选择特定选项卡上的打开活动

Question

我想实施Tablayout addOnTabSelectedListener以在特定标签点击上打开新活动。有3个选项卡，目前它们与片段连接。我想点击位置1标签时启动一个活动。我可以在onTabSelected中执行此操作，但在打开活动之前，它会显示附加到同一位置的片段。如何删除该片段？

public class MainActivity extends AppCompatActivity {

    private TabLayout tabs;
    private ViewPager viewpager;

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


        tabs = (TabLayout)findViewById(R.id.tabs);
        viewpager = (ViewPager)findViewById(R.id.viewpager);
        setupViewPager(viewpager);


        tabs.addTab(tabs.newTab());
        tabs.addTab(tabs.newTab());
        tabs.addTab(tabs.newTab());

        tabs.setupWithViewPager(viewpager);

        tabs.addOnTabSelectedListener(onTabSelectedListener(viewpager));

    }

    private TabLayout.OnTabSelectedListener onTabSelectedListener(final ViewPager viewPager) {

        return new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                viewPager.setCurrentItem(tab.getPosition());
            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab) {

            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {

            }
        };
    }

    private void setupViewPager(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        adapter.addFragment(new Frag1(), "ONE");
        adapter.addFragment(new Frag2(), "TWO");
        adapter.addFragment(new Frag3(), "THREE");
        viewPager.setAdapter(adapter);
        viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabs));
        onTabSelectedListener(viewPager);
    }

    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);
        }
    }
}


    private TabLayout.OnTabSelectedListener onTabSelectedListener(final ViewPager viewPager) {

        return new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                viewPager.setCurrentItem(tab.getPosition());
            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab) {

            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {

            }
        };
    }

    private void setupViewPager(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        adapter.addFragment(new Frag1(), "ONE");
        adapter.addFragment(new Frag2(), "TWO");
        adapter.addFragment(new Frag3(), "THREE");
        viewPager.setAdapter(adapter);
        viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabs));
        onTabSelectedListener(viewPager);
    }

    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

试试这个：

使用FragmentStatePagerAdapter，原因是FragmentPagerAdapter会将所有加载到视图中的视图永久保存到内存中。 FragmentStatePagerAdapter处置超出当前

的视图的位置

还覆盖适配器方法getItemPosition

例如：

    private class ViewPagerAdapter extends FragmentStatePagerAdapter {

    //... your existing code

    @Override
    public int getItemPosition(Object object){
        return PagerAdapter.POSITION_NONE;
    }

}

source

它会每次重新创建你的片段，而不是先从内存中加载它们。

要开始活动，请在您的特定片段onCreate()

中执行此操作

希望这会有所帮助..

Answer 2

我有同样的要求，我做的是使用RelativeLayout＆amp; amp;重叠TabLayout中心的textview。在textview上应用click事件。我无法发布我的布局请参考演示图片