Is there a way to produce sound with Java?

[Carey Brown]

What is "rsltn" ?

[Kevin Simonson]

Carey Brown wrote:What is an example of command line arguments that you're using?
Edit: sorry I missed your comment at the end.

java Synth 96 6 0 127 6500

[Kevin Simonson]

Carey Brown wrote:What is "rsltn" ?

Resolution. I guess I should have spelled it out.

[Kevin Simonson]

Kevin Simonson wrote:

Carey Brown wrote:What is an example of command line arguments that you're using?
Edit: sorry I missed your comment at the end.

java Synth 96 6 0 127 6500

Although I think what I'm going to go with for my game is probably:

java Synth 96 7 0 127 5500

[Carey Brown]

You might consider dropping the last command line argument and changing your sleep() call to

Thread.sleep( sequencer.getMicrosecondLength() / 1_000 );

[Stephan van Hulst]

Actually, you shouldn't be using Thread.sleep() at all. If you want to block the current thread until the track has finished playing, you should use locks and conditions and add a meta event listener to the sequencer.

[Kevin Simonson]

Stephan van Hulst wrote:Actually, you shouldn't be using Thread.sleep() at all. If you want to block the current thread until the track has finished playing, you should use locks and conditions and add a meta event listener to the sequencer.

Stephan, can you tell me where I can go to find out how to "use locks and conditions" and adding "a meta event listener to the sequencer"? Are those things new to Java 8 or Java 9? I'm mostly familiar with Java 6 and 7, and I don't remember anything about locks, conditions, or meta event listeners.

[Campbell Ritchie]

Threads and locks go back to Java1.0.0. Try the Java™ Tutorials. Don't know about meta‑listeners.

[Stephan van Hulst]

The high-level concurrency library was added in Java 5. The classes I'm referring to specifically are java.util.concurrent.locks.ReentrantLock and java.util.concurrent.locks.Condition. You can create a class that is responsible for playing a sequence and blocking until it's done:

import java.util.concurrent.locks.*;

import javax.sound.midi.*;

final class SequencePlayer {
  
  private static final int MIDI_SYSTEM_RESET_STATUS_CODE = 0xFF;
 
  private final Lock lock = new ReentrantLock();
  private final Condition sequenceFinishedCondition = lock.newCondition();
 
  private final MetaEventListener metaEventListener = this::handleMetaMessage;
 
  private final Sequencer sequencer;
 
  private boolean isWaitingForSequenceToFinish;
 
  SequencePlayer(Sequencer sequencer) {
    if (sequencer == null)
      throw new IllegalArgumentException("The sequencer must not be null.");
 
    this.sequencer = sequencer;
  }
 
  void playSequence(Sequence sequence) throws MidiUnavailableException, InvalidMidiDataException, InterruptedException {
    if (sequence == null)
      throw new IllegalArgumentException("The sequence must not be null.");
    
    lock.lockInterruptibly();

    try {
      sequencer.open();
      try (Sequencer sequencer = this.sequencer) {
        isWaitingForSequenceToFinish = true;
        sequencer.addMetaEventListener(metaEventListener);
        sequencer.setSequence(sequence);
        sequencer.start();

        while(isWaitingForSequenceToFinish)
          sequenceFinishedCondition.await();
      }
 
      finally {
        sequencer.removeMetaEventListener(metaEventListener);
        isWaitingForSequenceToFinish = false;
      }
    }
    
    finally {
      lock.unlock();
    }
  }
  
  void stopWaitingForSequenceToFinish() {
    lock.lock();
    
    try {
      isWaitingForSequenceToFinish = false;
      sequenceFinishedCondition.signal();
    }
    
    finally {
      lock.unlock();
    }
  }
 
  private void handleMetaMessage(MetaMessage message) {
    if (message.getStatus() == MIDI_SYSTEM_RESET_STATUS_CODE)
      stopWaitingForSequenceToFinish();
  }
}

[Stephan van Hulst]

Now, let's say that you expanded your application and you want to start playing your melody in the background when something happens and you want to continue doing things in the mean time, but when the application has finished, you want it to wait until the melody has finished playing. You would then use an ExecutorService to play your melody. Add this method to the SequencePlayer:

void playSequenceInBackground(Sequence sequence, ExecutorService executor) {
  executor.submit(() -> {
    playSequence(sequence);
    return null;
  });
}

As long as the threads in the executor service are not daemons, any melodies that started playing will continue playing when the executor service is shut down. That will give you very gracious termination of your application.

Note that I haven't tested this code or that in the previous post. There may be some mistakes I haven't thought of.