java - 缺少选项卡名称和选项卡名称在 android studio 上不会更改

Question

我的主要 Activity 是使用选项卡打开 SearchActivity，我打开了 3 个选项卡，当我运行应用程序时，我只看到 2 个选项卡，并且选项卡名称不会从选项卡 1、选项卡 2 更改为我配置的内容。

公共(public)类 MainActivity 扩展 AppCompatActivity {

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

    //Open search window
    Button button = findViewById(R.id.buttonSearch);
    button.setOnClickListener(new View.OnClickListener() {
        /**
         * Called when a view has been clicked.
         *
         * @param v The view that was clicked.
         */
        @Override
        public void onClick(View v) {
            openSearchActivity();
        }
    });
}

public void openSearchActivity() {
    Intent intent = new Intent(this, SearchActivity.class);
    startActivity(intent);
}

}

公共(public)类 SearchActivity 扩展了 AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_search);
    SectionsPagerAdapter sectionsPagerAdapter = new SectionsPagerAdapter(this, getSupportFragmentManager());
    ViewPager viewPager = findViewById(R.id.view_pager);
    viewPager.setAdapter(sectionsPagerAdapter);
    TabLayout tabs = findViewById(R.id.tabs);
    tabs.setupWithViewPager(viewPager);
    FloatingActionButton fab = findViewById(R.id.fab);

    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });
}

public class SectctionPagerAdapter extends FragmentPagerAdapter {
    /**
     * Constructor for {@link FragmentPagerAdapter} that sets the fragment manager for the adapter.
     * This is the equivalent of calling {@link #( FragmentManager , int)} and
     * passing in {@link #BEHAVIOR_SET_USER_VISIBLE_HINT}.
     *
     * <p>Fragments will have {@link Fragment#setUserVisibleHint(boolean)} called whenever the
     * current Fragment changes.</p>
     *
     * @param fm fragment manager that will interact with this adapter
     * @deprecated use {@link #(FragmentManager, int)} with
     * {@link #BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT}
     */
    public SectctionPagerAdapter(@NonNull FragmentManager fm) {
        super(fm);
    }

    /**
     * Return the Fragment associated with a specified position.
     *
     * @param position
     */
    @NonNull
    @Override
    public Fragment getItem(int position) {
        switch (position) {
            case 0:
                return new BuildingTabOne();
            case 1:
                return new BuildingTabTwo();
            case 2:
                return new BuildingTabThree();
            default:
                return null;
        }
    }

    public CharSequence getPageTitle(int position) {
        switch (position) {
            case 0:
                return "T15";
            case 1:
                return "Y3";
            case 2:
                return "T21";
        }
        return null;
    }

    /**
     * Return the number of tabs available.
     */
    @Override
    public int getCount() {
        return 3;
    }
}

}

示例一个选项卡:

public class BuildingTabTwo extends Fragment {
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.building_tab_two, container, false);
        return view;
    }
}

我做错了什么？

编辑:添加布局:主要:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">
    <Button
            android:text="Search"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:id="@+id/buttonSearch"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintTop_toTopOf="parent" app:layout_constraintVertical_bias="0.919"
            app:layout_constraintStart_toStartOf="parent" app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintEnd_toEndOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>

搜索:

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
        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=".SearchActivity">

    <com.google.android.material.appbar.AppBarLayout
            android:layout_height="wrap_content"
            android:layout_width="match_parent"
            android:theme="@style/AppTheme.AppBarOverlay">

        <TextView
                android:id="@+id/title"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:gravity="center"
                android:minHeight="?actionBarSize"
                android:padding="@dimen/appbar_padding"
                android:text="@string/app_name"
                android:textAppearance="@style/TextAppearance.Widget.AppCompat.Toolbar.Title"/>

        <com.google.android.material.tabs.TabLayout
                android:id="@+id/tabs"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:background="?attr/colorPrimary"/>
    </com.google.android.material.appbar.AppBarLayout>

    <androidx.viewpager.widget.ViewPager
            android:id="@+id/view_pager"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:layout_behavior="@string/appbar_scrolling_view_behavior"/>

    <com.google.android.material.floatingactionbutton.FloatingActionButton
            android:id="@+id/fab"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="bottom|end"
            android:layout_margin="@dimen/fab_margin"
            app:srcCompat="@android:drawable/ic_dialog_email"/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>

标签布局:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent">

</LinearLayout>

Answer 1

tablayout 和 viewpager 必须在一起。你能试试这个代码吗？

应该是这样的

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout 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=".SearchActivity">

    <com.google.android.material.appbar.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <TextView
            android:id="@+id/title"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:minHeight="?actionBarSize"
            android:padding="@dimen/appbar_padding"
            android:text="@string/app_name"
            android:textAppearance="@style/TextAppearance.Widget.AppCompat.Toolbar.Title" />

        <androidx.viewpager.widget.ViewPager
            android:id="@+id/view_pager"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:layout_behavior="@string/appbar_scrolling_view_behavior">

            <com.google.android.material.tabs.TabLayout
                android:id="@+id/tabs"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:background="?attr/colorPrimary" />
        </androidx.viewpager.widget.ViewPager>
    </com.google.android.material.appbar.AppBarLayout>

    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        android:layout_margin="@dimen/fab_margin"
        app:srcCompat="@android:drawable/ic_dialog_email" />
</androidx.coordinatorlayout.widget.CoordinatorLayout>