使用 ViewPager2 建立含有分頁的滑動檢視畫面

滑動檢視畫面可讓您透過橫向移動的手勢 (也就是左右「滑動」),在同層級畫面 (如分頁) 之間導覽。這種導覽模式又稱為「橫向分頁」。本主題將說明如何建立包含滑動檢視畫面的分頁版面配置以在分頁之間進行切換,以及如何顯示標題列而不是分頁。

實作滑動檢視畫面

您可以使用 AndroidX 的 ViewPager2 小工具建立滑動檢視畫面。如要使用 ViewPager2 和分頁,您需要向專案中的 ViewPager2Material Components (材質元件) 新增依附元件。

如要透過 ViewPager2 設定版面配置,請將 <ViewPager2> 元素新增到您的 XML 版面配置中。例如,如果滑動檢視畫面中的每個頁面都應耗用整個版面配置,則版面配置應如下所示:

<androidx.viewpager2.widget.ViewPager2
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/pager"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

如要插入代表各個頁面的子檢視畫面,請將這個版面配置掛接到 FragmentStateAdapter。以下說明如何使用它來滑動 Fragment 物件集合:

Kotlin

class CollectionDemoFragment : Fragment() {
    // When requested, this adapter returns a DemoObjectFragment,
    // representing an object in the collection.
    private lateinit var demoCollectionAdapter: DemoCollectionAdapter
    private lateinit var viewPager: ViewPager2

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        return inflater.inflate(R.layout.collection_demo, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        demoCollectionAdapter = DemoCollectionAdapter(this)
        viewPager = view.findViewById(R.id.pager)
        viewPager.adapter = demoCollectionAdapter
    }
}

class DemoCollectionAdapter(fragment: Fragment) : FragmentStateAdapter(fragment) {

    override fun getItemCount(): Int = 100

    override fun createFragment(position: Int): Fragment {
        // Return a NEW fragment instance in createFragment(int)
        val fragment = DemoObjectFragment()
        fragment.arguments = Bundle().apply {
            // Our object is just an integer :-P
            putInt(ARG_OBJECT, position + 1)
        }
        return fragment
    }
}

private const val ARG_OBJECT = "object"

// Instances of this class are fragments representing a single
// object in our collection.
class DemoObjectFragment : Fragment() {

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View {
        return inflater.inflate(R.layout.fragment_collection_object, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        arguments?.takeIf { it.containsKey(ARG_OBJECT) }?.apply {
            val textView: TextView = view.findViewById(android.R.id.text1)
            textView.text = getInt(ARG_OBJECT).toString()
        }
    }
}

Java

public class CollectionDemoFragment extends Fragment {
    // When requested, this adapter returns a DemoObjectFragment,
    // representing an object in the collection.
    DemoCollectionAdapter demoCollectionAdapter;
    ViewPager2 viewPager;

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container,
            @Nullable Bundle savedInstanceState) {
        return inflater.inflate(R.layout.collection_demo, container, false);
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        demoCollectionAdapter = new DemoCollectionAdapter(this);
        viewPager = view.findViewById(R.id.pager);
        viewPager.setAdapter(demoCollectionAdapter);
    }
}

public class DemoCollectionAdapter extends FragmentStateAdapter {
    public DemoCollectionAdapter(Fragment fragment) {
        super(fragment);
    }

    @NonNull
    @Override
    public Fragment createFragment(int position) {
        // Return a NEW fragment instance in createFragment(int)
        Fragment fragment = new DemoObjectFragment();
        Bundle args = new Bundle();
        // Our object is just an integer :-P
        args.putInt(DemoObjectFragment.ARG_OBJECT, position + 1);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public int getItemCount() {
        return 100;
    }
}

// Instances of this class are fragments representing a single
// object in our collection.
public class DemoObjectFragment extends Fragment {
    public static final String ARG_OBJECT = "object";

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container,
            @Nullable Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_collection_object, container, false);
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        Bundle args = getArguments();
        ((TextView) view.findViewById(android.R.id.text1))
                .setText(Integer.toString(args.getInt(ARG_OBJECT)));
    }
}

下列各節說明如何新增分頁,以便瀏覽頁面。

使用 TabLayout 新增分頁

TabLayout 可讓您以橫向排列的方式顯示分頁。與 ViewPager2 搭配使用時,TabLayout 可提供熟悉的介面,以便在滑動檢視畫面中瀏覽頁面。

圖 1:含有四個分頁的 TabLayout

如要在 ViewPager2 中加入 TabLayout,請在 <ViewPager2> 元素上方加入 <TabLayout> 元素,如下所示:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <com.google.android.material.tabs.TabLayout
        android:id="@+id/tab_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

</LinearLayout>

接下來,請建立 TabLayoutMediator 以將 TabLayout 連結至 ViewPager2,並依下列方式附加:

Kotlin

class CollectionDemoFragment : Fragment() {
    ...
    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        val tabLayout = view.findViewById(R.id.tab_layout)
        TabLayoutMediator(tabLayout, viewPager) { tab, position ->
            tab.text = "OBJECT ${(position + 1)}"
        }.attach()
    }
    ...
}

Java

public class CollectionDemoFragment extends Fragment {
    ...
    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        TabLayout tabLayout = view.findViewById(R.id.tab_layout);
        new TabLayoutMediator(tabLayout, viewPager,
                (tab, position) -> tab.setText("OBJECT " + (position + 1))
        ).attach();
    }
    ...
}

如需分頁版面配置的其他設計指南,請參閱「分頁質感設計說明文件」

其他資源

如要進一步瞭解 ViewPager2,請參閱下列其他資源:

範例

影片