如何 return 来自 FragmentPagerAdapter 的多个片段

Question

如果我将 TabLayout 与 FragmentPagerAdapter 一起使用，覆盖的函数 getItem(int position) 只是 return 一个片段。如果屏幕较大，我希望有 2 个片段 returned。我该怎么做？应该将这 2 个片段包装成一个片段并改用它还是有更好的解决方案？

FragmentPagerAdapter:

public class SectionsPagerAdapter extends FragmentPagerAdapter {

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

    @Override
    public Fragment getItem(int position) {
        switch (position) {
            case 0: //Ingredients
                return IngredientsFragment.newInstance(mRecipe);
            case 1: // Details
            {
                // TODO Here instead of DetailFragment I want to return
                // two fragments called DetailFragment and StepFragment.
                return DetailFragment.newInstance(mRecipe);
            }
            default:
                throw new RuntimeException(this.toString() + " Wrong fragment!");
        }
    }

然后在我的 Activity onCreate:

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        // Initializing, etc.

        mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
        mViewPager.setAdapter(mSectionsPagerAdapter);

        TabLayout tabLayout = findViewById(R.id.tabs);
        mViewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
        tabLayout.addOnTabSelectedListener(new TabLayout.ViewPagerOnTabSelectedListener(mViewPager));
    }

Answer 1

我看不出你在这里有多少回旋余地。

这两个选项是排他性的：

您将返回一个包含两个嵌套片段（包裹片段）的片段
您将返回两个片段，每个片段都锚定到他自己的选项卡。

如果你想让两个片段出现在ViewPager的单个页面上，你别无选择，只能将它们包裹起来。否则滑动会在这两个片段之间，这就像它们完全不同一样，是不相关的。

Answer 2

好的，我设法使用 Fragment 解决了这个问题，该问题由另外两个子片段组成。只是不要忘记在这种情况下 FragmentManager 对象应该填充 getChildFragmentManager() 才能正常工作。有关详细信息，请查看我的 BakingApp 项目 DetailStepWideScreenFragment.java

GitHub Repos

片段包装器：

public class DetailStepWideScreenFragment extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_detail_step_wide_screen, container, false);

        // I added the fragments here. StepFragment can be replaced using
        // replaceStepFragment function.
        DetailFragment detailFragment = DetailFragment.newInstance(mRecipe);
        StepFragment stepFragment = StepFragment.newInstance(mRecipe, mStepId);
        FragmentTransaction transaction = getChildFragmentManager().beginTransaction();
        transaction.add(R.id.fl_detail_fragment_wide_screen, detailFragment);
        transaction.add(R.id.fl_step_fragment_wide_screen, stepFragment);
        transaction.commit();

        return view;
    }

    public void replaceStepFragment(String stepId) {
        mStepId = stepId;
        FragmentTransaction transaction = getChildFragmentManager().beginTransaction();
        StepFragment stepFragment = StepFragment.newInstance(mRecipe, mStepId);
        transaction.replace(R.id.fl_step_fragment_wide_screen, stepFragment);
        transaction.commit();
    }
}

PagerAdapter:

public class SectionsPagerAdapter extends FragmentPagerAdapter {
    private DetailStepWideScreenFragment currentFragment;

    public SectionsPagerAdapter(FragmentManager fm) {
        super(fm);
        currentFragment = null;
    }

    @Override
    public Fragment getItem(int position) {
        switch (position) {
            case 0: //Ingredients
                return IngredientsFragment.newInstance(mRecipe);
            case 1: // Details
            {
                // Show base on screen size.
                if (mIsLargeScreen) {
                    DetailStepWideScreenFragment detailStepWideScreenFragment = DetailStepWideScreenFragment.newInstance(mRecipe, "0");
                    currentFragment = detailStepWideScreenFragment;
                    return detailStepWideScreenFragment;
                } else {
                    return DetailFragment.newInstance(mRecipe);
                }
            }
            default:
                throw new RuntimeException(this.toString() + " Wrong fragment!");
        }
    }

    @Override
    public int getCount() { return 2; }

    public DetailStepWideScreenFragment getCurrentFragment() {
        return currentFragment;
    }

}

如何 return 来自 FragmentPagerAdapter 的多个片段

How to return multiple fragments from FragmentPagerAdapter

android

android-fragments

android-tablayout

fragmentpageradapter