Develop Reference

List of fragment in android

I know that to show a list of views I can use recycler view with but what if I wanna reuse also my fragment logic too?
for example, if I have a fragment like this
XML
<androidx.constraintlayout.widget.ConstraintLayout 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=".views.fragments.testview">
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="hi"/>
</androidx.constraintlayout.widget.ConstraintLayout>
Fragment class
public class TestView extends Fragment {
private TextView txt;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.test, container, false);
initComponent(v);
return v;
}
private void hardTask1(){};
private void hardTask2(){};
//Some other hardtask
}
What I could do if I need to display a list of fragments in some activity but I don't want to rewrite all my TestView in the adapter?

On android, when I set the Text of a TextView dynamically it doesn't change

I am new to the android platform so I know I am just missing something by here is what I have
<!-- activity_main -->
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.example_app.MainActivity"
tools:ignore="MergeRootFrame" >
<fragment
android:id="#+id/mainFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
class="com.example.example_app.MainFragment"
/>
</FrameLayout>
Then I created a fragment called MainFragment.java.
public class MainFragment extends Fragment {
public TextView displayTextView;
public MainFragment() { }
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
this.displayTextView = (TextView)rootView.findViewById(R.id.displayTextView);
return rootView;
}
}
I add the fragment in the OnCreate function in the activity and it seems to be adding everything okay but when I click on the button nothing happens, I logged the function to see its being called but setting the textview doesn't do anything. What am I doing wrong?
<RelativeLayout 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.example_app.MainActivity$PlaceholderFragment" >
<Button
android:id="#+id/button10"
android:textColor="#ffffff"
android:textSize="34dp"
android:text="10%"
android:layout_below="#id/amountEditText"
android:background="#drawable/pct_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="doSomething"
/>
<TextView
android:text="Blah Blah Blah"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/displayTextView"
></TextView>
</RelativeLayout>
And here is the click Event in the MainActivity.java
public void doSomething(View v) {
this.mainFragment.displayTextView.setText("Nothing to set for some reason!");
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
//
this.mainFragment = (MainFragment) getSupportFragmentManager().findFragmentById(R.id.mainFragment);
mainFragment = new MainFragment();
getSupportFragmentManager().beginTransaction().add(mainFragment, "mainFragment").commit();
}
}

Declaring onClick-Listeners via XML is possible if you work with Activities. According to the Google API, however, you need to declare OnClickListeners programmatically if you use Fragments.
[...] You can also declare the click event handler programmatically rather than in an XML layout. This might be necessary if you instantiate the Button at runtime or you need to declare the click behavior in a Fragment subclass.
Source:
http://developer.android.com/guide/topics/ui/controls/button.html
So you may want to use this instead:
public class MainFragment extends Fragment {
public TextView displayTextView;
public Button yourButton;
public MainFragment() { }
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
this.displayTextView = (TextView)rootView.findViewById(R.id.displayTextView);
yourButton = (Button)rootView.findViewById(R.id.button10);
yourButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
displayTextView.setText("Nothing to set for some reason!");
}
});
return rootView;
}
}

The problem is the way you try to execute the button click. From your question i understand that Button and TextView is in Fragment view. So do why are Trying to access it in activity ?? It is wrong, then there is no point of using Fragments. Also this will lead to many serious issues later .
Fragments are Reusable components so all the functionalities of a fragment must stay inside the Fragment Class
Change Fragment code :
public class MainFragment extends Fragment {
public TextView displayTextView;
public Button yourButton;
public MainFragment() { }
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
this.displayTextView = (TextView)rootView.findViewById(R.id.displayTextView);
yourButton = (Button)rootView.findViewById(R.id.button10);
//Setting click listener for button in fragment
yourButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
displayTextView.setText("Nothing to set for some reason!");
}
});
return rootView;
}
}
and remove android:onClick="doSomething" from XML

FindViewbyId always returns Null in Fragment

I have an xml file as shown below:
One.xml
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginTop="20dp"
android:background="#drawable/additemsbackground"
android:orientation="horizontal"
android:layout_marginRight="20dp"
android:layout_marginLeft="20dp">
<ImageView
android:id="#+id/btnaddtxt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="right|center_vertical"
android:layout_marginRight="10dp"
android:adjustViewBounds="true"
android:src="#drawable/add" />
</LinearLayout>
This is my MainFragment:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
LayoutInflater layoutInflater = LayoutInflater.from(MainActivity.this);
View myView = layoutInflater.inflate(R.layout.One,
null);
ImageView btnadd=(ImageView)myView.findViewById(R.id.btnaddtxt);
btnadd.setOnClickListener(
new View.OnClickListener() {
#Override
public void onClick(View arg0) {
Toast.makeText(getApplicationContext(),
"Clicked Add Text Button" , Toast.LENGTH_LONG)
.show();
}
});
}
When I'm trying to get the ImageView as shown in my MainFragment it always returns null.
Can anyone say me what's the correct way of doing this ?

