Android蓝牙应用程序进程被杀死

Question

我是 Android 编程的新手。我有两个类:main 和 btmanager。当我尝试在手机上测试我的应用程序时，我得到的只是一条信息，表明进程已被杀死。我究竟做错了什么 ？

代码实现:

主类:

public class MainActivity extends Activity {

BluetoothAdapter bluetooth = BluetoothAdapter.getDefaultAdapter();

Btmanager manager;


@Override
    public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    if (bluetooth == null)
    {
        Toast.makeText(this, "Bluetooth is not enabled on this device", Toast.LENGTH_LONG).show();
        System.exit(0);
    }


}

@Override
public void onStart()
{
    super.onStart();

    if (!bluetooth.isEnabled()) {
        Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
        startActivityForResult(enableBtIntent, 2);
    }

    manager.run();

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
}




public void closeApp (View view)
{
    System.exit(0);
}
}

Btmanager 类:

public class Btmanager extends Thread {

private final BluetoothSocket mmSocket;
private final BluetoothDevice mmDevice;
public static final UUID myUUID = UUID.fromString("0x1101");
BluetoothAdapter bluetooth = BluetoothAdapter.getDefaultAdapter();

public Btmanager(BluetoothDevice device) {
    // Use a temporary object that is later assigned to mmSocket,
    // because mmSocket is final
    BluetoothSocket tmp = null;
    mmDevice = device;

    // Get a BluetoothSocket to connect with the given BluetoothDevice
    try {
        // MY_UUID is the app's UUID string, also used by the server code
        tmp = device.createRfcommSocketToServiceRecord(myUUID);
    } catch (IOException e) { }
    mmSocket = tmp;
}

public void run() {
    // Cancel discovery because it will slow down the connection
    bluetooth.cancelDiscovery();

    try {
        // Connect the device through the socket. This will block
        // until it succeeds or throws an exception
        mmSocket.connect();
    } catch (IOException connectException) {
        // Unable to connect; close the socket and get out
        try {
            mmSocket.close();
        } catch (IOException closeException) { }
        return;
    }

}

/** Will cancel an in-progress connection, and close the socket */
public void cancel() {
    try {
        mmSocket.close();
    } catch (IOException e) { }
}

Answer 1

我在你的代码中看到了 2 个问题:

1. 您没有实例化Btmanager 对象，当您调用run 时它仍然是null。 (将导致 NullPointerException - 您的应用程序将崩溃)。
2. 您调用run 方法而不是Btmanager 的start 方法。如果你想让run方法中的代码在一个新的线程中运行，你必须调用start。调用run 将导致它在相同 线程中运行。这会阻塞您的 UI 线程，如果阻塞时间过长，可能会导致您的应用崩溃。