如何使用按钮切换片段中的选项卡？

Question

我有一个标签Activity与几个标签Fragments。 （如艺术家，播放列表，专辑）。我想添加一个按钮到我的家Fragment，点击后将导航到其他标签。例如：我点击播放列表，然后将3个选项卡放到播放列表中。我不知道如何去做这件事。

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
    View rootView = inflater.inflate(
      R.layout.fragment_home, container, false); 
    playlists = (Button) rootView.findViewById(R.id.playlists); 
    playlists.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      //getActivity().getTabHost().setCurrentTabByTag("TAB2"); 
      //viewPager.setCurrentItem(2); 


     } 
    }); 


    return rootView; 
} 

Answer 1

声明一个接口HomeFragment并宣布听者变量

private HomeFragmentActionListener mListener; 

    public interface HomeFragmentActionListener { 
      void onButtonClick(int pos); 
     } 

在HomeFragment类中设置此监听器变量。

public void setListener(
      HomeFragmentActionListener listener) { 
     mListener = listener; 
    } 

和onButton单击通知监听

playlists.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      //getActivity().getTabHost().setCurrentTabByTag("TAB2"); 
      //viewPager.setCurrentItem(2); 
      mListener.onButtonClick(2); 
     } 
    }); 

实现此接口MainFragment

public class MainFragment extends Fragment { 

private class HomeFragmentListener implements HomeFragment.HomeFragmentActionListener { 
public void onButtonClick(int pos) { 
//Change the tabs. 
} 
} 
and set the listener in setupviewpager 
private void setupViewPager(ViewPager viewPager) { 
Adapter adapter = new Adapter(getChildFragmentManager()); 
HomeFragment homeFragment = new HomeFragment(); 
homeFragment.setListener(new HomeFragmentListener()); 
adapter.addFragment(homeFragment, this.getString(R.string.Homecap)); 
.. 

Answer 2

你需要通过回调来通知父活动：

public class MainActivity extends AppCompatActivity implements HomeFragment.Listener { 

    private ViewPager viewPager; 
    ... 

    @Override 
    public void onPlaylistButtonClicked() { 
     // Show playlist tab (assuming playlist is the third tab). 
     viewPager.setCurrentItem(2); 
    } 
} 

而且你的片段：

public class HomeFragment extends Fragment { 

    private Listener callback; 

    @Override 
    public void onAttach(Context context) { 
     super.onAttach(context); 

     // This makes sure that the container activity has implemented the callback interface. 
     try { 
      callback = (Listener) context; 
     } catch (ClassCastException e) { 
      throw new ClassCastException(context.toString() 
        + " must implement Listener"); 
     } 
    } 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
     View rootView = inflater.inflate(
       R.layout.fragment_home, container, false); 
     playlists = (Button) rootView.findViewById(R.id.playlists); 
     playlists.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       callback.onPlaylistButtonClicked(); 
      } 
     }); 

     return rootView; 
    } 

    public interface Listener { 
     void onPlaylistButtonClicked(); 
    } 
}