粗糙的底部栏是设置默认项目，在去新的活动

问题描述：

我已经创建了一个Android应用程序，有一个底部导航栏。我使用粗糙的底部导航栏，并传递了每个项目的意图。在每次活动中，我再次创建了底部栏。但问题是，当新的活动被创建时，选择的默认项目被重置。请帮助我。粗糙的底部栏是设置默认项目，在去新的活动

欢迎SO！请访问[如何提出一个好问题]（http://stackoverflow.com/help/how-to-ask）并提供[最小，完整且可验证的示例]（http://stackoverflow.com/help/mcve ）到目前为止你所拥有的。 – Olaia

答

您应该使用片段代替，将您的底部栏放置在您的活动和由其处理的框架布局中。

可以实现类似的东西用下面的代码：

MainActivity.xml

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout 
    xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:app="http://schemas.android.com/apk/res-auto" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent"> 

    <com.roughike.bottombar.BottomBar 
     android:id="@+id/bottomBar" 
     android:layout_width="match_parent" 
     android:layout_alignParentBottom="true" 
     app:bb_tabXmlResource="@xml/bottombar_tabs" 
     android:layout_height="60dp" 
     app:bb_inActiveTabColor="@color/inActiveTabColor" 
     app:bb_inActiveTabAlpha="0.8" 
     app:bb_activeTabAlpha="1" 
     app:bb_showShadow="false"/> 

    <FrameLayout 
     android:id="@+id/fragment_container" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_below="@+id/imageview_logo" 
     android:layout_above="@id/bottomBar" 
     android:layout_alignParentStart="true"> 
    </FrameLayout> 
</RelativeLayout>

MainActivity.java

in your onCreate method(), do the following. 


    bottomBar = (BottomBar) findViewById(R.id.bottomBar); 
    bottomBar.selectTabAtPosition(FIRST_FRAGMENT_INDEX); //Default: FIRST 
    bottomBar.setOnTabSelectListener(new OnTabSelectListener() { 

     private int last_index = FIRST_FRAGMENT_INDEX; 

     @Override 
     public void onTabSelected(@IdRes int tabId) { 

      //Creating the Fragment transaction 
      FragmentTransaction transaction = fragmentManager.beginTransaction(); 

      switch (tabId) { 
       case R.id.tab_SECOND: 
        if (SECOND_FRAGMENT_INDEX > last_index) { 
         FragmentArrayList.get(SECOND_FRAGMENT_INDEX).setEnterTransition(new Slide(Gravity.RIGHT)); 
         //transaction.setCustomAnimations(R.animator.slide_from_right, R.animator.slide_to_left); 
        } else if (SECOND_FRAGMENT_INDEX < last_index) { 
         FragmentArrayList.get(SECOND_FRAGMENT_INDEX).setEnterTransition(new Slide(Gravity.LEFT)); 
         //transaction.setCustomAnimations(R.animator.slide_from_left, R.animator.slide_to_right); 
        } 
        transaction.replace(R.id.fragment_container, FragmentArrayList.get(SECOND_FRAGMENT_INDEX)); 
        last_index = SECOND_FRAGMENT_INDEX; 
        break; 

       case R.id.tab_FIRST: 
        if (FIRST_FRAGMENT_INDEX > last_index) { 
         FragmentArrayList.get(FIRST_FRAGMENT_INDEX).setEnterTransition(new Slide(Gravity.RIGHT)); 
         //transaction.setCustomAnimations(R.animator.slide_from_right, R.animator.slide_to_left); 
        } else if (FIRST_FRAGMENT_INDEX < last_index) { 
         FragmentArrayList.get(FIRST_FRAGMENT_INDEX).setEnterTransition(new Slide(Gravity.LEFT)); 
         //transaction.setCustomAnimations(R.animator.slide_from_left, R.animator.slide_to_right); 
        } 
        transaction.replace(R.id.fragment_container, FragmentArrayList.get(FIRST_FRAGMENT_INDEX)); 
        last_index = FIRST_FRAGMENT_INDEX; 
        break; 

       case R.id.tab_THIRD: 
        if (THIRD_FRAGMENT_INDEX > last_index) { 
         FragmentArrayList.get(THIRD_FRAGMENT_INDEX).setEnterTransition(new Slide(Gravity.RIGHT)); 
         //transaction.setCustomAnimations(R.animator.slide_from_right, R.animator.slide_to_left); 
        } else if (THIRD_FRAGMENT_INDEX < last_index) { 
         FragmentArrayList.get(THIRD_FRAGMENT_INDEX).setEnterTransition(new Slide(Gravity.LEFT)); 
         //transaction.setCustomAnimations(R.animator.slide_from_left, R.animator.slide_to_right); 
        } 
        transaction.replace(R.id.fragment_container, FragmentArrayList.get(THIRD_FRAGMENT_INDEX)); 
        last_index = THIRD_FRAGMENT_INDEX; 
        break; 

       case R.id.tab_FOURTH: 
        if (FOURTH_FRAGMENT_INDEX > last_index) { 
         FragmentArrayList.get(FOURTH_FRAGMENT_INDEX).setEnterTransition(new Slide(Gravity.RIGHT)); 
         //transaction.setCustomAnimations(R.animator.slide_from_right, R.animator.slide_to_left); 
        } else if (FOURTH_FRAGMENT_INDEX < last_index) { 
         FragmentArrayList.get(FOURTH_FRAGMENT_INDEX).setEnterTransition(new Slide(Gravity.LEFT)); 
         //transaction.setCustomAnimations(R.animator.slide_from_left, R.animator.slide_to_right); 
        } 
        transaction.replace(R.id.fragment_container, FragmentArrayList.get(FOURTH_FRAGMENT_INDEX)); 
        last_index = FOURTH_FRAGMENT_INDEX; 
        break; 
      } 
      transaction.commit(); 
     } 

    });

粗糙的底部栏是设置默认项目，在去新的活动

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