How to check if bluetooth is enabled programmatically?
BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (mBluetoothAdapter == null) {
    // Device does not support Bluetooth
} else {
    if (!mBluetoothAdapter.isEnabled()) {
        // Bluetooth is not enable :)
    }
}

<uses-permission android:name="android.permission.BLUETOOTH" />