Android Studio蓝牙发送数据错误

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

BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (bluetoothAdapter == null) {
    // 设备不支持蓝牙
} else if (!bluetoothAdapter.isEnabled()) {
    // 蓝牙未开启
} else {
    // 蓝牙已开启，可以进行操作
}

Set<BluetoothDevice> pairedDevices = bluetoothAdapter.getBondedDevices();
for (BluetoothDevice device : pairedDevices) {
    if (device.getName().equals("目标设备名称")) {
        // 连接到目标设备
        break;
    }
}

String data = "要发送的数据";
OutputStream outputStream = socket.getOutputStream();
outputStream.write(data.getBytes("UTF-8"));