检测USB状态更改Android Java

Question

I want to be able to trigger an event when a user connects or disconnects a USB device. I have the following code:

public static boolean isConnected(Context context) {
    Intent intent = context.registerReceiver(null, new IntentFilter("android.hardware.usb.action.USB_STATE"));
    return intent.getExtras().getBoolean("connected");
}

The above is from another StackOverflow question.

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How can I go about the problem I'm facing? I don't think it would be practical to check every x second if the state has changed. So, I checked online for an event listener about USB_CONNECTION, but I can't seem to find any. Actually, I did find a few but they were confusing and quite old. (A year or two ago.)

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TRIED CODE

while(notFinished) {
    if (!isConnected(this)) {
        pause();
    } else if (!mediaPlayer.isPlaying() && isConnected(this)) {
        play();
    } else {
        Log.e("[ERROR]: ", "An error has occured at startSong!");
    }
    try {
        Thread.sleep(100);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
}

^^^ Clearly not efficient, but it does work (somewhat). So, that's why I came over here to know if there was a listener for USB_CONNECTION_STATUS. I think this would be a lot faster.

Answer 1

You can use BroadcastReceiver for receiving connected and disconnected actions:

        BroadcastReceiver receiver = new BroadcastReceiver() {

            @Override
            public void onReceive(Context context, Intent intent) {
                if (intent.getExtras().getBoolean("connected")) {
                    //start doing something for state - connected
                } else {
                    //start doing something for state - disconnected
                }
            }
        };

        IntentFilter filter = new IntentFilter();
        filter.addAction("android.hardware.usb.action.USB_STATE");

        registerReceiver(receiver, filter);

This BroadcastReceiver will receive actions every time wen usb connected or disconnected.