BottomNavigationView後退按鈕無法正常

Question

工作時是按後退按鈕我的片段被改變爲主頁，但底部的圖標沒有改變。我在這裏發佈了我的所有代碼。如果我從底部導航視圖項目中選擇多個然後兩個導航按鈕，然後當我按回按鈕它將重定向到上次選擇的按鈕項目。

但現在發生了什麼，假設我在最後一個項目上說'通知'[正如你可以在屏幕截圖中看到的]，現在當我按回按鈕時，它會直接帶我到'主頁'按鈕，但我想要的是，它應該首先讓我「搜索」按鈕項，然後到「家」不直接到「家」。

我該如何做到這一點？

這裏的佈局：

<?xml version="1.0" encoding="utf-8"?> 
      <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
       xmlns:tools="http://schemas.android.com/tools" 
       xmlns:design="http://schemas.android.com/apk/res-auto" 
       android:id="@+id/activity_main" 
       android:layout_width="match_parent" 
       android:layout_height="match_parent" 
       android:orientation="vertical" 
       tools:context="com.segunfamisa.sample.bottomnav.MainActivity"> 

       <FrameLayout 
        android:id="@+id/container" 
        android:layout_width="match_parent" 
        android:layout_height="0dp" 
        android:layout_weight="1" 
        android:background="#f1f1f1"> 

       </FrameLayout> 

       <android.support.design.widget.BottomNavigationView 
        android:id="@+id/navigation" 
        android:layout_width="match_parent" 
        android:layout_height="wrap_content" 
        android:layout_gravity="start" 
        design:menu="@menu/bottom_nav_items" /> 
      </LinearLayout> 

這裏的活動：

public class MainActivity extends AppCompatActivity { 
    private static final String SELECTED_ITEM = "arg_selected_item"; 

    private BottomNavigationView mBottomNav; 
    private int mSelectedItem; 

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

     mBottomNav = (BottomNavigationView) findViewById(R.id.navigation); 
     mBottomNav.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() { 
      @Override 
      public boolean onNavigationItemSelected(@NonNull MenuItem item) { 
       selectFragment(item); 
       return true; 
      } 
     }); 

     MenuItem selectedItem; 
     if (savedInstanceState != null) { 
      mSelectedItem = savedInstanceState.getInt(SELECTED_ITEM, 0); 
      selectedItem = mBottomNav.getMenu().findItem(mSelectedItem); 
     } else 
     { 
      selectedItem = mBottomNav.getMenu().getItem(0); 
     } 

     selectFragment(selectedItem); 
    } 

    @Override 
    protected void onSaveInstanceState(Bundle outState) { 
     outState.putInt(SELECTED_ITEM, mSelectedItem); 
     super.onSaveInstanceState(outState); 
    } 

    @Override 
    public void onBackPressed() { 
     MenuItem homeItem = mBottomNav.getMenu().getItem(0); 

     if (mSelectedItem != homeItem.getItemId()) { 
      // select home item 
      // homeItem.setCheckable(true); 

      Log.d("backpressids","**** "+mSelectedItem); 
      selectFragment(homeItem); 

     } else { 

      super.onBackPressed(); 

     } 
    } 

    private void selectFragment(MenuItem item) { 
     Fragment frag = null; 
     item.setCheckable(true); 
     // init corresponding fragment 
     switch (item.getItemId()) { 
      case R.id.menu_home: 

       TabFragmentOne fragmentone = new TabFragmentOne(); 
       FragmentTransaction ft = getSupportFragmentManager().beginTransaction(); 
       ft.replace(R.id.container, fragmentone); 
       ft.commit(); 


       break; 
      case R.id.menu_notifications: 


       TabFragmentThree fragmentone_Three = new TabFragmentThree(); 
       FragmentTransaction ft_three = getSupportFragmentManager().beginTransaction(); 
       ft_three.replace(R.id.container, fragmentone_Three); 
       ft_three.commit(); 

       break; 
      case R.id.menu_search: 


       TabFragmentTwo tabFragmentTwo = new TabFragmentTwo(); 
       FragmentTransaction ft_two = getSupportFragmentManager().beginTransaction(); 
       ft_two.replace(R.id.container,tabFragmentTwo); 
       ft_two.commit(); 


       break; 
     } 

     // update selected item 
     mSelectedItem = item.getItemId(); 


     updateToolbarText(item.getTitle()); 

     if (frag != null) { 
      TabFragmentOne fragmentone = new TabFragmentOne(); 
      FragmentTransaction ft = getSupportFragmentManager().beginTransaction(); 
      ft.replace(R.id.container, fragmentone); 
      ft.commit(); 
     } 
    } 

    private void updateToolbarText(CharSequence text) { 
     ActionBar actionBar = getSupportActionBar(); 
     if (actionBar != null) { 
      actionBar.setTitle(text); 
     } 
    } 


} 

請幫我任何一個.....

Answer 1

您可以使用BottomNavigationView.setSelectedItemId(ITEM_ID)選擇所需MenuItem ：

在onBackPressed()中，使用mBottomNav.setSelectedItemId(R.id.menu_home)或mBottomNav.setSelectedItemId(homeItem.getItemId())。

更新onBackPressed()方法如下：

@Override 
public void onBackPressed() { 
    MenuItem homeItem = mBottomNav.getMenu().getItem(0); 

    if (mSelectedItem != homeItem.getItemId()) { 

     selectFragment(homeItem); 

     // Select home item 
     mBottomNav.setSelectedItemId(homeItem.getItemId()); 
    } else { 
     super.onBackPressed(); 
    } 
} 

希望這將有助於〜