Java Sound refresh Lines list after attaching a microphone

Question

I have a simple capture/playback Swing app that has to detect if there is no appropriate microphone attached to the computer and warn the user. After a lot of fiddling aroun

Answer 1

Using the original post as inspiration, I came up with this as a means to detect when a mic is lost or gained. It detects (on my system) when a USB mic is plugged in or unplugged. I'm calling it from a background thread loop. The original method did not work for me as there is a built-in mic on the laptop, so I needed to detect the addition of second mic.

...
//call this once somewhere to turn the caching period down for faster detection
    try
    {
        //try to set the caching period, defaults to something like 55 seconds
        com.sun.media.sound.JDK13Services.setCachingPeriod(5);
    }
    catch( Exception e)
    {
        System.err.println("exception attempting to call com.sun.media.sound.JDK13Services.setCachingPeriod->" + e);
    }
...

private int lastNumMics = -1;
private synchronized void micCheck()
{
    Line.Info[] lineInfoArray = AudioSystem.getSourceLineInfo(Port.Info.MICROPHONE);
    int numMics = lineInfoArray == null ? 0 : lineInfoArray.length;
    if( lastNumMics > -1 )
    {
        if( numMics < lastNumMics )
        {
            //MICROPHONE_LOST
        }
        else if( numMics > lastNumMics )
        {
            //MICROPHONE_GAINED
        }
    }
    lastNumMics = numMics;
}