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.
