我有一个带有三个选项卡的底部导航(主页,仪表板,通知).每个底部导航选项卡都是一个片段.第一个标签即.主片段包含另外的顶部导航标签,其具有四个标签(标签1,标签2,标签3,标签4).
问题
>当我直接从“主页”选项卡导航到“通知”选项卡并返回“主页”选项卡时,Tab1 /选择了之前选择的选项卡(顶部导航选项卡),未加载选项卡的内容.
>当我从选项卡1(主页片段选项卡)一直滑动选项卡到通知选项卡并向后滑动时,在到达选项卡4时,未加载选项卡的内容,并且首先从选项卡4滑动到选项卡3,滑动执行没有拿到标签3.标签指示器只需移动一点,然后在第二次滑动时按预期方式转到标签3.
该应用程序包含大量代码,因此我只需将完整代码链接到Github.
MainActivity.java
public class MainActivity extends AppCompatActivity {
private ViewPager viewPager;
NavigationView navigationView;
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.navigation_home:
viewPager.setCurrentItem(0);
return true;
case R.id.navigation_dashboard:
viewPager.setCurrentItem(1);
return true;
case R.id.navigation_notifications:
viewPager.setCurrentItem(2);
return true;
}
return false;
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Hide the activity toolbar
getSupportActionBar().hide();
//Initializing viewPager
viewPager = (ViewPager) findViewById(R.id.viewpager);
setupViewPager(viewPager);
final BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position,float positionOffset,int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
switch (position){
case 0:
navigation.setSelectedItemId(R.id.navigation_home);
break;
case 1:
navigation.setSelectedItemId(R.id.navigation_dashboard);
break;
case 2:
navigation.setSelectedItemId(R.id.navigation_notifications);
break;
}
}
@Override
public void onPageScrollStateChanged(int state) {
}
});
}
private void setupViewPager(ViewPager viewPager) {
BottomNavPagerAdapter adapter = new BottomNavPagerAdapter(getSupportFragmentManager());
adapter.addFragment(new FirstFragment());
adapter.addFragment(new SecondFragment());
adapter.addFragment(new ThirdFragment());
viewPager.setAdapter(adapter);
}
}
FirstFragment.java(主页)
public class FirstFragment extends Fragment {
private TabLayout tabLayout;
private ViewPager firstViewPager;
public FirstFragment() {
// required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater,ViewGroup container,Bundle savedInstanceState) {
// Inflate the layout for this fragment
View rootView = inflater.inflate(R.layout.fragment_first,container,false);
firstViewPager = (ViewPager) rootView.findViewById(R.id.viewpager_content);
tabLayout = (TabLayout) rootView.findViewById(R.id.tabs);
tabLayout.setupWithViewPager(firstViewPager);
setupViewPager(firstViewPager);
return rootView;
}
private void setupViewPager(ViewPager viewPager) {
TabViewPagerAdapter adapter = new TabViewPagerAdapter(getActivity().getSupportFragmentManager());
adapter.addFragment(new Tab1Fragment(),"Tab 1");
adapter.addFragment(new Tab1Fragment(),"Tab 2");
adapter.addFragment(new Tab1Fragment(),"Tab 3");
adapter.addFragment(new Tab1Fragment(),"Tab 4");
viewPager.setAdapter(adapter);
}
}
问题
解决方法
实际上,这是一个常见的错误 – 你在片段中使用Activity的FragmentManager,但由于这个片段包含另一个子片段,你必须使用片段本身的FragmentManager.所以修复很简单 – 你只需要在你的片段中更改getActivity().getSupportFragmentManager()到getChildFragmentManager(),所以代码将是：
private void setupViewPager(ViewPager viewPager) {
TabViewPagerAdapter adapter = new TabViewPagerAdapter(getChildFragmentManager());
...
...
viewPager.setAdapter(adapter);
}
这应该按预期工作.
