如何檢測當在按鈕片斷android按下後按鈕？

我有導航抽屜與片段，與5菜單，問題是當我去菜單4，我按後退按鈕應用程序關閉，但我需要的應用程序回到第一個菜單，這是所有的菜單分段。如何檢測當在按鈕片斷android按下後按鈕？

這是主要活動（抽屜式導航）代碼

public class MainActivity extends AppCompatActivity{ 
DrawerLayout mDrawerLayout; 
NavigationView mNavigationView; 
FragmentManager mFragmentManager; 
FragmentTransaction mFragmentTransaction; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    /** 
    *Setup the DrawerLayout and NavigationView 
    */ 

    mDrawerLayout = (DrawerLayout) findViewById(R.id.drawerLayout); 
    mNavigationView = (NavigationView) findViewById(R.id.shitstuff) ; 

    /** 
    * Lets inflate the very first fragment 
    * Here , we are inflating the TabFragment as the first Fragment 
    */ 

    mFragmentManager = getSupportFragmentManager(); 
    mFragmentTransaction = mFragmentManager.beginTransaction(); 
    mFragmentTransaction.replace(R.id.containerView,new Recommendation()).commit(); 
    /** 
    * Setup click events on the Navigation View Items. 
    */ 

    mNavigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() { 
     @Override 
     public boolean onNavigationItemSelected(MenuItem menuItem) { 
      mDrawerLayout.closeDrawers(); 



      if (menuItem.getItemId() == R.id.nav_item_lux_level_recomen) { 
       FragmentTransaction fragmentTransaction = mFragmentManager.beginTransaction(); 
       fragmentTransaction.replace(R.id.containerView,new Recommendation()).commit(); 

      } 

      if (menuItem.getItemId() == R.id.nav_item_room_index_calc) { 
       FragmentTransaction xfragmentTransaction = mFragmentManager.beginTransaction(); 
       xfragmentTransaction.replace(R.id.containerView,new RoomIndex()).commit(); 
      } 

      if (menuItem.getItemId() == R.id.nav_item_utilization_factor_calc) { 
       FragmentTransaction xfragmentTransaction = mFragmentManager.beginTransaction(); 
       xfragmentTransaction.replace(R.id.containerView,new UtilizationFactorCalculator()).commit(); 
      } 

      if (menuItem.getItemId() == R.id.nav_item_conversions) { 
       FragmentTransaction xfragmentTransaction = mFragmentManager.beginTransaction(); 
       xfragmentTransaction.replace(R.id.containerView,new Conversion()).commit(); 
      } 
      if (menuItem.getItemId() == R.id.nav_item_lux) { 
       FragmentTransaction xfragmentTransaction = mFragmentManager.beginTransaction(); 
       xfragmentTransaction.replace(R.id.containerView,new LuxSensor()).commit(); 
      } 


      return false; 
     } 

    }); 

    /** 
    * Setup Drawer Toggle of the Toolbar 
    */ 

    android.support.v7.widget.Toolbar toolbar = (android.support.v7.widget.Toolbar) findViewById(R.id.toolbar); 
    ActionBarDrawerToggle mDrawerToggle = new ActionBarDrawerToggle(this,mDrawerLayout, toolbar,R.string.app_name, 
      R.string.app_name); 

    mDrawerLayout.setDrawerListener(mDrawerToggle); 

    mDrawerToggle.syncState(); 




}

菜單的這一個（片段）

public class LuxSensor extends Fragment { 
TextView textLIGHT_available, textLIGHT_reading; 
FragmentManager mFragmentManager; 
@Nullable 
@Override 
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) { 
    View x = inflater.inflate(R.layout.lux_sensor,null); 
    textLIGHT_reading 
      = (TextView)x.findViewById(R.id.LIGHT_reading); 

    SensorManager mySensorManager = (SensorManager)getActivity().getSystemService(Context.SENSOR_SERVICE); 

    Sensor LightSensor = mySensorManager.getDefaultSensor(Sensor.TYPE_LIGHT); 
    if(LightSensor != null){ 
     mySensorManager.registerListener(
       LightSensorListener, 
       LightSensor, 
       SensorManager.SENSOR_DELAY_NORMAL); 

    }else{ 
     textLIGHT_available.setText("Sensor.TYPE_LIGHT NOT Available"); 
    } 
    FragmentManager fm = getFragmentManager(); 

    return x; 
} 





private final SensorEventListener LightSensorListener 
     = new SensorEventListener(){ 

    @Override 
    public void onAccuracyChanged(Sensor sensor, int accuracy) { 
     // TODO Auto-generated method stub 

    } 

    @Override 
    public void onSensorChanged(SensorEvent event) { 
     if(event.sensor.getType() == Sensor.TYPE_LIGHT){ 
      textLIGHT_reading.setText(event.values[0]+" LUX"); 
     } 
    } 

};

}

我曾嘗試在網上解決方案，但它仍然已關閉

來源

2017-03-17 Josh Parinussa

在片段中創建一個函數，並使用片段對象從onBackpressed（）從活動中調用它。 –

在您的MainActivity

@Override 
public void onBackPressed() 
{ 
    FragmentTransaction fragmentTransaction = mFragmentManager.beginTransaction(); 
    fragmentTransaction.replace(R.id.containerView,new Recommendation()).commit(); 
}

來源

2017-03-17 14:04:34 jorgeavilae

感謝它的工作:)） –

在主要活動中，您需要覆蓋以下功能

@Override 
public void onBackPressed() 
{ 
    // code here to check what fragment you are on and handle that accordingly 
    super.onBackPressed(); // this exits the app. 
}

文檔可以在這裏找到：https://developer.android.com/reference/android/app/Activity.html#onBackPressed()

來源

2017-03-17 13:53:18

***「代碼..檢查你在哪個片段上」*** - 請參閱'getActiveFragment（）'這裏：https://stackoverflow.com/a/15543580/2162226 – gnB

您可以在Android的按鍵監聽使用setOnKeyListener()。然後，如果你要處理的背襯，覆蓋onKey方法：

@Override 
public boolean onKey(View v, int keyCode, KeyEvent event) { 
    if (event.getAction() == KeyEvent.ACTION_UP && keyCode == KeyEvent.KEYCODE_BACK) { 
     // do your thing 
    } 

}

來源

2017-03-17 14:00:28 Yashasvi

後退按鈕不會發送一個關鍵事件，它調用onBackPressed代替。 –

@GabeSechan：國際海事組織，它的工作原理。我已經在Dialog Fragment中測試過了，所以它也應該在fragment中工作。 – Yashasvi

它不起作用。它自2010年以來一直無法使用。後退按鈕和主屏幕按鈕無法通過onKeyPressed進行捕捉。如果你找到了一個它所在的地方，它可能是來自OEM的一個bug或者一個奇怪的操作系統版本。 –

-1

在片段你應該使用這樣的事情：

@Override 
    //Pressed return button - returns to the results menu 
    public void onResume() { 
     super.onResume(); 
     getView().setFocusableInTouchMode(true); 
     getView().requestFocus(); 
     getView().setOnKeyListener(new View.OnKeyListener() { 
      @Override 
      public boolean onKey(View v, int keyCode, KeyEvent event) { 

       if (event.getAction() == KeyEvent.ACTION_UP && keyCode == KeyEvent.KEYCODE_BACK){ 

       //your code 

        return true; 
       } 
       return false; 
      } 
     }); 
    }

來源

2017-03-17 14:11:00

如何檢測當在按鈕片斷android按下後按鈕？

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