Android活动片段监听器无法单击tablayout中的中间选项卡

Question

我是Android应用程序开发的初学者。 我在HomeActivity Layout实现了Tablayout以及Viewpager和title，以在TextView显示所选片段。 我在布局中放置了three Tabitems 。 我正在实现更新活动标题以在工具栏上显示单击选项卡按钮并找到此链接的解决方案

activity_home.xml

android.support.design.widget.TabLayout
    android:id="@+id/tabLayout"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="1.0"
    app:layout_constraintStart_toStartOf="parent"
    app:tabSelectedTextColor="@color/clinividPink"
    app:tabTextAppearance="@style/MineCustomTabText">

    <android.support.design.widget.TabItem
        android:id="@+id/contactsTabButton"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:icon="@drawable/contacts_tab_state"
        android:text="@string/contacts_tab_name" />

    <android.support.design.widget.TabItem
        android:id="@+id/casesTabButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:icon="@drawable/cases_tab_state"
        android:text="@string/cases_tab_name" />

    <android.support.design.widget.TabItem
        android:id="@+id/profileTabButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:icon="@drawable/profile_tab_state"
        android:text="@string/profile_tab_name" />
</android.support.design.widget.TabLayout>

<android.support.v4.view.ViewPager
    android:id="@+id/contactsVIew"
    android:layout_width="0dp"
    android:layout_height="0dp"
    android:layout_marginTop="8dp"
    app:layout_constraintBottom_toTopOf="@+id/tabLayout"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/toolbar2" />

<TextView
    android:id="@+id/home_activity_title"
    android:layout_width="wrap_content"
    android:layout_height="0dp"
    android:layout_marginStart="8dp"
    android:layout_marginLeft="8dp"
    android:layout_marginTop="12dp"
    android:layout_marginBottom="12dp"
    android:text="Contacts"
    android:textSize="18sp"
    android:textStyle="bold"
    app:layout_constraintBottom_toBottomOf="@+id/toolbar2"
    app:layout_constraintEnd_toEndOf="@+id/toolbar2"
    app:layout_constraintStart_toStartOf="@+id/toolbar2"
    app:layout_constraintTop_toTopOf="@+id/toolbar2" />

viewpager有条件地填充了Fragment适配器，有3个不同的片段。

HomeTabLayoutAdapter.java

public class HomeTabLayoutAdapter extends FragmentPagerAdapter {

private Context myContext;
int totalTabs;

private static final String LOG_TAG = HomeTabLayoutAdapter.class.getSimpleName();

public HomeTabLayoutAdapter(FragmentManager fm, Context myContext, int totalTabs) {
    super(fm);
    this.myContext = myContext;
    this.totalTabs = totalTabs;
}

@Override
public Fragment getItem(int position) {
    switch (position) {
        case 0: {
            Log.d(LOG_TAG, "\nFragment: 0 - Contacts");


            ContactsFragment contactsFragment = new ContactsFragment();
            return contactsFragment;
        }
        case 1: {
            Log.d(LOG_TAG, "\nFragment: 1 - Cases ");
            CasesFragment casesFragment = new CasesFragment();
            return casesFragment;
        }
        case 2: {
            Log.d(LOG_TAG, "\nFragment: 2 - Profile");
            ProfileFragment profileFragment = new ProfileFragment();
            return profileFragment;
        }
        default: {
            Log.d(LOG_TAG, "\nFragment: default");
            return new Fragment();
        }

    }
}

@Override
public int getCount() {
    return totalTabs;
}
}

我的片段看起来像这样

SampleFragment.java

public class CasesFragment extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";

private static final String LOG_TAG = CasesFragment.class.getSimpleName();


// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;

private OnFragmentInteractionListener mListener;

public CasesFragment() {
    // Required empty public constructor
}

public static CasesFragment newInstance(String param1, String param2) 
{
        CasesFragment fragment = new CasesFragment();
        Bundle args = new Bundle();
        args.putString(ARG_PARAM1, param1);
        args.putString(ARG_PARAM2, param2);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);
            mParam2 = getArguments().getString(ARG_PARAM2);
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
        // Inflate the layout for this fragment

        View casesFragmentView = inflater.inflate(R.layout.fragment_cases, container, false);

        Log.d(LOG_TAG, "\nCASES listener: " + mListener);

        if (mListener != null) {
            mListener.onFragmentInteraction("Cases");
        }
        return casesFragmentView;
    }

    // TODO: Rename method, update argument and hook method into UI event
    public void onButtonPressed(Uri uri) {
        if (mListener != null) {
            mListener.onFragmentInteraction(uri);
        }
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        if (context instanceof OnFragmentInteractionListener) {
            mListener = (OnFragmentInteractionListener) context;
        } else {
            throw new RuntimeException(context.toString()
                + " must implement OnFragmentInteractionListener");
        }
    }

