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Thinking in Java
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Sliders and progress bars

A slider (which has already been used in SineWave.java) allows the user to input data by moving a point back and forth, which is intuitive in some situations (volume controls, for example). A progress bar displays data in a relative fashion from “full” to “empty” so the user gets a perspective. My favorite example for these is to simply hook the slider to the progress bar so when you move the slider, the progress bar changes accordingly:

//: c14:Progress.java
// Using progress bars and sliders.
// <applet code=Progress width=300 height=200></applet>
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.event.*;
import javax.swing.border.*;
import com.bruceeckel.swing.*;

public class Progress extends JApplet {
  private JProgressBar pb = new JProgressBar();
  private JSlider sb =
    new JSlider(JSlider.HORIZONTAL, 0, 100, 60);
  public void init() {
    Container cp = getContentPane();
    cp.setLayout(new GridLayout(2,1));
    cp.add(pb);
    sb.setValue(0);
    sb.setPaintTicks(true);
    sb.setMajorTickSpacing(20);
    sb.setMinorTickSpacing(5);
    sb.setBorder(new TitledBorder("Slide Me"));
    pb.setModel(sb.getModel()); // Share model
    cp.add(sb);
  }
  public static void main(String[] args) {
    Console.run(new Progress(), 300, 200);
  }
} ///:~


The key to hooking the two components together is in sharing their model, in the line:

pb.setModel(sb.getModel());


Of course, you could also control the two using a listener, but this is more straightforward for simple situations.

The JProgressBar is fairly straightforward, but the JSlider has a lot of options, such as the orientation and major and minor tick marks. Notice how straightforward it is to add a titled border.
Thinking in Java
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   Reproduced courtesy of Bruce Eckel, MindView, Inc. Design by Interspire