因此，我尝试遵循Android Studio教程，了解如何制作蓝牙聊天应用程序，但是做了一些修改以适合我的项目。但是我不是一个聪明的人，对本教程一无所知，只是尝试遵循并复制足够的代码以使其正常工作。
这是代码：
BluetoothDevice mBTDevice;
public ArrayList<BluetoothDevice> mBTDevices = new ArrayList<>();
BluetoothAdapter mBluetoothAdapter;
private OutputStream outputStream;
private InputStream inStream;
private int position;
BluetoothConnectionService mBluetoothConnection;
private static final UUID MY_UUID_INSECURE =
UUID.fromString("8ce255c0-200a-11e0-ac64-0800200c9a66");
/*
*/
private final BroadcastReceiver mBroadcastReceiver4 = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
if(action.equals(BluetoothDevice.ACTION_BOND_STATE_CHANGED)){
BluetoothDevice mDevice = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
//3 cases:
// I think I need just case1
//case1: bonded already
if (mDevice.getBondState() == BluetoothDevice.BOND_BONDED){
Log.d(TAG, "BroadcastReceiver: BOND_BONDED.");
mBTDevice = mDevice;
}
//case2: creating a bond
if (mDevice.getBondState() == BluetoothDevice.BOND_BONDING) {
Log.d(TAG, "BroadcastReceiver: BOND_BONDING.");
}
//case3: breaking a bond
if (mDevice.getBondState() == BluetoothDevice.BOND_NONE) {
Log.d(TAG, "BroadcastReceiver: BOND_NONE.");
}
}
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
GlobalVariables.setmDatabaseHelper(new DatabaseHelper(this));
/*
bluetooth tuto
*/
mBTDevices = new ArrayList<>();
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_BOND_STATE_CHANGED);
registerReceiver(mBroadcastReceiver4, filter);
/*
Calling objects
*/
buttonAdd = (Button) findViewById(R.id.buttonAdd);
buttonNewPill = (Button) findViewById(R.id.buttonNewPill);
buttonSend = (Button) findViewById(R.id.buttonSend);
editText = (EditText) findViewById(R.id.editText);
editText2 = (EditText) findViewById(R.id.editText2);
editText3 = (EditText) findViewById(R.id.editText3);
spinner = (Spinner) findViewById(R.id.spinner);
spinner2 = (Spinner) findViewById(R.id.spinner2);
spinner3 = (Spinner) findViewById(R.id.spinner3);
GlobalVariables.setmDatabaseHelper(new DatabaseHelper(this));
mDatabaseHelper = GlobalVariables.getmDatabaseHelper();
/*
RecyclerView Popualtor
*/
recycler = (RecyclerView) findViewById(R.id.recyclerView);
recycler.setLayoutManager(new LinearLayoutManager(this));
listDatos = new ArrayList<>();
/*
Adapters for spinners
*/
ArrayAdapter<CharSequence> adapterh = ArrayAdapter.createFromResource(this,
R.array.string_h, android.R.layout.simple_spinner_item);
ArrayAdapter<CharSequence> adapterm = ArrayAdapter.createFromResource(this,
R.array.string_m, android.R.layout.simple_spinner_item);
adapterh.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
adapterm.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner2.setAdapter(adapterh);
spinner3.setAdapter(adapterm);
spinner2.setOnItemSelectedListener(this);
spinner3.setOnItemSelectedListener(this);
spinner.setOnItemSelectedListener(new OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
recycler.setAdapter(new AdapterDatos(PillVO.getPills(spinner.getSelectedItem().toString())));
String name = spinner.getSelectedItem().toString();
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
/*
Bluetooth test
*/
/*
Listeners for btns
*/
buttonAdd.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String newEntry = editText.getText().toString();
if (editText.length() > 0) {
AddData(newEntry);
editText.setText("");
} else {
toastMessage("Isn't your field empty?");
}
}
});
buttonNewPill.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String pill_name = editText2.getText().toString();
String pill_module = editText3.getText().toString();
String textSp1 = spinner2.getSelectedItem().toString();
String textSp2 = spinner3.getSelectedItem().toString();
String horario = textSp1 + ":" + textSp2;
String name = spinner.getSelectedItem().toString();
if (editText2.length() > 0 && editText3.length() > 0) {
Integer intNewEntry2 = Integer.parseInt(pill_module);
if (intNewEntry2 <= 10) {
PillVO newPill = new PillVO(pill_module, pill_name, horario, name);
