Develop Reference

How to make a transition from one fragment to another? [duplicate]

I am currently trying to create an app having a splash screen, a login screen and a register screen.
The only way to achieve exactly what I need is through fragments. Though when I try to transition from the splash screen to the login fragment the text view which was part of the splash screen remains. The same happens after transitioning from the login fragment to the register fragment as well as from the register fragment back to the login fragment. It is important to note that there is no issue during transitioning between login and register or between register and login - except the fact that the edit text stays there.
My MainActivity.java
public class StartActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_start);
}
#Override
public void onBackPressed(){
Toast.makeText(getApplicationContext(), "Back button is disabled", Toast.LENGTH_SHORT).show();
}
}
My layout for MainActivity
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".StartActivity"
android:background="#mipmap/background">
<fragment
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/viewpagerstart"
android:layout_centerInParent="true"
android:name="com.example.distributedsystemsui.SplashFragment">
</fragment>
</RelativeLayout>
The SplashScreen.java
public class SplashFragment extends Fragment {
LinearLayout linearLayout;
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_splash, container, false);
linearLayout = (LinearLayout) view.findViewById(R.id.f_linearsplash);
Animation animation_fadein = AnimationUtils.loadAnimation((StartActivity)getActivity(), R.anim.fade_in);
linearLayout.startAnimation(animation_fadein);
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
public void run() {
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.setCustomAnimations(R.anim.slide_enter_left, R.anim.slide_exit_left,
R.anim.slide_enter_right, R.anim.slide_exit_right);
LoginFragment loginFragment = LoginFragment.newInstance();
ft.replace(R.id.viewpagerstart, loginFragment);
ft.commit();
}
}, 3000);
return view;
}
}
And the layout for the SplashScreen fragment.
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".LoginFragment"
android:background="#color/Tranparent"
android:id="#+id/frame_splash">
<LinearLayout
android:id="#+id/f_linearsplash"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<ImageView
android:id="#+id/f_splashlogo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_marginTop="70dp"
android:background="#FFFFFF"/>
<TextView
android:id="#+id/f_splashtext"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/app_name"
android:layout_gravity="center_horizontal"
android:layout_marginTop="100dp"
android:background="#FFFFFF"/>
</LinearLayout>
</FrameLayout>
All my search led back to nothing.
I can only assume that either the below contained in the MainActivity.xml creates a confusion (which I tried to change but no luck):
android:name="com.example.distributedsystemsui.SplashFragment"
or that I am doing a mistake in the SplashScreen.java that I cannot locate, even though I tried for more than 5 hours to make it work.

The problem is that you cannot replace fragments added via the <fragment> tag.
Instead, you should either:
1) Switch to FragmentContainerView, which was added in Fragment 1.2.0. It does not suffer from the same issue as the <fragment> tag and lets you do replace operations without issues:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".StartActivity"
android:background="#mipmap/background">
<androidx.fragment.app.FragmentContainerView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/viewpagerstart"
android:layout_centerInParent="true"
android:name="com.example.distributedsystemsui.SplashFragment">
</androidx.fragment.app.FragmentContainerView>
</RelativeLayout>
2) Use a FrameLayout in your layout and manually add the SplashFragment in your activity (this is essentially what FragmentContainerView does for you):
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".StartActivity"
android:background="#mipmap/background">
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/viewpagerstart"
android:layout_centerInParent="true">
</FrameLayout>
</RelativeLayout>
which means you need to add the SplashFragment manually:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_start);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.viewpagerstart, new SplashFragment())
.commit()
}
}

I think it is better to do the fragment transactions from your activity instead of doing it from your fragment. You might consider having functions in your MainActivity as follows.
public class StartActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_start);
}
public void goToLoginFragment() {
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.setCustomAnimations(R.anim.slide_enter_left, R.anim.slide_exit_left,
R.anim.slide_enter_right, R.anim.slide_exit_right);
LoginFragment loginFragment = LoginFragment.newInstance();
ft.replace(R.id.viewpagerstart, loginFragment);
ft.commit();
}
public void goToRegisterFragment() {
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.setCustomAnimations(R.anim.slide_enter_left, R.anim.slide_exit_left,
R.anim.slide_enter_right, R.anim.slide_exit_right);
LoginFragment registerFragment = RegisterFragment.newInstance();
ft.replace(R.id.viewpagerstart, registerFragment);
ft.commit();
}
#Override
public void onBackPressed(){
Toast.makeText(getApplicationContext(), "Back button is disabled", Toast.LENGTH_SHORT).show();
}
}
And then from your SplashFragment call the function that is defined in your activity.
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
public void run() {
((MainActivity) getActivity()).goToLoginFragment();
}
}, 3000);
I hope that solves the problem.

