android - 选项卡不显示

Question

我想在 myActivity 中添加选项卡，当我单击某些选项卡时，会创建并添加 fragment 。但现在当我单击选项卡时，什么也没有发生。 选项卡 Activity :

public class TabsActivity extends FragmentActivity {

    Fragment directFragmentTab = new Direct();
    Fragment adventuresFragmentTab = new AdventuresFragment();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.tabs_activity);


        TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
        tabLayout.addTab(tabLayout.newTab().setText("Tab 1"));
        tabLayout.addTab(tabLayout.newTab().setText("Tab 2"));

        tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
        FragmentManager fragmentManager = getSupportFragmentManager();
        final ViewPager viewPager = (ViewPager) findViewById(R.id.pager);
        final ViewPagerAdapter adapter = new ViewPagerAdapter(fragmentManager, tabLayout.getTabCount())
                 {
            @Override
            public int getCount() {
                return 0;
            }

            @Override
            public boolean isViewFromObject(View view, Object object) {
                return false;
            }
        };
        viewPager.setAdapter(adapter);
        viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
        tabLayout.setOnTabSelectedListener(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) {

            }
        });
    }
}

ViewPagerAdapter:

public class ViewPagerAdapter extends FragmentStatePagerAdapter {
    int mNumOfTabs;

    public ViewPagerAdapter(FragmentManager fm, int NumOfTabs) {
        super(fm);
        this.mNumOfTabs = NumOfTabs;
    }


    @Override
    public android.support.v4.app.Fragment getItem(int position) {

        switch (position) {
            case 0:
                Direct tab1 = new Direct();
                return tab1;
            case 1:
                AdventuresFragment tab2 = new AdventuresFragment();
                return tab2;


            default:
                return null;
        }
    }

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

我做错了什么？代码编译没有错误，但我错过了一些逻辑。

Answer 1

您不应进一步覆盖 ViewPagerAdapter 中的方法。就这样

final ViewPagerAdapter adapter = new ViewPagerAdapter(fragmentManager, tabLayout.getTabCount());