Question

我正在尝试用另一个片段替换ViewPager中的一个片段。

寻呼机由两个页面组成：Fragment1，Fragment2 在fragment2里面，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，我希望它被破坏而不再存在。

实施代码：

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"/>

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：

我试着在适配器中实现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new，然后调用notifyDataSetChanged？还会在收到通知时添加到您的SectionsPageAdapter强制重绘ViewPager。

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

效率不高，但足以达到您的目的。适配器：

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

Answer 2

归零是因为

SectionsPageAdapter adapter = new SectionsPageAdapter(getSupportFragmentManager());

重复了两次，我在标签

中使用替换片段解决了我的问题

替换ViewPager中的片段

2 个答案: