I am developing an Android app that has a little bit confusing navigation structure which leads me to my problem. There are two ways to navigate through the app. First is the BottomNav and second is a TabMenu. I thought about working with fragments that replace each other, so I came up with the following structure:
1. BottomNav#1
- TabMenu#1
- Tabmenu#2
- TabMenu#3
- ...
2. BottomNav#2
- TabMenu#4
- Tabmenu#5
- TabMenu#6
- ...
... and so on.
The problem I am facing is that when I navigate from BottomNav#1 to BottomNav#2 and back again there is a blank screen that doesn't show the content of the actual fragment:
After clicking on BottomNav#2 and then back to BottomNav#1 the fragment seems to be blank
My guess is that I somehow have a problem with my fragmentTransaction.replace(); as it seems like the fragment doesn't get loaded again? I am kind of new to this and really tried to find an answer online but this is a bit specific why I guess I didn't find anything.
This is my MainActivity:
package com.example.XXXX;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomNavigationView;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.view.MenuItem;
import android.widget.FrameLayout;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
private FrameLayout mMainFrame;
private AusweisFragment ausweisFragment;
private SpendenFragment spendenFragment;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ausweisFragment = new AusweisFragment();
spendenFragment = new SpendenFragment();
BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
}
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener()
{
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item)
{
switch (item.getItemId())
{
case R.id.navigation_ausweis:
setFragment(ausweisFragment);
return true;
case R.id.navigation_spenden:
setFragment(spendenFragment);
return true;
}
return false;
}
};
private void setFragment(Fragment fragment)
{
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.main_frame, fragment);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
}
This should lead to e.g. the fragment called "ausweis" by clicking on on BottomNav#1 (switch case):
package com.example.XXXXXXX;
import android.app.Activity;
import android.os.Bundle;
import android.support.design.widget.TabItem;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class AusweisFragment extends Fragment {
private View rootView;
private AusweisPageAdapter ausweisPageAdapter;
private TabLayout tabLayout;
private ViewPager viewPager;
public AusweisFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{
rootView= inflater.inflate(R.layout.fragment_ausweis, container, false);
tabLayout = rootView.findViewById(R.id.tablayoutAusweis);
viewPager = rootView.findViewById(R.id.viewPagerAusweis);
ausweisPageAdapter = new AusweisPageAdapter(getActivity().getSupportFragmentManager(), tabLayout.getTabCount());
viewPager.setAdapter(ausweisPageAdapter);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.addOnTabSelectedListener(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) {
}
});
return rootView;
}
}
After that I would like to call another fragment called "spenden" which is exactly the same as the fragment called "ausweis" but with different named tabs, so I think it is not bother you with more code.
edit: I missed about writing where the "content" I wrote about gets from. For a first try and proof that the fragments change, I hardcoded a phrase like "Ausweis" into the XML which is connected to my fragment java class.
Maybe one of you has an idea to that problem. I think it has something to do with my onCreateView in one of the fragments, but I have no close clue.
Hopefuly I didn't miss an important detail. I am very grateful for any kind of help. Thanks a lot in advance.
