Can Java Sound be used to control the system volume?

Question

Java Sound offers FloatControl instances for various sound line functionality, and both a MASTER_GAIN & VOLUME control type.

Can these controls be

Answer 1

I am using VOLUME control type. This code works for me for XP and WIN 7, but not for OSX. See my example:

import java.io.IOException;

import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.FloatControl;
import javax.sound.sampled.Line;
import javax.sound.sampled.Mixer;
import javax.swing.JPanel;
import javax.swing.JSlider;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

public class VolumeExample extends JPanel {

/**
 * @return main sound control object
 * @throws Exception for any problem
 */
private FloatControl getVolumeControl() throws Exception {
    try {
        Mixer.Info mixers[] = AudioSystem.getMixerInfo();
        for (Mixer.Info mixerInfo : mixers) {
            Mixer mixer = AudioSystem.getMixer(mixerInfo);
            mixer.open();

            //we check only target type lines, because we are looking for "SPEAKER target port"
            for (Line.Info info : mixer.getTargetLineInfo()) {
                if (info.toString().contains("SPEAKER")) {
                    Line line = mixer.getLine(info);
                    try {
                        line.open();
                    } catch (IllegalArgumentException iae) {}
                    return (FloatControl) line.getControl(FloatControl.Type.VOLUME);
                }
            }
        }
    } catch (Exception ex) {
        System.out.println("problem creating volume control object:"+ex);
        throw ex;
    }
    throw new Exception("unknown problem creating volume control object");
}

   VolumeExample() {
        JSlider slider = new JSlider();
        add(slider);

        //this is for setting the value
        slider.addChangeListener(new ChangeListener() {

            @Override
            public void stateChanged(ChangeEvent e) {
                JSlider src = (JSlider)e.getSource();
                //if (src.getValueIsAdjusting()) return; //optional
                if (src.getValue() % 5 !=0) return;
                float value = src.getValue() / 100.0f;
                try {
                    getVolumeControl().setValue(value);
                    //you can put a click play code here to have nice feedback when moving slider
                } catch (Exception ex) {
                    System.out.println(ex);
                }
            }
        });

        //and this is for getting the value
        try {
            slider.setValue((int) (getVolumeControl().getValue()*100.0f));
        } catch (Exception e) {
            System.out.println(e);
        }
    }
}