    @Override
    public void onDetach() {
        super.onDetach();
        mListener = null;
    }

    public interface OnFragmentInteractionListener {
        // TODO: Update argument type and name
        void onFragmentInteraction(Uri uri);
        String onHomeAndFragment1Listener(String title); // increment number in name for each fragment interface

    }
}

在我的HomeActivity.java中为这三个片段实现了OnFragmentInteractionListener

public class HomeActivity
    extends AppCompatActivity
    implements ContactsFragment.OnFragmentInteractionListener,
               ProfileFragment.OnFragmentInteractionListener,
               CasesFragment.OnFragmentInteractionListener
{

TabLayout tabLayout;
ViewPager viewPager;
TextView homeActivityTitleView;

private static final String LOG_TAG = HomeActivity.class.getSimpleName();


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_home);

    tabLayout=(TabLayout)findViewById(R.id.tabLayout);
    viewPager=(ViewPager)findViewById(R.id.contactsVIew);
    homeActivityTitleView=(TextView) findViewById(R.id.home_activity_title);

    final HomeTabLayoutAdapter adapter = new HomeTabLayoutAdapter(getSupportFragmentManager(), this, tabLayout.getTabCount());
    viewPager.setAdapter(adapter);

    viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));

    tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
        @Override
        public void onTabSelected(TabLayout.Tab tab) {
            Log.d(LOG_TAG, "\nSELECTED tab: " + tab.getPosition());
            viewPager.setCurrentItem(tab.getPosition());
        }

        @Override
        public void onTabUnselected(TabLayout.Tab tab) {
            Log.d(LOG_TAG, "\nUNSELECTED tab: " + tab.getPosition());
        }

        @Override
        public void onTabReselected(TabLayout.Tab tab) {
            Log.d(LOG_TAG, "\nRESELECTED tab: " + tab.getPosition());
        }
    });
    viewPager.setCurrentItem(1);
}


@Override
public String onHomeAndCasesInteraction(String title) {
    Log.d(LOG_TAG, "\nUpdate title: " + title);

    homeActivityTitleView.setText(title);
    return title;
}

@Override
public String onHomeAndContactsInteraction(String title) {;
    Log.d(LOG_TAG, "\nUpdate title: " + title);

    homeActivityTitleView.setText(title);
    return title;
}

@Override
public String onHomeAndProfileInteraction(String title) {
    Log.d(LOG_TAG, "\nUpdate title: " + title);

    homeActivityTitleView.setText(title);
    return title;
}

@Override
public void onFragmentInteraction(Uri uri) {
}

}

tablayout UI工作正常，但是当我点击中间选项卡时，我的activity_home.xml中的活动标题无法正常工作。 它会显示左侧或右侧标签的文本，具体取决于之前选项卡的大小写。 我暂时尝试添加尽可能多的格式，但如果你们需要更多信息，请在评论中告诉我，我会更新。

PS我尝试过添加第4个标签和另一个片段，结果比3个标签更难以预测。 请有人帮助我。

更新答案：

Abhisheik的回答工作，我改变了我的tabLayout.addOnTabSelectedListener在我HomeActivity.java如下除去呼叫从更新标题onCreateView每个片段。

tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
        @Override
        public void onTabSelected(TabLayout.Tab tab) {
            Log.d(LOG_TAG, "\nSELECTED tab: " + tab.getPosition());
            viewPager.setCurrentItem(tab.getPosition());
            switch (tab.getPosition()) {
                case 0: onHomeAndContactsInteraction("Contacts"); return;
                case 1: onHomeAndCasesInteraction("Cases"); return;
                case 2: onHomeAndProfileInteraction("Profile"); return;
                default: onHomeAndCasesInteraction("Cases"); return;
            }
        }

        @Override
        public void onTabUnselected(TabLayout.Tab tab) {
            Log.d(LOG_TAG, "\nUNSELECTED tab: " + tab.getPosition());
        }

        @Override
        public void onTabReselected(TabLayout.Tab tab) {
            Log.d(LOG_TAG, "\nRESELECTED tab: " + tab.getPosition());
        }
    });

Answer 1

当片段与Tabs一起使用时，一些初始制表符的片段会并行实例化。 因此，在片段的onCreateView中调用interactionListener的方法将无济于事。

如果您需要知道选择了哪个选项卡，可以在活动的tabLayout上添加一个监听器

    tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
        @Override
        public void onTabSelected(TabLayout.Tab tab) {
            //do stuff here
        }

        @Override
        public void onTabUnselected(TabLayout.Tab tab) {

        }

        @Override
        public void onTabReselected(TabLayout.Tab tab) {

        }
    });