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我是新来的Java编程，我有一个问题。我在使用蓝牙的arduino汽车的控制器工作。该车有3个runnig模式：测试,汽车和手册。我做了一个MainActivity，它有一个布局，每个模式有3个按钮，一个按钮连接用于蓝牙连接。在另一个活动SecondActivity，有另一种布局与控制汽车的方向和速度的按钮，但出人意料地mBluetooth.write不起作用。如何在其他活动中使用蓝牙传输数据？
这是在MainActivity：
public class MainActivity extends AppCompatActivity {
ImageButton test, manual,connect;
Button back;
private BluetoothAdapter mbluetoothAdapter;
protected AlertDialog.Builder builder;
ConnectThread mBluetooth = new ConnectThread();
String mBluetoothName = "";
String mBluetoothAdress = "";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final Context context = this;
//final LayoutInflater factory = getLayoutInflater();
//final View textEntryView = factory.inflate(R.layout.activity_main);
builder = new AlertDialog.Builder(this);
mbluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
connect = (ImageButton) findViewById(R.id.connect);
test = (ImageButton) findViewById(R.id.test);
manual = (ImageButton) findViewById(R.id.manual);
test.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(context,SecondActivity.class);
context.startActivity(intent);
}
});
manual.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(context,SecondActivity.class);
context.startActivity(intent);
}
});
connect.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (!mbluetoothAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivity(enableBtIntent);
} else {
if (!mBluetooth.mBluetoothAddress.equals("")) {//if another connection is already exits then close it first
stopAllActivities();
} else {
try {
Intent serverIntent = new Intent(MainActivity.this, DeviceListActivity.class);
startActivityForResult(serverIntent, Helper.REQUEST_CONNECT_DEVICE);
} catch (Exception e) {
showToast(getString(R.string.errorOccured) + ": " + e.getMessage());
e.printStackTrace();
}
}
}
}
});
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
switch (requestCode) {
case Helper.REQUEST_CONNECT_DEVICE:
if (resultCode == Activity.RESULT_OK) {
mBluetoothName = data.getExtras().getString(Helper.EXTRA_BLUETOOTH_NAME);
mBluetoothAdress = data.getExtras().getString(Helper.EXTRA_BLUETOOTH_ADDRESS);
// setBluetoothInfo();
showToast(R.string.connectedDevice + mBluetoothName);
if (!mBluetoothAdress.equals("")) {
if (!mBluetooth.connect(mBluetoothAdress)){
}
}
}
break;
}
}
private void showToast(String message) {
Toast.makeText(getApplicationContext(), message, Toast.LENGTH_SHORT).show();
}
private void stopAllActivities() {
mBluetooth.write("S"); //send Stop Signal before it closes the connection
mBluetooth.mBluetoothAddress = ""; // reset address
mBluetooth.close();//close Connection
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
//getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
return super.onOptionsItemSelected(item);
}
@Override
public void onPause() {
if (mbluetoothAdapter != null) {
if (mbluetoothAdapter.isDiscovering()) {
mbluetoothAdapter.cancelDiscovery();
}
}
super.onPause();
}}
这是SecondActivity：
public class SecondActivity extends AppCompatActivity {
final Context context = this;
Button back;
ImageButton btnup, btndown, btnright, btnleft;
ConnectThread mBluetooth = new ConnectThread();//??????
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
back = (Button) findViewById(R.id.back);
back.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(context, MainActivity.class);
context.startActivity(intent);
}
});
btnup = (ImageButton) findViewById(R.id.btnup);
btndown = (ImageButton) findViewById(R.id.btndown);
btnleft = (ImageButton) findViewById(R.id.btnleft);
btnright = (ImageButton) findViewById(R.id.btnright);
final TextView direction = (TextView) findViewById(R.id.text_direction);
final TextView steering = (TextView) findViewById(R.id.steering_direction);
final Chronometer chronometer = (Chronometer) findViewById(R.id.chronometer);
btndown.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
mBluetooth.write("2");
direction.setText(R.string.Backwards);
} else if (event.getAction() == MotionEvent.ACTION_UP) {
mBluetooth.write("x");
direction.setText(R.string.blank);
}
return false;
}
});
btnup.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
mBluetooth.write("8");
direction.setText(R.string.Forward);
} else if (event.getAction() == MotionEvent.ACTION_UP) {
mBluetooth.write("z");
direction.setText(R.string.blank);
}
return false;
}
});
btnright.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
mBluetooth.write("6");
steering.setText(R.string.Right);
} else if (event.getAction() == MotionEvent.ACTION_UP) {
mBluetooth.write("c");
steering.setText(R.string.none);
}
return false;
}
});
btnleft.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
mBluetooth.write("4");
steering.setText(R.string.Left);
} else if (event.getAction() == MotionEvent.ACTION_UP) {
mBluetooth.write("v");
steering.setText(R.string.none);
}
return false;
}
});
}}
我测试了蓝牙连接和代码按钮在一个活动和工作的罚款