Question

我的Android应用程序需要一些帮助。我正在尝试创建一个发现蓝牙设备的应用程序，然后将名称与字符串进行比较。但我遇到了两个问题。

1：当我退出应用程序（后退按钮）时，它退出然后显示一条崩溃消息（几秒钟后）..我认为问题出在“mReceiver”上（检查“第二个问题”）。

2 :(主要问题）在下面的代码中，$“mReceiver = new BroadcastReceiver（）”部分有问题。我已经抛出了多个吐司，只是为了检查哪个部分不起作用，此行之前的所有内容都能正常工作。

我不确定，但我认为在开头宣布“mReciver”时没有“最终”的问题 - ＆gt; “私有BroadcastReceiver mReceiver;”。然而，添加最终会导致问题。

守则：

public class MainActivity extends Activity {

private final static int REQUEST_ENABLE_BT = 1; //It's really just a number that you provide for onActivityResult (>0)

//Temp objects for testing
private String StringMeeting = "meeting";
ProgressBar bar;

//Member fields
private BluetoothAdapter mBluetoothAdapter;
private ArrayAdapter<String> mPairedDevicesArrayAdapter;
private ArrayAdapter<String> mNewDevicesArrayAdapter;

// Create a BroadcastReceiver for ACTION_FOUND
private BroadcastReceiver mReceiver;

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

    //declare & start progress bar
    bar = (ProgressBar) findViewById(R.id.progressBar1);
    bar.setVisibility(View.VISIBLE);

    //------------Setup a Bluetooth (Get Adapter) ------------------
    mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    if (mBluetoothAdapter == null) {
        // Device does not support Bluetooth
        Toast.makeText(getApplicationContext(), "This Device does not support Bluetooth", Toast.LENGTH_LONG).show();
    }else{Toast.makeText(getApplicationContext(), "Getting the Adabter is done", Toast.LENGTH_SHORT).show();}


    //------------Setup a Bluetooth (Enable Bluetooth) ------------------
    if (!mBluetoothAdapter.isEnabled()) {
        Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
        startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
    }else{Toast.makeText(getApplicationContext(), "Enable Bluetooth is done", Toast.LENGTH_SHORT).show();}

    //------------Finding Devices (Discovering Devices)----------------------
    // Create a BroadcastReceiver for ACTION_FOUND
    Toast.makeText(getApplicationContext(), "creating the mReceiver", Toast.LENGTH_SHORT).show(); //last thing works
    mReceiver = new BroadcastReceiver() {
        public void onReceive(Context context, Intent intent) {
            Toast.makeText(getApplicationContext(), "accessed onReceive + will create action", Toast.LENGTH_SHORT).show();
            String action = intent.getAction();

            Toast.makeText(getApplicationContext(), "Waiting to discover a device", Toast.LENGTH_SHORT).show();
            // When discovery finds a device
            if (BluetoothDevice.ACTION_FOUND.equals(action)) {
                Toast.makeText(getApplicationContext(), "enterd the if", Toast.LENGTH_SHORT).show();
                // Get the BluetoothDevice object from the Intent
                BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                Toast.makeText(getApplicationContext(), "Getting device names", Toast.LENGTH_SHORT).show();
                Toast.makeText(getApplicationContext(), device.getName(), Toast.LENGTH_LONG).show();
                Toast.makeText(getApplicationContext(), "displaying the name should be done", Toast.LENGTH_SHORT).show();

                // Add the name and address to an array adapter to show in a ListView
                mNewDevicesArrayAdapter.add(device.getName() + "\n" + device.getAddress());

            }else{Toast.makeText(getApplicationContext(), "Error: BluetoothDevice.ACTION_FOUND.equals(action) = False", Toast.LENGTH_SHORT).show();}
        }
    };
    // Register the BroadcastReceiver
    IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
    registerReceiver(mReceiver, filter); // Don't forget to unregister during onDestroy


} //onCreate end

@Override
protected void onDestroy() {
    // TODO Auto-generated method stub
    super.onDestroy();

    // Make sure we're not doing discovery anymore
    if (mBluetoothAdapter != null) {
        mBluetoothAdapter.cancelDiscovery();
    }

    // Unregister broadcast listeners
    this.unregisterReceiver(mReceiver);
}
}

谢谢你的时间。

Answer 1

您启动结果活动，以便提示用户是否允许用户启用蓝牙，但您不等待结果并尝试立即查找设备。

您应该实现onActivityResult回调。如果结果是RESULT_OK，那么您开始发现设备。启用蓝牙需要一些时间。

Android：发现蓝牙设备时出错

1 个答案: