Question

带有“ChangeListener”接口的JSlider并处理“ChangeEvent”，当滑块值发生变化时，它将改变JLabel背景颜色。请帮助我，我无法做到。提前谢谢。我无法申请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

JLabel是透明的，然后必须更改其不透明度JLabel.setOpaque(true)
阅读Oracle教程How to Use Sliders

Answer 2

JLabel是透明的，不能直接改变它的背景颜色。

您可以从JLabel扩展并覆盖绘制方法

或更改面板的bgcolor。您将JLabel放在面板上，当滑块移动时，只需更改该面板的bgcolor即可。由于JLabel是透明的，您将看到更改。

至于代码，请尝试在statechange方法中添加类似的内容

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

如何使用JSlider更改JLabel背景颜色

2 个答案: