爲什麼我不能初始化另一個類的方法藍牙

Question

這是我最近發佈的後續場景，其中我試圖調用另一個類的方法並響應TextView的更改。現在我試圖添加初始化該方法的藍牙適配器（BluetoothOn），但是，我又遇到了與應用程序停止相同的錯誤。另一方面，如果我在Main方法中聲明BLEadapter，則可以運行該應用程序而不會出現問題。

public class MainActivity extends Activity { 

    private BluetoothAdapter mBluetoothAdapter; 
    private static final int REQUEST_ENABLE_BT = 1; 

     private TextView textView; 
     //private View myView; 
     Button button; 

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

       textView =(TextView)findViewById(R.id.textView1); 
       addListenerOnButton(); 
      } 

      private void addListenerOnButton() { 
       button = (Button) findViewById(R.id.button1); 

       button.setOnClickListener(new OnClickListener() { 

        @Override 
        public void onClick(View arg0) { 

         enableBluetooth(arg0); 
        } 

       }); 
      } 

      @Override 
      public boolean onCreateOptionsMenu(Menu menu) { 
       // Inflate the menu; this adds items to the action bar if it is present. 
       getMenuInflater().inflate(R.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(); 
       if (id == R.id.action_settings) { 
        return true; 
       } 
       return super.onOptionsItemSelected(item); 
      } 

      public void enableBluetooth (View view){  

      BluetoothOn ble = new BluetoothOn(); 
      ble.initializeBlue(textView); 



      }  
} 

在我的藍牙類

public class BluetoothOn extends MainActivity { 

     private TextView textView1; 

     private BluetoothAdapter mBluetoothAdapter; 
     private static final int REQUEST_ENABLE_BT = 1; 

     public void initializeBlue(View myView){ 

      String BleisOn = "Bluetooth enabled !!!!"; 

      textView1 = (TextView)myView.findViewById(R.id.textView1); 
      textView1.setText(BleisOn); 


      // Initializes Bluetooth adapter. 
      final BluetoothManager bluetoothManager = 
      (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE); 
      mBluetoothAdapter = bluetoothManager.getAdapter(); 

      // Ensures Bluetooth is available on the device and it is enabled. If not, 
      // displays a dialog requesting user permission to enable Bluetooth. 
      if (mBluetoothAdapter == null || !mBluetoothAdapter.isEnabled()) { 
      Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE); 
      startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT); 
         } 
     } 

} 

誰能給我知識上我怎麼能叫從我的主要活動方式，不會導致應用程序崩潰。我只是一個初學者，請詳細解釋我需要什麼東西，我只想在主體外創建其他類，並在用戶與Android應用程序交互後調用方法。我認爲我只是沒有正確地將值傳遞給其他類，這就是爲什麼它不能在android上工作...一旦我點擊分配的按鈕，應用程序崩潰。我需要什麼這個代碼..這裏的路是我以前的帖子鏈接，creating a separate class without a user interface請幫忙謝謝好心人......

這裏是日誌貓

09-01 13:26:27.307: I/ActivityManager(19336): Timeline: Activity_idle id: android.os.BinderProxy@42d54610 time:341763403 
09-01 13:26:39.627: D/AndroidRuntime(21289): Shutting down VM 
09-01 13:26:39.627: W/dalvikvm(21289): threadid=1: thread exiting with uncaught exception (group=0x4156cd88) 
09-01 13:26:39.627: E/AndroidRuntime(21289): FATAL EXCEPTION: main 
09-01 13:26:39.627: E/AndroidRuntime(21289): Process: com.example.thisapp, PID: 21289 
09-01 13:26:39.627: E/AndroidRuntime(21289): java.lang.IllegalStateException: System services not available to Activities before onCreate() 
09-01 13:26:39.627: E/AndroidRuntime(21289): at android.app.Activity.getSystemService(Activity.java:4532) 
09-01 13:26:39.627: E/AndroidRuntime(21289): at com.example.thisapp.BluetoothOn.initializeBlue(BluetoothOn.java:27) 
09-01 13:26:39.627: E/AndroidRuntime(21289): at com.example.thisapp.MainActivity.enableBluetooth(MainActivity.java:71) 
09-01 13:26:39.627: E/AndroidRuntime(21289): at com.example.thisapp.MainActivity$1.onClick(MainActivity.java:43) 
09-01 13:26:39.627: E/AndroidRuntime(21289): at android.view.View.performClick(View.java:4569) 
09-01 13:26:39.627: E/AndroidRuntime(21289): at android.view.View$PerformClick.run(View.java:18553) 
09-01 13:26:39.627: E/AndroidRuntime(21289): at android.os.Handler.handleCallback(Handler.java:733) 
09-01 13:26:39.627: E/AndroidRuntime(21289): at android.os.Handler.dispatchMessage(Handler.java:95) 
09-01 13:26:39.627: E/AndroidRuntime(21289): at android.os.Looper.loop(Looper.java:212) 
09-01 13:26:39.627: E/AndroidRuntime(21289): at android.app.ActivityThread.main(ActivityThread.java:5151) 
09-01 13:26:39.627: E/AndroidRuntime(21289): at java.lang.reflect.Method.invokeNative(Native Method) 
09-01 13:26:39.627: E/AndroidRuntime(21289): at java.lang.reflect.Method.invoke(Method.java:515) 
09-01 13:26:39.627: E/AndroidRuntime(21289): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:877) 
09-01 13:26:39.627: E/AndroidRuntime(21289): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:693) 
09-01 13:26:39.627: E/AndroidRuntime(21289): at dalvik.system.NativeStart.main(Native Method) 
09-01 13:26:41.487: I/Process(21289): Sending signal. PID: 21289 SIG: 9 

Answer 1

有一個一些問題與您的代碼：

1. BluetoothOn不應該有extends MainActivity。

2. BluetoothOn不應該知道任何UI組件。將View傳遞給initializeBlue()方法是一個糟糕的設計決策。請參閱this answer以瞭解有關如何將您的UI邏輯與藍牙邏輯分開的建議。