使用ChildFragmentManager替换片段只是将第二个片段放在第一个片段上

问题描述：

我想使用制表符创建应用程序，并且在每个选项卡中我想要多个片段。我有一个MainActivity：使用ChildFragmentManager替换片段只是将第二个片段放在第一个片段上

import android.support.v4.app.FragmentManager; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.util.Log; 
public class MainActivity extends AppCompatActivity { 
    private CarouselFragment carouselFragment; 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     if (savedInstanceState == null){ 
      initScreen(); 
     }else { 
      carouselFragment = (CarouselFragment) getSupportFragmentManager().getFragments().get(0); 
     } 
    } 
    private void initScreen() { 
     carouselFragment = new CarouselFragment(); 
     Log.v("manager", "init " + getSupportFragmentManager().toString()); 
     final FragmentManager fragmentManager = getSupportFragmentManager(); 
     fragmentManager.beginTransaction() 
       .replace(R.id.container, carouselFragment) 
       .commit(); 
     Log.v("manager", "init " + getSupportFragmentManager().toString()); 
    } 
    @Override 
    public void onBackPressed() { 
     if (!carouselFragment.onBackPressed()) { 
      super.onBackPressed(); 
     } else { 
     } 
    } 
}

的CarouselFragment类：

import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.support.v4.view.ViewPager; 
import android.util.Log; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
public class CarouselFragment extends Fragment { 
    protected ViewPager pager; 
    private ViewPagerAdapter adapter; 
    public CarouselFragment() { 
    } 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
    } 
    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
     View rootView = inflater.inflate(R.layout.fragment_carousel, container, false); 
     pager = (ViewPager) rootView.findViewById(R.id.vp_pages); 
     return rootView; 
    } 
    @Override 
    public void onActivityCreated(Bundle savedInstanceState) { 
     super.onActivityCreated(savedInstanceState); 
     Log.v("manager", "carousel " + getChildFragmentManager().toString()); 
     adapter = new ViewPagerAdapter(getResources(), getChildFragmentManager()); 
     pager.setAdapter(adapter); 
     Log.v("manager", "carousel " + getChildFragmentManager().toString()); 
    } 
    public boolean onBackPressed() { 
     OnBackPressListener currentFragment = (OnBackPressListener) adapter.getRegisteredFragment(pager.getCurrentItem()); 
     if (currentFragment != null) { 
      return currentFragment.onBackPressed(); 
     } 
     return false; 
    } 
}

而且它的XML布局：

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:orientation="vertical" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent"> 
    <android.support.v4.view.ViewPager 
     android:id="@+id/vp_pages" 
     android:layout_width="match_parent" 
     android:layout_height="0dp" 
     android:layout_weight="1" /> 
</LinearLayout>

的ViewPagerAdapter类：

import android.content.res.Resources; 
import android.support.v4.app.Fragment; 
import android.support.v4.app.FragmentManager; 
import android.support.v4.app.FragmentPagerAdapter; 
import android.util.SparseArray; 
import android.view.ViewGroup; 
public class ViewPagerAdapter extends FragmentPagerAdapter { 
    private final Resources resources; 
    SparseArray<Fragment> registeredFragments = new SparseArray<Fragment>(); 
    public ViewPagerAdapter(final Resources resources, FragmentManager fm) { 
     super(fm); 
     this.resources = resources; 
    } 
    @Override 
    public Fragment getItem(int position) { 
     final Fragment result; 
     switch (position) { 
      case 0: 
       result = new A1Fragment(); 
       break; 
      case 1: 
       result = new B1Fragment(); 
       break; 
      case 2: 
       result = new C1Fragment(); 
       break; 
      default: 
       result = null; 
       break; 
     } 
     return result; 
    } 
    @Override 
    public int getCount() { 
     return 3; 
    } 
    @Override 
    public CharSequence getPageTitle(final int position) { 
     switch (position) { 
      case 0: 
       return "a"; 
      case 1: 
       return "b"; 
      case 2: 
       return "c"; 
      default: 
       return null; 
     } 
    } 
    @Override 
    public Object instantiateItem(ViewGroup container, int position) { 
     Fragment fragment = (Fragment) super.instantiateItem(container, position); 
     registeredFragments.put(position, fragment); 
     return fragment; 
    } 
    @Override 
    public void destroyItem(ViewGroup container, int position, Object object) { 
     registeredFragments.remove(position); 
     super.destroyItem(container, position, object); 
    } 
    public Fragment getRegisteredFragment(int position) { 
     return registeredFragments.get(position); 
    } 
}

