Bluetooth (Android)

import android.bluetooth.BluetoothAdapter;
import android.util.Log;

public class BluetoothAdapterUtil {

  // logger entry
  private final static String LOG_TAG = BluetoothAdapterUtil.class.getSimpleName();

  private static final int LOOP_WAIT_TIME = 500;

  private static final int MAX_REPETITIONS_COUNT = 30;

  public static void startBluetoothAdapter() {
    try {
      waitUntilBluetoothAdapterIsInState(BluetoothAdapter.STATE_ON, MAX_REPETITIONS_COUNT);
    } catch (Exception e) {
      Log.d(LOG_TAG, e.getMessage());
    }
  }

  public static void stopBluetoothAdapter() {
    try {
      waitUntilBluetoothAdapterIsInState(BluetoothAdapter.STATE_OFF, MAX_REPETITIONS_COUNT);
    } catch (Exception e) {
      Log.d(LOG_TAG, e.getMessage());
    }
  }

  private static void waitUntilBluetoothAdapterIsInState(int state, int remainingLoops) throws Exception {
    BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();

    if(remainingLoops > 0) {
      switch (state) {
      case BluetoothAdapter.STATE_OFF:
        if (bluetoothAdapter.getState() == BluetoothAdapter.STATE_TURNING_OFF) {
          waitNMillis(LOOP_WAIT_TIME);
          waitUntilBluetoothAdapterIsInState(BluetoothAdapter.STATE_OFF, remainingLoops - 1);
        } else if (bluetoothAdapter.getState() == BluetoothAdapter.STATE_OFF) {
          Log.d(LOG_TAG, "BluetoothAdapter is in state OFF");
          return;
        } else {
          // ensure we're not waiting for Godot ;)
          bluetoothAdapter.disable();
          waitUntilBluetoothAdapterIsInState(BluetoothAdapter.STATE_OFF, remainingLoops - 1);
        }
        break;
      case BluetoothAdapter.STATE_ON:
        if (bluetoothAdapter.getState() == BluetoothAdapter.STATE_TURNING_ON) {
          waitNMillis(LOOP_WAIT_TIME);
          waitUntilBluetoothAdapterIsInState(BluetoothAdapter.STATE_ON, remainingLoops - 1);
        } else if (bluetoothAdapter.getState() == BluetoothAdapter.STATE_ON) {
          Log.d(LOG_TAG, "BluetoothAdapter is in state ON");
          return;
        } else {
          // ensure we're not waiting for Godot ;)
          bluetoothAdapter.enable();
          waitUntilBluetoothAdapterIsInState(BluetoothAdapter.STATE_ON, remainingLoops - 1);
        }
        break;
      default:
        throw new Exception(
            "You can check only final states of BluetoothAdapter(STATE_ON|STATE_OFF).");
      }
    } else {
      Log.e(LOG_TAG, "Error on waiting while BluetoothAdapter changes state to #" + state + ". ");
      return;
    }
  }
  private static void waitNMillis(long n) {
    try {
      Thread.sleep(n);
    } catch (InterruptedException e) {
      Log.e(LOG_TAG, "#waitNMillis() " + e.getMessage());
    }
  }

}