Develop Reference

Blank fragment after navigation with BottomNav and TabMenu

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:
When I open the app
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.

The answer to my problem was to use a child-parent relation between the different fragments. With the click on BottomNav#1 I am inflating an fragment which inflates a new fragment inside itself. That was the key problem. In my code I handled this as a second "normal" getFragmentManager();.
The answer is to use getChildFragmentManager(); for the nested fragment instead. Like this:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{
rootView= inflater.inflate(R.layout.fragment_ausweis, container, false);
tabLayout1 = rootView.findViewById(R.id.tablayoutAusweis);
viewPager = rootView.findViewById(R.id.viewPagerAusweis);
ausweisPageAdapter = new AusweisPageAdapter(getChildFragmentManager(), tabLayout1.getTabCount());
viewPager.setAdapter(ausweisPageAdapter);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout1));
...
...
Hopefuly this will help some people when they face the same problem with nested fragments.

AppIntro Android Library. How can i use fragments with its xml and .java?

AppIntro is an Android Library that helps you make a cool intro for your app.
AppIntro Library
// Add your slide's fragments here
// AppIntro will automatically generate the dots indicator and buttons.
addSlide(first_fragment);
addSlide(second_fragment);
addSlide(third_fragment);
addSlide(fourth_fragment);
But when I try to attach a fragment created by me, I get an error.
And this is the error:
How can i do to add my fragment1?

While addSlide() method needs android.supportv4.app.Fragment as parameter, so your custom Fragment1 should extend from android.supportv4.app.Fragment class.

1、
import android.support.v4.app.Fragment;
2、
public class Slide_First extends Fragment {
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.slide_first, null);
return view;
}
}

first: create your fragments like always and add the xml elements you need to it, and in your activity just do this
Edit: It is not necessary to extend to AppIntro or AppIntro2
public class MyIntro extends AppIntro2 implements ISlidePolicy {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate (savedInstanceState);
Intro1 fragment1 = new Intro1 ();
Intro2 fragment2 = new Intro2 ();
Intro3 fragment3 = new Intro3 ();
addSlide (fragment1);
addSlide (fragment2);
addSlide (fragment3);
//Only personalization
showStatusBar (false);
showSkipButton (false);
setFadeAnimation ();
setBarColor (Color.TRANSPARENT);
}
}
Edit2: import these dependences in your fragment
import android.support.v4.app.Fragment;
import android.support.v7.app.AppCompatActivity;

Adding extended fragment to Activity

I have been trying to build a Master-Detail f low in android but wanted to change one of the detail fragments to a different fragment. As this is one of my first Android applications, I was just trying to make a picture appear on this new fragment. For this, I built the following two classes
1) Fragment class ( displays the picture to be displayed )
package com.userName.miscapp;
import com.userName.miscapp.dummy.DummyContent;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class PictureFragment extends Fragment {
// Default Copy Constructor for the fragment
public PictureFragment() {
}
#Override
public void onCreate ( Bundle savedInstanceState )
{
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView ( LayoutInflater inflater , ViewGroup container , Bundle savedInstanceState )
{
View rootView = inflater.inflate(R.layout.fragment_simple_picture, container, false);
return rootView;
}
}
2) Activity to display the same
package com.userName.miscapp;
import android.os.Bundle;
import android.app.Activity;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.view.Menu;
public class SimplePicture extends FragmentActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getActionBar().setDisplayHomeAsUpEnabled(true);
if (savedInstanceState == null) {
// Create the detail fragment and add it to the activity
// using a fragment transaction.
Bundle arguments = new Bundle();
arguments.putString(ItemDetailFragment.ARG_ITEM_ID,
getIntent().getStringExtra(ItemDetailFragment.ARG_ITEM_ID));
PictureFragment frag = new PictureFragment();
frag.setArguments(arguments);
android.support.v4.app.FragmentManager fragmentManager = getSupportFragmentManager();
android.support.v4.app.FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.add(R.id.simple_picture_container,frag).commit();
//setContentView(R.layout.activity_simple_picture);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.simple_picture, menu);
return true;
}
}
On compilation, it does not recognize the PictureFragment to be an extension of Fragment class. This is inspite of it being clearly written in the first file. Searching for solutions on Stackoverflow said to extend FragmentActivity instead of Activity and trying to use getSupportFragmentManager() neither of which helped.
PS : Using 11 as the base for the current application.
Any help would be appreciated
Thanks

This is because you are using android.app.Fragment from new API in conjunction with android.support.v4.app.FragmentManager from support library, you should replace import in your PictureFragment from android.app.Fragment to android.support.v4.app.Fragment to make it work.