newPill.save();
editText2.setText("");
editText3.setText("");
recycler.setAdapter(new AdapterDatos(PillVO.getPills(spinner.getSelectedItem().toString())));
} else {
toastMessage("Solo hay 10 modulos");
}
} else {
toastMessage("Todos los campos deben ser completados");
}
}
});
/*
Button bluetooth
*/
buttonSend.setOnClickListener(new View.OnClickListener() {
@RequiresApi(api = Build.VERSION_CODES.ICE_CREAM_SANDWICH_MR1)
@Override
public void onClick(View v) {
/*
Collector of Pills
*/
String shower = "";
ArrayList<PillVO> list = PillVO.getPills(spinner.getSelectedItem().toString());
for (PillVO p : list) {
shower += p.getModulo() + ", " + p.getHorario() + "; ";
}
// tuto send
// if "bytes" doesnt work it might be because of charset
//byte[] bytes = etSend.getText().toString().getBytes(Charset.defaultCharset());
IntentFilter discoverDevicesIntent = new IntentFilter(BluetoothDevice.ACTION_FOUND);
enableDisableBT();
startConnection();
//sending string
byte[] bytes = shower.toString().getBytes();
mBluetoothConnection.write(bytes);
}
});
loadSpinnerData();
}
///bt tuto
private void startConnection() {
startBTConnection(mBTDevice, MY_UUID_INSECURE);
}
public void startBTConnection(BluetoothDevice device, UUID uuid) {
Log.d(TAG, "startBTConnection: Initializing RFCOM Bluetooth Connection.");
mBluetoothConnection.StartClient(device, uuid);
}
/// tuto, not needed?
public void enableDisableBT() {
if (mBluetoothAdapter == null) {
Log.d(TAG, "enableDisableBT: Does not have BT capabilities.");
}
if (!mBluetoothAdapter.isEnabled()) {
Intent enableBTIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivity(enableBTIntent);
}
}
public void AddData(String newEntry) {
boolean insertData = mDatabaseHelper.addData(newEntry);
if (insertData) {
toastMessage("Data Succesfully entered");
} else {
toastMessage("Oopos! Something went wrong");
}
loadSpinnerData();
}
/*
Not useful anymore because of PillVO save function
*/
private void AddData2(String newEntry1, String newEntry2, String horario, Integer id_ppl) {
boolean insertData = mDatabaseHelper.addData2(newEntry1, newEntry2, horario, id_ppl);
}
/*
spinner populator
*/
private void loadSpinnerData() {
// database handler
DatabaseHelper db = new DatabaseHelper(getApplicationContext());
// Spinner Drop down elements
List<String> lables = db.getAllLabels();
// Creating adapter for spinner
ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this,
android.R.layout.simple_spinner_item, lables);
// Drop down layout style - list view with radio button
dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
// attaching data adapter to spinner
spinner.setAdapter(dataAdapter);
recycler.setAdapter(new AdapterDatos(PillVO.getPills(spinner.getSelectedItem().toString())));
}
private void toastMessage(String message) {
Toast.makeText(this, message, Toast.LENGTH_SHORT).show();
}
/*
Spinner ¿constructors?
*/
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
//first cancel discovery because its very memory intensive.
mBluetoothAdapter.cancelDiscovery();
Log.d(TAG, "onItemClick: You Clicked on a device.");
String deviceName = mBTDevices.get(i).getName();
String deviceAddress = mBTDevices.get(i).getAddress();
Log.d(TAG, "onItemClick: deviceName = " + deviceName);
Log.d(TAG, "onItemClick: deviceAddress = " + deviceAddress);
//create the bond.
//NOTE: Requires API 17+? I think this is JellyBean
if(Build.VERSION.SDK_INT > Build.VERSION_CODES.JELLY_BEAN_MR2){
Log.d(TAG, "Trying to pair with " + deviceName);
mBTDevices.get(i).createBond();
mBTDevice = mBTDevices.get(i);
mBluetoothConnection = new BluetoothConnectionService(MainActivity.this);
}
}
}
我得到的错误是：
java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法'void com.example.user.project.BluetoothConnectionService.StartClient（android.bluetooth.BluetoothDevice，java.util.UUID）'
基本上，您可能需要的另一部分代码在这里：
我在这里不显示它，因为我认为它不是必需的。不是我的。
很抱歉这么简单，但是我什至不知道该如何正确地问我需要什么。但是我的想法是使用电话蓝牙接口进行连接，并使应用程序仅发送一个字符串，但是我想我通过尝试避免一些过程来弄乱了它。如果足够错，我将从头开始教程。