TabLayout+ViewPager2是最常被用來實現帶有標籤的滑動視圖的其中一種方法之一。

常用的屬性設置

簡單使用(動態生成頁面和對應標籤)

• 效果圖
  
  步驟：
  1. 創建一個用來顯示各標籤畫面的Fragment
     (剩下的步驟都在主頁面(含有TabLayout和ViewPager的頁面)進行操作
  2. 在佈局添加TabLayout和ViewPager2控件
  3. 創建一個List儲存需顯示的標籤Title文字
  4. 設置ViewPager2的Adapter, 用以創建第一步所準備的Fragment和傳值操作。
  5. 創建TabLayoutMediator來把TabLayout與ViewPager2控件進行連動, 並設置tab標籤文字。

常見操作方法：

• ViewPager2.setCurrentItem：用以設置初始選中項之索引, 預設為0
• ViewPager2.registerOnPageChangeCallback：用以設置ViewPager2相關操作的監聽。
  其中常用的回調有：
  • onPageSelected：當tab選中項更改時調用。

Step 1

創建一個用來顯示各標籤畫面的Fragment

• fragment_collection.xml

  <?xml version="1.0" encoding="utf-8"?>
  <FrameLayout 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=".CollectionFragment">
  
      <androidx.constraintlayout.widget.ConstraintLayout
          android:layout_width="match_parent"
          android:layout_height="match_parent">
  
          <TextView
              android:id="@+id/page_text"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:text="TextView"
              android:textSize="24sp"
              app:layout_constraintBottom_toBottomOf="parent"
              app:layout_constraintEnd_toEndOf="parent"
              app:layout_constraintStart_toStartOf="parent"
              app:layout_constraintTop_toTopOf="parent" />
  
      </androidx.constraintlayout.widget.ConstraintLayout>
  
  </FrameLayout>
  

• CollectionFragment.java

public class CollectionFragment extends Fragment {
    public static final String ARG_LABEL = "ARG_Label";
    public static final String ARG_INDEX = "ARG_Index";
    private static FragmentCollectionBinding binding;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        // Inflate the layout for this fragment
//        return inflater.inflate(R.layout.fragment_a, container, false);
        binding = FragmentCollectionBinding.inflate(inflater, container, false);
        return binding.getRoot();
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        Bundle args = getArguments();
        assert args != null;
        int pageInd = args.getInt(ARG_INDEX);
        String pageLabel = args.getString(ARG_LABEL);
        // 顯示頁面索引和標籤值。
        StringBuilder pageTextStr = new StringBuilder().append("[").append(pageInd+1).append("] ").append(pageLabel);
        binding.pageText.setText(pageTextStr);
    }
}

Step 2

在佈局添加TabLayout和ViewPager2控件

• activity_main.xml
  

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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">

    <com.google.android.material.tabs.TabLayout
        android:id="@+id/tabLayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:tabGravity="start"
        app:tabMode="auto" />
    
    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/view_pager"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/tabLayout">

    </androidx.viewpager2.widget.ViewPager2>
</androidx.constraintlayout.widget.ConstraintLayout>

• MainActvity.java

public class MainActivity extends AppCompatActivity {

    private ActivityMainBinding binding;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding = ActivityMainBinding.inflate(getLayoutInflater());
        setContentView(binding.getRoot());
        // Step3 創建一個List儲存需顯示的標籤文字
        List<String> tabTitles = Arrays.asList("A頁面", "B頁面", "C頁面", "D頁面", "E頁面");

        // Step4 設置viewPager2的Adapter
        binding.viewPager.setAdapter(
            new FragmentStateAdapter(getSupportFragmentManager(), getLifecycle()) {
                @Override
                public int getItemCount() {
                    return tabTitles.size();
                }

                @NonNull
                @Override
                public Fragment createFragment(int position) {
                    Fragment fragment = new CollectionFragment();
                    Bundle bundle = new Bundle();
                    bundle.putString(CollectionFragment.ARG_LABEL, tabTitles.get(position)); // 傳遞標籤值
                    bundle.putInt(CollectionFragment.ARG_INDEX, position); // 傳遞索引值
                    fragment.setArguments(bundle);
                    return fragment;
                }
            }
        );

        // 設置初始選中項
        binding.viewPager.setCurrentItem(1);

        // 設置viewpager滑動監聽
        binding.viewPager.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {
            // 當tab選中項變動時調用
            @Override
            public void onPageSelected(int position) {
                super.onPageSelected(position);
                Toast.makeText(getApplicationContext(), tabTitles.get(position), Toast.LENGTH_SHORT).show();
            }
        });

        // Step5 創建TabLayoutMediator來把`TabLayout`與`ViewPager2`關聯
        new TabLayoutMediator(binding.tabLayout, binding.viewPager,
                (tab, position) -> tab.setText(tabTitles.get(position)+"標籤")
        ).attach();
    }
}

Step 3

創建一個List儲存需顯示的標籤Title文字

List<String> tabTitles = Arrays.asList("A頁面", "B頁面", "C頁面", "D頁面", "E頁面");

Step 4

設置ViewPager2的Adapter, 用以創建第一步所準備的Fragment和傳值操作。

binding.viewPager.setAdapter(
    new FragmentStateAdapter(getSupportFragmentManager(), getLifecycle()) {
        @Override
        public int getItemCount() {
            return tabTitles.size();
        }

        @NonNull
        @Override
        public Fragment createFragment(int position) {
            Fragment fragment = new CollectionFragment();
            Bundle bundle = new Bundle();
            bundle.putString(CollectionFragment.ARG_LABEL, tabTitles.get(position)); // 傳遞標籤值
            bundle.putInt(CollectionFragment.ARG_INDEX, position); // 傳遞索引值
            fragment.setArguments(bundle);
            return fragment;
        }
    }
);

Step 5

創建TabLayoutMediator來把TabLayout與ViewPager2控件進行連動, 並設置tab標籤文字。

new TabLayoutMediator(binding.tabLayout, binding.viewPager,
        (tab, position) -> tab.setText(tabTitles.get(position)+"標籤")
).attach();

其他常見操作

• 設置初始選中項, 預設為0

binding.viewPager.setCurrentItem(1);

• 設置viewpager滑動監聽

binding.viewPager.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {
    // 當tab選中項變動時調用
    @Override
    public void onPageSelected(int position) {
        super.onPageSelected(position);
        Toast.makeText(getApplicationContext(), tabTitles.get(position), Toast.LENGTH_SHORT).show();
    }
});