Java sound api - Scanning for midi devices

user_202875 0
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I'm working on a java project that receives midi events from midi hardware using the javax.sound.midi library. In the documentation, it says that MidiSystem.getMidiDeviceInfo() returns a list of all connected midi hardware. It works for me, but the problem is, it only works once. It takes a moment the first time to actually scan for the devices, but each time after that it will immediately return that same list even if new devices have been connected. Is there a way to force it to rescan? It will rescan if the application is restarted, but I don't want my users to have to restart if they connect a new midi device.

BTW, I'm using Mac OS X... it's been pointed out that behavior may be different for different OS's.

midi-instrument midi audio java
5 Answers

I answered this is Update list of Midi Devices in Java as well, but for folks who wind up here, there's now a library that supports this correctly: https://github.com/DerekCook/CoreMidi4J

The library acts a device provider for the MIDI Subsystem, so it's basically a drop-in and all your existing code will work.

I am not the author, but it works well for my needs, and it took a fair bit of searching to find, so I'm posting it here for others who encounter the problem.

user_9661040

I found a solution which uses the JavaFX thread. For some reason this works at least on MacOSX. On a normal thread it doesn't work.

import fx.FX_Platform;
import javafx.embed.swing.JFXPanel;
import javax.sound.midi.MidiDevice;
import javax.sound.midi.MidiSystem;


public class miditest {
  
  
  static public void main( String[] args ) {
    // **** Just to init FX platform
    new JFXPanel();    
    new Thread( () -> {
      for( int ix=0; ix<1000; ix++ ) {
        try {
          Thread.sleep(2000);
        } catch( InterruptedException e ) {          
        }
        FX_Platform.runLater( () -> {
          MidiDevice.Info[] infos = MidiSystem.getMidiDeviceInfo();
          System.out.println("FOUND: " + infos.length);
          for( MidiDevice.Info midiinfo : infos ) {
            System.out.println(midiinfo);
          }
        });
      }
    }).start();
    

  }
  
}
user_1971980
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