Android using intent to open a fragment from an activity

I am implementing an app which has a gridview of images in one activity and one fragment for each image which contains the image in full screen. When i click on any of the images in the grid, it should open up the corresponding fragment. However, we cannot use intent to do this.
here is my code
public void onItemClick(AdapterView<?> arg0, View arg1, int position,
long arg3) {
// TODO Auto-generated method stub
if(position==0)
{
Intent i=new Intent(Gallery.this,ImageFrag1.class);
startActivity(i);
}
and the fragment is
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class ImageFrag1 extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.imagefrag1, container, false);
}
}
This fragment is bound to an activity ImagesSwipe. SO how do i achieve the transition between grid view item and its corresponding fragment.
Thanks

You don't need one Fragment for one Image. Just reuse one Fragment with an ImageView in it's layout for every Image.
Fragments aren't invoked like Activities through an Intent. They can only exist as part off an Activity, that is what they are designed for. Think about them as a reusable UI-Modul for an Activity. To add a Fragment to an Activity you have to use the FragmentManager and the FragmentTransaction classes, which provide all interactions with Fragments.
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.add(YourFragment.newInstance(), null);
ft.commit();
Have a look at this guide from the Google Docs where the basic things about GridViews are described. In Addition you should read about Fragments. And here is a Tutorial about your approach.

You may want to check out DialogFrament, here is an example.
Instead of using intent you use FramentManager:
if(position==0)
{
FragmentManager fm = getFragmentManager();
ImageFrag1 imageDialog = new ImageFrag1()
ImageFrag1.show(fm, "image_title");
}
And your dialogFrament becomes:
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class ImageFrag1 extends DialogFragment {
public ImageFrag1() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.dialog_fragment, container, false);
}
}

Can a fragment extend a fragment activity? [Android]

I have created a MainActivity which consists of 3 tabs which are scrollable (by using ViewPager). Now each of these 3 tabs is a Fragment. Also, I am using ActionBarSherlock (ABS).
For the 1st Fragment, I have created the following class:
public class Fragment_1 extends SherlockFragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
View v = inflater.inflate(R.layout.fragment1, container, false);
return v;
/* R.layout.fragment1 only contains a TextView. */
}
}
For the 2nd Fragment, I want to extend a FragmentActivity as shown below.
public class Fragment_2 extends FragmentActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment2);
}
}
The 3rd Fragment is same as the first one.
But when I launch the app, it crashes. So, am I wrong in extending FragmentActivity for the class Fragment_2? Is it illegal to extend a FragmentActivity or even an Activity to fragment classes? If not, what is the problem here?
Thanks.
EDIT: After #CommonsWare's answer I updated my class as follows:
public class Fragment_2 extends SherlockFragment {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Button send = (Button) findViewById(R.id.bSend); //Error at this line
//some error free code
FragmentTransaction t = getSupportFragmentManager().beginTransaction(); //Error at this line
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
View v = inflater.inflate(R.layout.fragment2, container, false);
return v;
}
My final two questions are:
How should I access my R.id.bSend Button in the Fragment_2 class.
Eclipse is giving the suggestion to change getSupportFragmentManager() to getFragmentManager(). Is that change all right?
Thanks!

Is it illegal to extend a FragmentActivity or even an Activity to fragment classes?
Fragment is a Java class. Your fragment implementations (for use as pages in your ViewPager) must inherit from Fragment, directly or indirectly.
Activity does not inherit from Fragment. FragmentActivity does not inherit from Fragment. Hence, you cannot inherit from Activity or FragmentActivity and somehow also inherit from Fragment.