的A1Fragment类：

import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.support.v4.app.FragmentTransaction; 
import android.util.Log; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
public class A1Fragment extends RootFragment { 
    public A1Fragment() { 
    } 
    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 
     View rootView = inflater.inflate(R.layout.fragment_a1, container, false); 
     rootView.findViewById(R.id.next_button).setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       enterNextFragment(); 
      } 
     }); 
     return rootView; 
    } 
    private void enterNextFragment() { 
     A2Fragment a2Fragment = new A2Fragment(); 
     FragmentTransaction transaction = getChildFragmentManager().beginTransaction(); 
     transaction.addToBackStack(null); 
     transaction.replace(R.id.fragment_mainLayout, a2Fragment).commit(); 
    } 
}

而其XML：

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    tools:context=".frags.A1Fragment" 
    android:background="@android:color/white" 
    android:id="@+id/fragment_mainLayout"> 
    <TextView 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:text="a1" 
     android:textAppearance="?android:textAppearanceLarge" 
     android:textSize="36sp"/> 
    <Button 
     android:id="@+id/next_button" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_gravity="center" 
     android:text="Next fragment"/> 
</FrameLayout>

的A2Fragment类：

import android.os.Bundle; 
import android.support.v4.app.FragmentTransaction; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
public class A2Fragment extends RootFragment { 
    public A2Fragment() { 
    } 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 
     View rootView = inflater.inflate(R.layout.fragment_a2, container, false); 
     rootView.findViewById(R.id.next_button).setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       enterNextFragment(); 
      } 
     }); 
     return rootView; 
    } 

    private void enterNextFragment() { 
     A3Fragment a3Fragment = new A3Fragment(); 
     FragmentTransaction transaction = getChildFragmentManager().beginTransaction(); 
     transaction.addToBackStack(null); 
     transaction.replace(R.id.fragment_mainLayout, a3Fragment).commit(); 
    } 
}

而其XML：

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    tools:context=".frags.A2Fragment" 
    android:background="@android:color/white" 
    android:id="@+id/fragment_mainLayout"> 
    <TextView 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:text="a2" 
     android:textAppearance="?android:textAppearanceLarge" 
     android:textSize="36sp"/> 
    <Button 
     android:id="@+id/next_button" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_gravity="center_horizontal|bottom" 
     android:text="Next fragment"/> 
</FrameLayout>

的问题是，当我替换所述第一片段第二个第一个不会消失。第二个出现在第一个。

心不是那个意思替换字？ – Nanoc

你期待什么样的行为？ – PedroAGSantos

第一个片段的按钮仍然可见并可点击。不，意思是第一个片段应该被删除，第二个被添加，而不是第二个被添加。 –

答

我建议你有使用Android设备监视器视图层次看看。

此外，简化您的代码，您可以：
1）在XML中直接包含CarouselFragment
2）使用FrameLayout里包含您的ViewPager并设置为ViewPager高度MATCH_PARENT

答

嗨，你可以设置背景颜色，以你的第二个片段布局，第一个会不会出现

如何可以我这样做？ –

这不是一个干净的方法，因为第一个片段仍然存在并且仍然可见，所以它可以从第二个片段“捕获”触摸事件。 – yennsarah

那么，有没有办法用第二个片段替换第一个片段呢？ –

使用ChildFragmentManager替换片段只是将第二个片段放在第一个片段上

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