Enable bluetooth:

BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();

Enable bluetooth:
if (!mBluetoothAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}





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

if (!mBluetoothAdapter.isEnabled()) {
mBluetoothAdapter.enable();
} else {
mBluetoothAdapter.disable();

}

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