ChangeListener" interface and handle"ChangeEvent" that will change JLabel background color when slider value is change.please help me i couldn't do it. thanks in advance.i couldn't apply JLabel

              package org.kodejava.example.swing;
              import javax.swing.*;
               import javax.swing.event.ChangeEvent;
               import javax.swing.event.ChangeListener;
              import java.awt.*;
           public class JSliderDemo extends JPanel implements ChangeListener {
private JTextField field;

public JSliderDemo() {
    initializeUI();
}

private void initializeUI() {
    setLayout(new BorderLayout());
    setPreferredSize(new Dimension(400, 100));

    //
    // Creates an instance of JSlider with a horizontal
    // orientation. Define 0 as the minimal value and
    // 50 as the maximum value. The initial value is set
    // to 10.
    //
    JSlider slider = new JSlider(JSlider.HORIZONTAL, 0, 50, 10);

    slider.setPaintTicks(true);
    slider.setPaintLabels(true);
    slider.setMinorTickSpacing(1);
    slider.setMajorTickSpacing(10);

    slider.addChangeListener(this);

    JLabel label = new JLabel("The Value:");
    field = new JTextField(5);

    JPanel panel = new JPanel();
    panel.setLayout(new FlowLayout());
    panel.add(label);
    panel.add(field);

    add(slider, BorderLayout.NORTH);
    add(panel, BorderLayout.SOUTH);
}

public void stateChanged(ChangeEvent e) {
    JSlider slider = (JSlider) e.getSource();

    //
    // Get the selection value of JSlider
    //
    field.setText(String.valueOf(slider.getValue()));
}

public static void showFrame() {
    JPanel panel = new JSliderDemo();
    panel.setOpaque(true);

    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setTitle("Slider Example");
    frame.setContentPane(panel);
    frame.pack();
    frame.setVisible(true);
}

public static void main(String[] args) {
    SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            JSliderDemo.showFrame();
        }
    });
}
}

Answer 1

1. JLabel is transparent, then have to change its opacity JLabel.setOpaque(true)

2. read Oracle tutorial How to Use Sliders

Answer 2

JLabel is transparent, cannot change it's background color directly.

you may extend from JLabel and override the paint method

or change the bgcolor of panel. You're putting JLabel on panel and when the slider moves, just change the bgcolor of that panel. Since JLabel is transparent, you will see the change.

As for code try adding something like this inside your statechange method

panel.setBackground(new Color(int,int,int));//ints could be slider.getValue();