只有在选定时才在ViewPager中加载片段

Question

我怎么能那么做？我也不知道。我在等你的帮助。谢谢。

我的代码：

public class Fragments extends AppCompatActivity {

    private TabLayout tabLayout;
    private ViewPager viewPager;

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

        viewPager = (ViewPager) findViewById(R.id.viewpager);
        setupViewPager(viewPager);

        tabLayout = (TabLayout) findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(viewPager);
    }

    private void setupViewPager(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        adapter.addFragment(new FirstFragment(), "1");
        adapter.addFragment(new SecondFragment(), "2");
        adapter.addFragment(new ThirdFragment(), "3");
        viewPager.setAdapter(adapter);
    }

    class ViewPagerAdapter extends FragmentPagerAdapter {
        private final List<Fragment> mFragmentList = new ArrayList<>();
        private final List<String> mFragmentTitleList = new ArrayList<>();

        public ViewPagerAdapter(FragmentManager manager) {
            super(manager);
        }

        @Override
        public Fragment getItem(int position) {
            return mFragmentList.get(position);
        }

        @Override
        public int getCount() {
            return mFragmentList.size();
        }

        public void addFragment(Fragment fragment, String title) {
            mFragmentList.add(fragment);
            mFragmentTitleList.add(title);
        }

        @Override
        public CharSequence getPageTitle(int position) {
            return mFragmentTitleList.get(position);
        }
    }
}

Answer 1

如果没有人给你一个好的答案，我知道这是5年后，但任何人读这。我实际上有相反的问题。我需要同时加载所有选项卡。现在发生在我身上的是一次只加载一个标签。我需要将此适配器用于带tablayout的viewpager2，这样我就可以禁用viewpager从左向右滑动以满足我的特定用途。

下面是我的代码：

警告代码使用KOTLIN而不是JAVA

class RecipeTabAdapter internal constructor(fm: FragmentManager, lifecycle: Lifecycle) : FragmentStateAdapter(fm, lifecycle) {

val fragmentsList: ArrayList<Fragment> = arrayListOf()

fun addFragment(fragment: Fragment) {
    fragmentsList.add(fragment)
}

override fun getItemCount(): Int {
    return fragmentsList.size
}

override fun createFragment(position: Int): Fragment {
    when (position) {
        position -> fragmentsList[position]
        position -> fragmentsList[position]
    }
    return fragmentsList[position]
}