android - 当我滑动 View 时，选项卡指示器不起作用，但当我选择特定选项卡时，选项卡指示器起作用

Question

当我选择选项卡时，选项卡指示器起作用，但当我滑动时则不起作用。当我添加以下代码时，选项卡指示器也起作用

 tabLayout.setupWithViewPager(viewPager);

即使在滑动时选项卡指示器也开始工作，但选项卡标题不可见

主要 Activity 代码

public class MainActivity extends AppCompatActivity implements 
TabLayout.OnTabSelectedListener{

    private TabLayout tabLayout;
     private ViewPager viewPager;
    //Setting global reminder message,receiver name,uid
    protected static String reminderMessage;
    protected static String recepientUID;
    protected static String recipientName;
    protected static String reminderDate;
    protected static String reminderTime;
    protected static String recepientName;

    //Setting global Username and ID
    protected static String userName;
    protected static String userID;

    private Button signOut;
    private ProgressBar progressBar;
    private FirebaseAuth.AuthStateListener authListener;
    protected static FirebaseAuth auth;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        getSupportActionBar().setDisplayHomeAsUpEnabled(true);


        //Initializing viewPager
        viewPager = (ViewPager) findViewById(R.id.pager);
        //Initializing the tablayout
        tabLayout = (TabLayout) findViewById(R.id.tabLayout);

        //Adding the tabs using addTab() method
        tabLayout.addTab(tabLayout.newTab().setText("Contacts"));
        tabLayout.addTab(tabLayout.newTab().setText("Notifications"));
        tabLayout.addTab(tabLayout.newTab().setText("Response"));
        tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);

        //Creating our pager adapter
        Pager adapter = new Pager(getSupportFragmentManager(), 
        tabLayout.getTabCount());

        //Adding onTabSelectedListener to swipe views
        tabLayout.addOnTabSelectedListener(this);

        tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {

                //THIS!!
                if (viewPager != null) {
                    viewPager.setCurrentItem(tab.getPosition());

                }
            }

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

            }

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

            }
        });
        viewPager.setAdapter(adapter);

        //get firebase auth instance
        auth = FirebaseAuth.getInstance();

        //get current user
        final FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();

        authListener = new FirebaseAuth.AuthStateListener() {
            @Override
            public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
                FirebaseUser user = firebaseAuth.getCurrentUser();
                if (user == null) {
                    // user auth state is changed - user is null
                    // launch login activity
                    startActivity(new Intent(MainActivity.this, LoginActivity.class));
                    finish();
                }
                else{
                    userID = user.getUid();
                }
            }
        };

        if (user == null) {
            // user auth state is changed - user is null
            // launch login activity
            startActivity(new Intent(MainActivity.this, LoginActivity.class));
            finish();
        }
        else{
            userID = user.getUid();
        }


    }
    @Override
    public void onTabSelected(TabLayout.Tab tab) {
        viewPager.setCurrentItem(tab.getPosition());
    }

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

    }

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

    }
}

寻呼机代码

public class Pager extends FragmentStatePagerAdapter {

    //integer to count number of tabs
    int tabCount;

    //Constructor to the class
    public Pager(FragmentManager fm, int tabCount) {
        super(fm);
        //Initializing tab count
        this.tabCount= tabCount;
    }

    //Overriding method getItem
    @Override
    public Fragment getItem(int position) {
        //Returning the current tabs
        switch (position) {
            case 0:
                Tab1 tab1 = new Tab1();
                return tab1;
            case 1:
                Tab2 tab2 = new Tab2();
                return tab2;
            case 2:
                Tab3 tab3 = new Tab3();
                return tab3;
            default:
                return null;
        }
    }

    //Overriden method getCount to get the number of tabs
    @Override
    public int getCount() {
        return tabCount;
    }
}

主要 Activity 代码

<LinearLayout
    android:id="@+id/main_layout"
    android:orientation="vertical"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <!-- our toolbar -->
    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="?attr/colorPrimary"
        android:minHeight="?attr/actionBarSize"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light"/>

    <!-- our tablayout to display tabs  -->
    <android.support.design.widget.TabLayout
        android:id="@+id/tabLayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="?attr/colorPrimary"
        android:minHeight="?attr/actionBarSize"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
        app:tabMode="fixed"
        app:tabGravity="fill"/>

    <!-- View pager to swipe views -->
    <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="fill_parent"/>

</LinearLayout>

Answer 1

tabLayout.setupWithViewPager(viewPager);

这行代码解决了我的问题，同时更新了寻呼机

公共(public)类 Pager 扩展 FragmentStatePagerAdapter {

// tab titles
private String[] tabTitles = new String[]{"Contacts", "Reminders", "Responses"};

public Pager(FragmentManager fm) {
    super(fm);
}

// overriding getPageTitle()
@Override
public CharSequence getPageTitle(int position) {
    return tabTitles[position];
}

@Override
public Fragment getItem(int position) {
    switch (position) {
        case 0:
            return new Tab1();
        case 1:
            return new Tab2();
        case 2:
            return new Tab3();
        default:
            return null;
    }
}

@Override
public int getCount() {
    return tabTitles.length;
}

}