How to show fragment only when button pressed?

I'm trying to show an image below a button only after the button has been pressed. My problem is that the fragment is shown immediately when the app is started and not only after the button has been pressed.
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void say_hello(View view){
Fragment fragment = new ExampleFragment();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.fragment2, fragment).commit();
}
}
public class ExampleFragment extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.news_articles, container, false);
}
}
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:tools="http://schemas.android.com/tools"
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:orientation="vertical"
android:layout_height="fill_parent"
tools:context=".MainActivity">
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal|center_vertical"
android:text="PRESS THIS"
android:id = "#+id/test_button"
android:background="#drawable/test_button"
android:onClick="say_hello"
/>
<fragment
android:id="#+id/fragment2"
android:name="com.example.tic_tac_toe.ExampleFragment"
android:layout_width="match_parent"
android:layout_height="643dp" />
</LinearLayout>
<ImageView
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:src="#drawable/cool_dog">
</ImageView>
I'm guessing the fragment shows up when the app is started because of the name I give to the fragment in the XML, but the fragment needs a name otherwise I only get error. How do I get the fragment to display nothing before I have clicked the button?

Instead of using <fragment /> view in your xml, you can use Framelayout and add your fragment to this Framelayout on button click using the following code -
FragmentTransaction transaction = getFragmentManager().beginTransaction();
transaction.add(R.id.mainframe, fragment);
transaction.commit();
Where mainframe is the id of Framelayout.

You can try doing this
android.app.Fragment fragment = getActivity().getFragmentManager().findFragmentByTag("YOUR_FRAGMENT_TAG");
getActivity().getFragmentManager().beginTransaction().hide(fragment);
inside your click event.

Fragments : unable to start activity Component Info

I'm really confused on what I've done with my code.
It's just a simple app using Fragments but I get below error :
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.sgrumo.sunshineonyourmind/com.example.sgrumo.sunshineonyourmind.MainActivity}: java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
This is my MainActivity class :
public class MainActivity extends FragmentActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if(savedInstanceState==null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new MainActivityFragment()).commit();
}
}
Activity-main XML :
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:ignore="MergeRootFrame"
tools:context="com.example.sgrumo.sunshineonyourmind.MainActivity">
I just wanted a Fragment inside my activity main, what's wrong with my code?
This is the Fragment class i use :
public class MainActivityFragment extends Fragment {
public MainActivityFragment() {}
String[] forecastArray = {
"Today - Sunny - 31/20",
"Tomorrow - Sunny - 42,30",
"Wednesday - Rainy - 20,15",
"Thursday - FINIMONDO - 35,20"
};
ArrayList<String> list = new ArrayList<>(Arrays.asList(forecastArray));
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(getActivity(),R.layout.list_item_forecast,R.id.list_item_forecast_textview,list);
ListView lw = (ListView)rootView.findViewById(R.id.listview_forecast);
lw.setAdapter(adapter);
return rootView;
}
And its XML :
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.sgrumo.sunshineonyourmind.MainActivityFragment"
tools:showIn="#layout/activity_main">
<ListView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/listview_forecast"
android:layout_gravity="center" />

Please change the code as following in your onCreateView method
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
You missed to add false. Thanks.

Use getSupportFragmentManager().beginTransaction()
.replace(R.id.container, new MainActivityFragment()).commit() instead of getSupportFragmentManager().beginTransaction()
.add(R.id.container, new MainActivityFragment()).commit()

FragmentManager gives me NPE

I'm checking fragments for the first time and I created a LinearLayout with a FrameLayout within and for my layout-sw600dp a LinearLayout with 2 FrameLayouts.
The one has an id of "main" and the other is "details".
The error I get is :
Caused by: java.lang.NullPointerException
at android.app.BackStackRecord.doAddOp(BackStackRecord.java:395)
at android.app.BackStackRecord.add(BackStackRecord.java:385)
at mes.fallstudio.tvfall.MainActivity.onCreate(MainActivity.java:28)
where line 28 is the last line here:
public class MainActivity extends AppCompatActivity {
private android.support.v4.app.Fragment mainFragment;
private android.app.Fragment detailsFragment;
private Boolean isDualPane = false;
private android.support.v4.app.FragmentManager fm;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
android.support.v4.app.FragmentManager fragmentManager = getSupportFragmentManager();
mainFragment = fragmentManager.findFragmentById(R.id.main);
android.support.v4.app.FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.add(R.id.main, mainFragment).commit();
}
}
XML layout files :
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<FrameLayout
android:id="#+id/main"
android:layout_width="match_parent"
android:layout_height="match_parent">
</FrameLayout>
<FrameLayout
android:id="#+id/details"
android:layout_width="match_parent"
android:layout_height="match_parent">
</FrameLayout>
this is for layout-sw600dp and the same without the 2nd FrameLayout ( details) for the xml file for the layout folder.
I'm extending AppCompatActivity if this helps.
Thanks you

