替换 ViewPager 中的片段

Question

我正在尝试用另一个片段替换 ViewPager 中的片段之一。

pager 由两个页面组成： Fragment1 , Fragment2 在fragment2里面，有一个按钮。当我单击该按钮时，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：

• activity_main 的布局：

  <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"/>
  

• 主要活动：

  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();
      }
  
  
  }
  

• 片段2：

  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：

我尝试在适配器中实现 clearAll 方法，我注意到 mFragmentList.size() 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?还可以添加到您的SectionsPageAdapter，以便在收到通知时强制重绘ViewPager。

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

不是最有效的，但足以满足您的目的。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

零是因为

SectionsPageAdapter adapter = new SectionsPageAdapter(getSupportFragmentManager());

重复了两次，我通过在选项卡内使用替换片段解决了我的问题