为 Fragment 设置标签 - Android (Java) 中的 ViewPager2 和 FragmentStateAdapter

Question

MainActivity.java 中声明 Viewpager2 的代码：

        viewPager = findViewById(R.id.pager);
        tabLayout = findViewById(R.id.tabs);
        tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
        tabLayout.setTabMode(TabLayout.MODE_FIXED);
        pagerAdapter = new ScreenSlidePagerAdapter(MainActivity.this);
        viewPager.setAdapter(pagerAdapter);
        new TabLayoutMediator(tabLayout, viewPager,
                new TabLayoutMediator.TabConfigurationStrategy() {
                    @Override
                    public void onConfigureTab(@NonNull TabLayout.Tab tab, int position) {
                        if (position == 0) {
                            tab.setText("Home");
                        } else if (position == 1) {
                            tab.setText("Stats");
                        } else {
                            tab.setText("Top");
                        }
                    }
                }).attach();
        viewPager.setCurrentItem(0);

ScreenSlidePagerAdapter 中扩展 FragmentStateAdapter 的代码：

public class ScreenSlidePagerAdapter extends FragmentStateAdapter {
    private static final int NUM_PAGES = 3;

    public ScreenSlidePagerAdapter(FragmentActivity fa) {
        super(fa);
    }

    @NonNull
    @Override
    public Fragment createFragment(int position) {
        if (position == 0) {
            return new MyCoinsFragment();
        }else if (position == 1) {
            return new StatsFragment();
        }else {
            return new TopFragment();
        }
    }

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


}

我的片段布局文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout  xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:id="@+id/layoutData"
    android:layout_marginStart="6dp"
    android:layout_marginTop="10dp"
    android:layout_marginEnd="6dp"
    android:layout_marginBottom="10dp"
    android:padding="6dp"
    android:weightSum="1">

    <ImageView
        android:layout_width="0dp"
        android:layout_height="16dp"
        android:layout_gravity="center_vertical"
        android:layout_weight="0.1"/>

    <TextView
        style="@style/subHeadings"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:layout_weight="0.5"
        android:singleLine="true"
        android:text="sadsda" />

    <TextView
        style="@style/subHeadings"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:layout_weight="0.4"
        android:text="17.2 TH/s"
        android:textAlignment="textEnd" />
</LinearLayout>

我需要以编程方式为片段设置标签。将不胜感激一些帮助在哪个方向进入。我知道它将在 Fragment State Adapter 中完成，我需要在其中设置标签，但不确定如何？

Answer 1

你可以像这样在适配器中设置标签

public class HomePageAdapter extends FragmentStatePagerAdapter {
    int mNumOfTabs;

    public HomePageAdapter(FragmentManager fm, int NumOfTabs) {
        super(fm);
        this.mNumOfTabs = NumOfTabs;
    }

    @Override
    public Fragment getItem(int position) {

        switch (position) {
            case 0:
                MyFragment myFragment = new MyFragment();
                myFragment.setTag("tag");
                return myFragment;
            case 1:
                MyFragment1 myFragment1 = new MyFragment1();
                myFragment1.setTag("tag1");
                return myFragment1;
            default:
                return null;
        }
    }

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

然后你可以得到标签：

List fragments = getSupportFragmentManager().getFragments();
Fragment disFrag = null;
for (int i = 0; i < fragments.size(); i++) {
    if (((Fragment) fragments.get(i)).getTag() == "tag")
        disFrag = (Fragment) fragments.get(i);
}