AppCompatActivity uses getSupportFragmentManager() instead of getFragmentManager().
Reference: https://developer.android.com/reference/android/support/v7/app/AppCompatActivity.html
EDIT:
In your code you try to get mainFragment from the XML layout. However, you do not define it there. You can either instantiate mainFragment in your code:
mainFragment = new MainFragment();
Or define it in your XML:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<fragment android:name="mes.fallstudio.tvfall.MainFragment"
android:id="#+id/main"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<FrameLayout
android:id="#+id/details"
android:layout_width="match_parent"
android:layout_height="match_parent">
</FrameLayout>
In the latter case you don't need to use the FragmentManager at all in your code unless you need to manipulate the fragments at run time.
In both cases you also need the actual fragment:
public class MainFragment extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.main_fragment, container, false);
}
}

How to create multiple fragments programmatically?

I am trying to show multiple fragments on the one screen by creating them programmatically. I am able to do this no problem by including each fragment into the activities layout file. However when I try and do it programmatically Im confused.This is what I have so far for two fragments on a screen.
Main Class:
public class MainActivity extends FragmentActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
FragmentOne one = new FragmentOne();
FragmentTwo two = new FragmentTwo();
FragmentThree three = new FragmentThree();
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.add(R.id.imOne, one, "fragmentone");
ft.add(R.id.imTwo, two, "fragmenttwo");
ft.add(R.id.imThree, three, "fragmenthree");
ft.commit();
}
}
Fragment One:
public class FragmentOne extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
View view = inflater.inflate(R.layout.frag_one, container, false);
return view;
}
}
Fragment Two:
public class FragmentTwo extends Fragment{
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
View view = inflater.inflate(R.layout.frag_two, container, false);
return view;
}
}
The layout files for my two fragment classes just contain a simple TextView.
And then the activity_main.xml layout file for my main class:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<FrameLayout
android:id="#+id/imOne"
android:name="com.david.twofragexample.FragmentOne"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="2" />
<FrameLayout
android:id="#+id/imTwo"
android:name="com.david.twofragexample.FragmentTwo"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="2" />
<FrameLayout
android:id="#+id/imThree"
android:name="com.david.twofragexample.FragmentThree"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="2" />
</LinearLayout>
When I try and do it programatically I get confused as to what should be in my activity_main.xml file. So from the Android Developer Guide(http://developer.android.com/guide/components/fragments.html) it says to use
FragmentManager fragmentManager = getFragmentManager()
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
FragmentOne fragment = new FragmentOne();
fragmentTransaction.add(R.id.fragment_container, fragment);
fragmentTransaction.commit();
So when I add this code to my onCreate method what changes do I have to make to my activity_main.xml file to do this programmatically?I don't see where R.id.fragment_container comes from. How can I determine where on the screen my new fragment will go?Thanks
EDIT: I am developing this on a tablet and not a phone.This has now been solved and the above code will add three fragments programmatically.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<FrameLayout
android:id="#+id/list"
android:name="com.david.twofragexample.FragmentOne"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="2" />
<FrameLayout
android:id="#+id/viewer"
android:name="com.david.twofragexample.FragmentTwo"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="2" />
</LinearLayout>
In your Activity:
FragmentOne one = new FragmentOne();
FragmentTwo two = new FragmentTwo();
fm = getSupportFragmentManager();
fm.beginTransaction().replace(R.id.list, one, "fragmentone").commit();
fm.beginTransaction().replace(R.id.viewer, two, "fragmenttwo").commit();
I suggest you study this:
http://developer.android.com/reference/android/app/Fragment.html
and fully understand the fragment lifecycle, etc. The way I show is quick and dirty, but not neccesarilly best.

As I don't have higher enough reps to comment yet, I will just leave the information here -- the way Rafael T suggested does work nicely, although I also had my doubt at the first place.
1) Define your xml like this:
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
>
2) Add each fragment into the same slot:
View box = v.findViewById(R.id.container);
FragmentTransaction ft = getFragmentManager().beginTransaction();
for (String catalog : mCatalogs) {
Fragment fragment = HighlightedProductFragment.newInstance(catalog);
ft.add(R.id.container, fragment, catalog);
}
ft.commit();
Thanks for the solution for this tricky requirement.

Try it like this:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
as your activity_main.xml
You asked yourself the right question: where is the id fragment_container, and the answer was: nowhere. >ou also set your layout to horizontal, which makes it very likely, that added Views will be kind of 'out of screen'