底部导航片段内的多个 Tab 片段 [英] Multiple Tab fragments inside bottom navigation fragment
问题描述
在带有三个选项卡(主页、仪表板、通知)的底部导航中.每个底部导航选项卡都是一个片段.第一个标签，即.主页片段包含另一个具有四个选项卡(Tab 1、Tab 2、Tab 3、Tab 4)的顶部导航选项卡.
In bottom navigation with three tabs (Home, Dashboard, Notifications). Each bottom navigation tab is a fragment. The first tab ie. Home fragment contains another top navigation tabs having four tabs (Tab 1, Tab 2, Tab 3, Tab 4).
问题
当从 首页 标签直接导航到 通知 标签并返回 首页 标签时，Tab1/之前选择的标签选项卡(顶部导航选项卡)选项卡的内容未加载.
When navigate from Home tab to Notifications tab directly and come back to Home tab, Tab1/which ever tab previously selected tab (top navigation tabs) the content of the tab is not loaded.
当从 Tab 1(主页片段标签)一直滑动到 Notification 标签并向后滑动时，到达 Tab 4 选项卡的内容未加载第一次从 Tab 4 滑动到 Tab 3 时不会滑动到 Tab 3.标签指示器只是移动了一点，第二次滑动时它会按预期转到标签 3.
When swipe the tabs from Tab 1 (Home fragment tab) all the way to Notification tab and swipe back, on reaching the Tab 4 the content of the tab is not loaded and on first swipe from Tab 4 to Tab 3 the swipe does not take to Tab 3. The tab indicator just move a little and on second swipe it goes to Tab 3 as expected.
该应用程序包含大量代码，因此我将完整代码链接到 Github.
The app contains a lot of code so I'll just link the full code to Github.
这里是我的代码供快速参考
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)
FirstFragment.java (Home)
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
- 代码有什么问题?
- 如何解决这个问题?(布局是必需的)或者有没有更好的方法来从屏幕截图中提出布局?
推荐答案
其实这是一个常见的错误——你在fragment里面使用了Activity的FragmentManager，但由于此片段包含另一个 child 片段，因此您必须使用片段本身的 FragmentManager.所以修复很简单 - 您只需在片段中将 getActivity().getSupportFragmentManager() 更改为 getChildFragmentManager() ，因此代码将是:
Actually, it is a common mistake - you're using FragmentManager of your Activity inside the fragment, but since this fragment contains another child fragments you have to use FragmentManager of the fragment itself. So the fix is simple - you just have to change getActivity().getSupportFragmentManager() to getChildFragmentManager() inside your fragments, so the code will be:
private void setupViewPager(ViewPager viewPager) {
TabViewPagerAdapter adapter = new TabViewPagerAdapter(getChildFragmentManager());
...
...
viewPager.setAdapter(adapter);
}
这应该可以按预期工作.
And this should work as expected.
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