在ViewPager中替换片段

Question

我试图用另一个替换ViewPager中的片段之一。

该寻呼机由两个页面组成：片段1，片段2 里面的片段2，有一个按钮。当我点击按钮时，它将用Fragment3替换当前片段Fragment2。对于Fragment2，我希望它被销毁，不再存在。

实现代码：

• 布局activity_main：

  <android.support.v7.widget.Toolbar 
      android:id="@+id/toolbar" 
      android:layout_width="match_parent" 
      android:layout_height="?attr/actionBarSize" 
      android:background="?attr/colorPrimary" 
      app:layout_scrollFlags="scroll|enterAlways" 
      app:popupTheme="@style/AppTheme.PopupOverlay"> 
  
  </android.support.v7.widget.Toolbar> 
  
  <android.support.design.widget.TabLayout 
      android:id="@+id/tabs" 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content"/> 
  

• main_activity：

  private SectionsPageAdapter mSectionsPageAdapter; 
  private ViewPager mViewPager; 
  @Override 
  protected void onCreate(Bundle savedInstanceState) { 
      super.onCreate(savedInstanceState); 
      setContentView(R.layout.activity_main); 
  
      mSectionsPageAdapter = new SectionsPageAdapter(getSupportFragmentManager()); 
  
  
      mViewPager = (ViewPager) findViewById(R.id.container); 
  
      setupViewPager(mViewPager); 
  
      TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs); 
      tabLayout.setupWithViewPager(mViewPager); 
  
      mSectionsPageAdapter.clearAll();    
  
  
  } 
  
  private void setupViewPager(ViewPager viewPager) { 
      SectionsPageAdapter adapter = new SectionsPageAdapter(getSupportFragmentManager()); 
      adapter.addFragment(new Tab1Fragment(), "Tab 1"); 
      adapter.addFragment(new Tab2Fragment(), "Tab 2"); 
      adapter.notifyDataSetChanged() 
      viewPager.setAdapter(adapter); 
  } 
  

• 适配器：

  public class SectionsPageAdapter extends FragmentPagerAdapter { 
  
      private final List<Fragment> mFragmentList = new ArrayList<>(); 
      private final List<String> mFragmentTitleList = new ArrayList<>(); 
  
      public void addFragment(Fragment fragment, String title) { 
       mFragmentList.add(fragment); 
       mFragmentTitleList.add(title); 
      } 
  
      public SectionsPageAdapter(FragmentManager fm) { 
       super(fm); 
      } 
  
      @Override 
      public CharSequence getPageTitle(int position) { 
       return mFragmentTitleList.get(position); 
      } 
  
      @Override 
      public Fragment getItem(int position) { 
       return mFragmentList.get(position); 
      } 
  
      @Override 
      public int getCount() { 
       return mFragmentList.size(); 
      } 
  
  
  } 
  

• Fragment2：

  public class Tab2Fragment extends Fragment { 
      private static final String TAG = "Tab2Fragment"; 
  
      private Button btnTEST; 
  
      @Nullable 
      @Override 
      public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) { 
       View view = inflater.inflate(R.layout.tab2_fragment,container,false); 
       btnTEST = (Button) view.findViewById(R.id.btnTEST2); 
  
       btnTEST.setOnClickListener(new View.OnClickListener() { 
        @Override 
        public void onClick(View view) { 
         Toast.makeText(getActivity(), "TESTING BUTTON CLICK 2", Toast.LENGTH_SHORT).show(); 
        } 
       }); 
  
       return view; 
      } 
  
  } 
  

更新：

我试图在适配器中实现clearAll方法，我注意到了mFragmentList（）返回0为什么？

public void addFragment(Fragment fragment, String title) { 
    mFragmentList.add(fragment); 
    mFragmentTitleList.add(title); 
Log.d("tmz",mFragmentList.size()+" From addFragment"); // return 1 & 2 
} 


@Override 
public int getCount() { 
    return mFragmentList.size(); 
    Log.d("tmz",mFragmentList.size()+"getCount "); // return 2 

} 



public void clearAll(){ 
    Log.d("tmz",mFragmentList.size()+" From addFragment"); // return 0 why ? 
    for(int i=0; i<mFragmentList.size(); i++) 
    fragMan.beginTransaction().remove(mFragmentList.get(i)).commit(); 
    mFragmentList.clear(); 
    mFragmentList=new ArrayList<Fragment>(); 
    notifyDataSetChanged(); 
} 

Answer 1

从mFragmentList（和mFragmentTitleList）中删除并添加新的，然后调用notifyDataSetChanged？也会在通知时添加到您的SectionsPageAdapter强制重绘ViewPager。

public int getItemPosition(Object object) { 
    return POSITION_NONE; 
} 

不是最有效的，但足以满足您的需要。对于适配器：

public void removeLastFragment() { 
    if(mFragmentList.size()==0) 
     return; 
    mFragmentList.remove(mFragmentList.size()-1); 
    mFragmentTitleList.remove(mFragmentTitleList.size()-1); 
} 

Answer 2

对于零，这是因为

SectionsPageAdapter adapter = new SectionsPageAdapter(getSupportFragmentManager()); 

重复两次，我解决我的问题，使用替代