android - 如何在同时显示多个 fragment 的同时在viewpager中查找当前可见的 fragment

我正在构建一个使用ViewPager和FragmentStatePagerAdapter一次显示多个片段的应用程序。以下是我在做什么：

public class PageViewActivity extends FragmentActivity {
    protected static final String TAG = "PageViewActivity";
    MyPageAdapter pageAdapter;
    private List<Fragment> fragments;
    private FragmentManager fragmentManager;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_page_view);

        fragments = getFragments();

        fragmentManager = getSupportFragmentManager();

        pageAdapter = new MyPageAdapter(fragmentManager, fragments);

        ViewPager pager = (ViewPager) findViewById(R.id.viewpager);
        pager.setAdapter(pageAdapter);
        pager.setOnPageChangeListener(new OnPageChangeListener() {

            @Override
            public void onPageSelected(int position) {
                Log.i(TAG, "Inside onPageSelected....................... "
                        + position);
                ((MyFragment) pageAdapter.getChildAt(position)).updateView();
            }

            @Override
            public void onPageScrolled(int arg0, float arg1, int arg2) {
                Log.i(TAG, "Inside onPageScrolled... " + arg0);
            }

            @Override
            public void onPageScrollStateChanged(int arg0) {
                Log.i(TAG, "Inside onPageScrollStateChanged... " + arg0);
            }
        });
    }

    private List<Fragment> getFragments() {
        List<Fragment> fList = new ArrayList<Fragment>();

        fList.add(MyFragment.newInstance("Fragment 1"));
        fList.add(MyFragment.newInstance("Fragment 2"));
        fList.add(MyFragment.newInstance("Fragment 3"));
        fList.add(MyFragment.newInstance("Fragment 4"));
        fList.add(MyFragment.newInstance("Fragment 5"));
        fList.add(MyFragment.newInstance("Fragment 6"));
        fList.add(MyFragment.newInstance("Fragment 7"));

        return fList;
    }

    private class MyPageAdapter extends FragmentStatePagerAdapter {
        private List<Fragment> fragments;

        public MyPageAdapter(FragmentManager fm, List<Fragment> fragments) {
            super(fm);
            this.fragments = fragments;
        }

        public void setList(List<Fragment> fragments) {
            this.fragments = fragments;
            notifyDataSetChanged();
        }

        @Override
        public Fragment getItem(int position) {
            Log.i(TAG, "Inside getItem............");
            return this.fragments.get(position);
        }

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

        @Override
        public float getPageWidth(int position) {
            if (position == 0) {
                return 0.4f;
            } else {
                return 0.3f;
            }
        }

        public Fragment getChildAt(int position) {
            return this.fragments.get(position);
        }

        @Override
        public int getItemPosition(Object object) {
            Log.i(TAG, "getItemPosition..........");
            if (fragments.contains(object)) {
                Log.i(TAG,
                        "fragmentList.contains(object)... " + object.toString());
                return POSITION_UNCHANGED;
            }
            return POSITION_NONE;
        }

                    }
    }
}

我的问题是如何找到可见的碎片？ （例如，屏幕截图中的片段1、2和3）

我知道abot pager.setOnPageChangeListener和Fragment.setUserVisibleHint（boolean isVisibleToUser）但对我没有用:-(

非常感谢您的帮助。谢谢！！！

最佳答案

这个link可能会有所帮助

使用这一行代码
Fragment fr = getSupportFragmentManager().findFragmentByTag(“android:switcher:” + R.id.pager + “:” + mViewPager.getCurrentItem());