Initialize your views in onCreateView(...) and not in onCreate(...) when using Fragments. Something like this
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.delivery_boys, container,
false);
ImageView btnadd=(ImageView)rootView .findViewById(R.id.btnaddtxt);
return rootView;
}

you are suppose to inflate view in onCreateView in your fragment class
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view= inflater.inflate(R.layout.delivery_boys, container,
false);
ImageView img=(ImageView)view.findViewById(R.id.your_img_view);
return view;
}
onCreateView function you get attached to the activity and you get you get view inflation opportunity in onCreate Method Fragment is initialized and not yet attached to activity.

#Override
public View setContentView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
if (mChangeVehiclesView == null) {
mChangeVehiclesView = inflater.inflate(
R.layout.frag_vehicles_registered, null);
} else {
((ViewGroup) mChangeVehiclesView.getParent())
.removeView(mChangeVehiclesView);
}
mvehicleListView = (ListView) mChangeVehiclesView
.findViewById(R.id.frag_vehicle_registeres_list);
return mChangeVehiclesView;
}

SupportMapFragment with a custom layout, possible?

I am trying to have SupportMapFragment with a custom layout, right now the following code works :
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
View view = super.onCreateView(inflater, container, savedInstanceState);
// initMap();
return view;
}
But I want to change the onCreateView() method to inflate a different layout, instead of calling the super.onCreateView() method.
To look like something like this:
View view = inflater.inflate(R.layout.fragment, container,false);
mMap = (GoogleMap)view.findViewById(R.id.mapview);
But GoogleMap is not a view so I cannot add it to the xml, like the following way:
<com.google.android.gms.maps.GoogleMap
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/mapview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>

If you want to create a SupportMapFragment with a custom layout, I prefer to extend the android.support.v4.app.Fragment from the Support Library and inflate your custom XML with the com.google.android.gms.maps.MapView and other views there.
But be careful to forward the livecycle methods to this MapView as quoted here.

I added a LinearLayout above the map.
I used this layout for the buttons:
<?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="wrap_content"
android:id="#+id/llPlaces"
android:orientation="horizontal"
android:background="#color/ACGris">
<Button android:id="#+id/btn1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="BUTTON1"/>
<Button android:id="#+id/btn2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="BUTTON2"/>
<Button android:id="#+id/btn3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="BUTTON3"/>
And then I created a class which extends SupportMapFragment
public class FrgMapas extends SupportMapFragment{
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View viewMain = super.onCreateView(inflater, container, savedInstanceState);
View viewButtons = inflater.inflate(R.layout.layout_buttons, null);
FrameLayout mainChild = (FrameLayout) ((ViewGroup)viewMain).getChildAt(0);
mainChild.addView(viewButtons);
Button btn1 = (Button) viewMain.findViewById(R.id.btn1);
btn1.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(getActivity(), "TuTa :)", Toast.LENGTH_LONG).show();
}
});
return viewMain;
}
Hope this works for you

com.google.android.gms.maps.MapView is a View that you can embed in your layouts.

You can override onCreateView in the class you derive from SupportMapFragment. You can call super.onCreateView and then insert the result into a custom ViewGroup you inflater or instantiate. Here's some sample code
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
FrameLayout layout = (FrameLayout) inflater.inflate(R.layout.my_layout,
container, false);
View v = super.onCreateView(inflater, container, savedInstanceState);
layout.addView(v, 0);
return layout;
}

Android + ListFragment with a custom view hierarchy

I'm attempting to customize the fragment layout by returning my own view hierarchy from onCreateView(LayoutInflater, ViewGroup, Bundle). This inflates my custom view, but seems to stack the views instead of inflating within, I see everything at once. Any help is appreciated.
MyActivity.java:
public class MyActivity extends FragmentActivity{
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getSupportFragmentManager().findFragmentById(android.R.id.content) == null) {
ArrayListFragment list = new ArrayListFragment();
getSupportFragmentManager().beginTransaction().add(android.R.id.content, list).commit();
}
}
public static class ArrayListFragment extends ListFragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
inflater.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
inflater.inflate(R.layout.main, container);
return super.onCreateView(inflater, container, savedInstanceState);
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
String List[] = {"Larry", "Moe", "Curly"};
setListAdapter(new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, List));
}
}
}
main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="8dp"
android:paddingRight="8dp">
<Button
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="THIS IS A BUTTON" />
<ListView
android:id="#android:id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#00FF00"
android:layout_weight="1"
android:drawSelectorOnTop="false" />
<TextView
android:id="#android:id/empty"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#FF0000"
android:text="No data" />
</LinearLayout>

I wasn't returning the new view within the onCreateView method of the ListFragment class. For instance:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.main, null);
return view;
}
All works well now in the land of Android!

I think you'd better
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View root = inflater.inflate(R.layout.main, container, false);
return root;
}

optimized way and shot code
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.list_alphabet, container, false);
}

getSupportFragmentManager().beginTransaction().add(android.R.id.content, list).commit();
List is not accepted, it's looking for a fragment.

use this pattern, works perfectly!
inflater.inflate(R.layout.list_layout, container, false);
public View inflate (XmlPullParser parser, ViewGroup root, boolean attachToRoot)
attachToRoot Whether the inflated hierarchy should be attached to the root parameter? If false, root is only used to create the correct subclass of LayoutParams for the root view in the XML.