Android-尚未显示ViewPager第三选项卡

Question

i有一个包含3个选项卡片段的ViewPager。第一个和第二片效果很好，但是当我扫到第三个选项卡时我看不到他。仅当带有ViewPager的活动重新加载（移动到另一个活动并返回）时，第三个选项卡才显示。

。

我的代码：

    private void setupViewPager(ViewPager viewPager) {
    adapter = new PagerAdapter(getSupportFragmentManager());
    adapter.addFragment(new Fragment1(), Constants.TAB_0);
    adapter.addFragment(new Fragment2(), Constants.TAB_1);
    adapter.addFragment(new Fragment3(), Constants.TAB_2);
    viewPager.setAdapter(adapter);
    viewPager.setOffscreenPageLimit(3);
}

Pager适配器：

public class PagerAdapter extends FragmentPagerAdapter {
/*
 * Arraylist used to contain the fragments
 * and contain fragments title's
 */
private final List<Fragment> fragmentList = new ArrayList<>();
private final List<String> fragmentTitleList = new ArrayList<>();
public PagerAdapter(FragmentManager manager) {
    super(manager);
}
@Override
public Fragment getItem(int position) {
    return fragmentList.get(position);
}
@Override
public int getCount() {
    return fragmentList.size();
}
//Adds the fragment and it's title. Called in MainActivity
public void addFragment(Fragment fragment, String title) {
    fragmentList.add(fragment);
    fragmentTitleList.add(title);
}
//Retrieves the title of the tab
@Override
public CharSequence getPageTitle(int position) {
    return fragmentTitleList.get(position);
}
@Override
public int getItemPosition(Object object) {
    return POSITION_NONE;
}

}

Answer 1

这是我的适配器，在getItem上，我将片段对象设置为片段活动。

public class SectionPagerAdapter extends FragmentPagerAdapter {
    Fragment fragment;
    public SectionPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        if (position == 0){
            fragment = new FragmentOne();
        }
        else if (position == 1){
            fragment = new FragmentTwo();
        }
        else if (position == 2){
            fragment = new FragmentThree();
        }
        return fragment;
    }
    @Override
    public int getCount() {
        return 3;
    }
    @Override
    public CharSequence getPageTitle(int position) {
        switch (position) {
            case 0:
                return "name one";
            case 1:
                return "name two";
            case 2:
                return "name three";
        }
        return null;
    }
}

然后在我的主要活动中，我称其为：

ViewPager viewPager = (ViewPager) findViewById(R.id.view_pager);
SectionPagerAdapter sectionPagerAdapter = new SectionPagerAdapter(getSupportFragmentManager());
mViewPager.setAdapter(sectionPagerAdapter);

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

尝试用上述代码替换代码，让我知道它是否有帮助！

Answer 2

使用 new PagerAdapter(getChildSupportFragmentManager()); 而不是 getSupportFragmentManager()

尝试这个！