Learning Java, 4th Edition

Scrollbars and Sliders

JScrollPane is such a handy component that you may not ever need to use scrollbars by themselves. In fact, if you ever do find yourself using a scrollbar by itself, chances are that you really want to use another component called a slider.

There’s not much point in describing the appearance and functionality of scrollbars and sliders. Instead, let’s jump right in with an example that includes both components. Figure 17-12 shows a simple example with both a scrollbar and a slider.

Figure 17-12. Using a scrollbar and a slider

Here is the source code for this example:

    //file: Slippery.java
    import java.awt.*;
    import java.awt.event.*;
    import javax.swing.*;
    import javax.swing.event.*;

    public class Slippery {
      public static void main(String[] args)
      {
        JFrame frame = new JFrame("Slippery v1.0");
        Container content = frame.getContentPane();  // unnecessary  in 5.0+

        JPanel main = new JPanel(new GridLayout(2, 1));
        JPanel scrollBarPanel = new JPanel();
        final JScrollBar scrollBar =
            new JScrollBar(JScrollBar.HORIZONTAL, 0, 48, 0, 255);
        int height = scrollBar.getPreferredSize().height;
        scrollBar.setPreferredSize(new Dimension(175, height));
        scrollBarPanel.add(scrollBar);
        main.add(scrollBarPanel);

        JPanel sliderPanel = new JPanel();
        final JSlider slider =
            new JSlider(JSlider.HORIZONTAL, 0, 255, 128);
        slider.setMajorTickSpacing(48);
        slider.setMinorTickSpacing(16);
        slider.setPaintTicks ...