Bluetooth接続が起動するとクラッシュする

Question

私のアプリが起動すると、他のすべての機能は正常に動作しますが、BluetoothボタンをタップしてBluetoothをオンにすると、アプリがクラッシュして停止したことが示されます。ご迷惑をおかけし、ブルートゥースコード全体を貼り付けることはできません。私の最初のブルートゥースを使用してアンドロイドデベロッパーで新しくなった私はどこに間違っていたのか分かりません。どんな助けも大歓迎です。

はここであなたに

public class BluetoothActivity extends Activity { 

private static final String TAG = "BluetoothActivity"; 
private static final int BLUETOOTH_REQUEST = 0; 
private static final int SELECT_SERVER = 1; 
public static final int DATA_RECEIVED = 3; 
public static final int SOCKET_CONNECTED = 4; 

public static final UUID APP_UUID = UUID 
     .fromString("ad7b8520-f5fa-11e4-b939-0800200c9a66"); 
private Button on; 
private Button off; 
private Button server; 
private Button client; 
private TextView tv = null; 

private BluetoothAdapter b_adapter = null; 
private ConnectionThread bluetoothConnect = null; 
private String data; 
private boolean mServerMode; 

private TextView text; 
private ListView pairedList; 
private Set<BluetoothDevice> pairedDevices; 
private ArrayAdapter<String> BTArrayAdapter; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    b_adapter = BluetoothAdapter.getDefaultAdapter(); 
    if (b_adapter == null) { 
     Log.i(TAG, "Bluetooth not supported"); 
     finish(); 
    } 

    setContentView(R.layout.activity_bluetooth); 
    tv = (TextView) findViewById(R.id.textView1); 
    server = (Button) findViewById(R.id.server); 
    server.setOnClickListener(new OnClickListener() { 
     public void onClick(View v) { 
      startAsServer(); 
      mServerMode = true; 
     } 
    }); 

    client = (Button) findViewById(R.id.client); 
    client.setOnClickListener(new OnClickListener() { 
     public void onClick(View v) { 
      selectServer(); 
     } 
    }); 

    if (!b_adapter.isEnabled()) { 
     Intent enableBluetoothIntent = new Intent(
       BluetoothAdapter.ACTION_REQUEST_ENABLE); 
     startActivityForResult(enableBluetoothIntent, BLUETOOTH_REQUEST); 
    } else { 
     setButtonsEnabled(true); 
    } 

} 

protected void onActivityResult(int requestCode, int resultCode, Intent data) { 
    if (requestCode == BLUETOOTH_REQUEST && resultCode == RESULT_OK) { 
     setButtonsEnabled(true); 
    } else if (requestCode == SELECT_SERVER && resultCode == RESULT_OK) { 
     BluetoothDevice device = data.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE); 
     connectToBluetoothServer(device.getAddress()); 
    } 
} 

private void startAsServer() { 
    setButtonsEnabled(false); 
    new AcceptThread(mHandler).start(); 
} 

private void selectServer() { 
    setButtonsEnabled(false); 
    Set<BluetoothDevice> pairedDevices = b_adapter.getBondedDevices(); 
    ArrayList<String> pairedDeviceString = new ArrayList<String>(); 
    if (pairedDevices.size() > 0) { 
     for (BluetoothDevice device : pairedDevices) { 
      pairedDeviceString.add(device.getName() + "\n" 
        + device.getAddress()); 
     } 
    } 

をありがとうまたBluetoothのスレッドlogcatを表示したい人のために

public class ConnectThread extends Thread { 
private BluetoothSocket BTsocket; 
private final BluetoothDevice mDevice; 
private final BluetoothAdapter b_adapter = BluetoothAdapter.getDefaultAdapter(); 
private final Handler mHandler; 

public ConnectThread(String deviceID, Handler handler) { 
    mDevice = b_adapter.getRemoteDevice(deviceID); 
    mHandler = handler; 
    try { 
     BTsocket = mDevice.createRfcommSocketToServiceRecord(BluetoothActivity.APP_UUID); 
    } catch (IOException e){ 
     e.printStackTrace(); 
    } 
} 
public void run() { 
    b_adapter.cancelDiscovery(); 
    try { 
     BTsocket.connect(); 
     manageConnectedSocket(); 
    } catch (IOException connectException) {  
     try { 
      BTsocket.close(); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 
    } 
} 

private void manageConnectedSocket() { 
    ConnectionThread conn = new ConnectionThread(BTsocket, mHandler); 
    mHandler.obtainMessage(BluetoothActivity.SOCKET_CONNECTED, conn).sendToTarget(); 
    conn.start(); 
} 
public void cancel() { 
    try { 
     BTsocket.close(); 
    }catch(IOException e){ 

    } 
} 

}

です。ここにそれがあります。

.BluetoothActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.bluetooth.BluetoothAdapter.isEnabled()' on a null object reference 
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416) 
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
    at android.app.ActivityThread.-wrap11(ActivityThread.java) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:148) 
    at android.app.ActivityThread.main(ActivityThread.java:5417) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
                    Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.bluetooth.BluetoothAdapter.isEnabled()' on a null object reference 
    at com.kenpar.dmsassign2.BluetoothActivity.onCreate(BluetoothActivity.java:80) 
    at android.app.Activity.performCreate(Activity.java:6237) 
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) 
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) 
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)  
    at android.app.ActivityThread.-wrap11(ActivityThread.java)  
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)  
    at android.os.Handler.dispatchMessage(Handler.java:102)  
    at android.os.Looper.loop(Looper.java:148)  
    at android.app.ActivityThread.main(ActivityThread.java:5417)  
    at java.lang.reflect.Method.invoke(Native Method)  
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)  
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)  

Answer 1

あなたBluetoothAdapterが適切に初期化されないことがあります。 LogCatを確認すると、Bluetoothがサポートされていません。メッセージが情報タグに表示されます。今すぐあなたのActivityでNullPointerExceptionを避けるために、このようにコードを変更します。

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    b_adapter = BluetoothAdapter.getDefaultAdapter(); 
    if (b_adapter == null) { 
     Log.i(TAG, "Bluetooth not supported"); 
     // Show proper message here 
     finish(); 
    } else { 
     setContentView(R.layout.activity_bluetooth); 
     tv = (TextView) findViewById(R.id.textView1); 
     server = (Button) findViewById(R.id.server); 
     server.setOnClickListener(new OnClickListener() { 
      public void onClick(View v) { 
       startAsServer(); 
       mServerMode = true; 
      } 
     }); 

     client = (Button) findViewById(R.id.client); 
     client.setOnClickListener(new OnClickListener() { 
      public void onClick(View v) { 
       selectServer(); 
      } 
     }); 

     if (!b_adapter.isEnabled()) { 
      Intent enableBluetoothIntent = new Intent(
       BluetoothAdapter.ACTION_REQUEST_ENABLE); 
      startActivityForResult(enableBluetoothIntent, BLUETOOTH_REQUEST); 
     } else { 
      setButtonsEnabled(true); 
     } 
    } 
} 

理由がある：あなたのb_adapterがnullであれば、それはそれを使用して行を実行してはいけません。 finishをクリアするには、その隣の行をスキップしないでください。だから、あなたはそれを自分で行う必要があります。