Develop Reference

How to use MVVM with any fragment?

I have a TabLayout on a activity and when user clicks on any tab then a fragment is loaded. One of those fragments contains a NavigationView running inside a DrawerLayout. Now the problem is I have to implement MVVM for the whole app and so for the fragments too, I have done this for Activities but I am having trouble while implementing this for Fragments and how to deal with ItemSelected with MVVM and what to bind and how? I am unable to find a proper working sample of the same. Here's the code:
MoreFragment.java:
package com.abc.Fragments;
import android.arch.lifecycle.ViewModel;
import android.arch.lifecycle.ViewModelProviders;
import android.content.Context;
import android.net.Uri;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.design.widget.NavigationView;
import android.support.v4.app.Fragment;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
import com.abc.MainActivity;
import com.abc.MoreFragmentViewModel;
import com.abc.R;
public class MoreFragment extends Fragment {
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
private ViewModel viewModel;
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
viewModel = ViewModelProviders.of(this).get(MoreFragmentViewModel.class);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View fragView = inflater.inflate(R.layout.fragment_more, container, false);
return fragView;
}
#Override
public void onViewCreated(#NonNull View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
mDrawerLayout = getView().findViewById(R.id.drawer_layout);
mDrawerLayout.openDrawer(Gravity.END);
}
}
fragment_more.xml:
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/white">
<android.support.design.widget.NavigationView
android:id="#+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="end"
android:background="#color/grey"
app:navigationItemSelectedListener="#{()-> viewModel.onMyItemSelected()}"
app:headerLayout="#layout/nav_header_main"
app:menu="#menu/activity_main_drawer" />
</android.support.v4.widget.DrawerLayout>
MoreFragmentViewModel.java:
package com.abc;
import android.arch.lifecycle.ViewModel;
import android.databinding.BaseObservable;
public class MoreFragmentViewModel extends ViewModel {
public void onMyItemSelected(){
System.out.print("Item Clicked");
}
}
Please do any possible help.

Use:
DataBindingUtil.inflate(inflater, layoutId(), container, false)
To inflate your layout.
And don't forget to add:
<data>
<variable
name="model"
type="MoreFragmentViewModel"/>
</data>
To your fragment layout.

Render error Unknown Fragment Android Studio

Hello I am wondering how to clear a render error I am having with a fragment which is saying unknown fragment. I can seem to find what I did wrong to fix it. I have a recycleview in the fragment that is just a test to make sure that is working as well right now.
Here is the Xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
android:orientation="vertical"
tools:context="jlfletcher.cpsc4367.ualr.edu.hw2.MainActivity">
<fragment
android:id="#+id/fragmentone"
android:name="layout.FragmentOne"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
Here is the Java of the fragment
package layout;
import android.app.Activity;
import android.content.Context;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.List;
import jlfletcher.cpsc4367.ualr.edu.hw2.CPSClist;
import jlfletcher.cpsc4367.ualr.edu.hw2.R;
public class FragmentOne extends Fragment
{
public void OnCreate(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
View View = inflater.inflate(R.layout.fragment_fragment_one, container, false);
RecyclerView recyclerView =
(RecyclerView)View.findViewById(R.id.Class_list);
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
CPSClist textAdapter= new CPSClist();
recyclerView.setAdapter(textAdapter);
List<String> stringList = new ArrayList<>();
stringList.add("This");
stringList.add("is");
stringList.add("a");
stringList.add("of");
stringList.add("the");
stringList.add("recycle");
stringList.add("view");
stringList.add("system");
stringList.add("this");
stringList.add("is");
stringList.add("only");
stringList.add("a");
stringList.add("test.");
List<String> list = new ArrayList<>();
list.addAll(stringList);
list.addAll(stringList);
list.addAll(stringList);
list.addAll(stringList);
list.list(stringList);
list.addAll(stringList);
textAdapter.setItems(list);
}
}
Thanks again for the help on this.

Facing Issues when working with fragment

I have to create an application in which I have to work with Fragment.
In the MainActivity, there is a webView. From the SecondActivity I
have starting using Fragment.
Here is the code of SecondActivity:
package com.dev.testapp;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.view.View;
public class Second extends Activity {
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.second);
}
public void choosefragment(View view) {
Fragment fg;
if(view == findViewById(R.id.secondbtn2)) {
fg = new SecondFragment();
}
else
{
fg = new FirstFragment();
}
FragmentManager fm = getFragmentManager();
FragmentTransaction fragmentTransaction = fm.beginTransaction();
fragmentTransaction.replace(R.id.frag1, fg);
fragmentTransaction.commit();
}
}
Hhere is its second.xml file:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
android:background="#ffffff" >
<Button
android:id="#+id/secondbtn1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="first fragment"
android:onClick="chooseFragment" />
<Button
android:id="#+id/secondbtn2"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="second fragment"
android:onClick="chooseFragment"/>
<fragment
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:name="com.dev.testapp.fragment1"
android:id="#+id/frag1"
/>
</LinearLayout>
After that I created two more classes for Fragments as it is required
code of FirstFragment:
package com.dev.testapp;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class FirstFragment extends Fragment{
public View onCreate(LayoutInflater inflater,
ViewGroup container , Bundle savedInstanceState) {
//Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment1,container, false);
}
}
And here is the SecondFragment:
package com.dev.testapp;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class SecondFragment extends Fragment{
public View onCreate(LayoutInflater inflater,
ViewGroup container , Bundle savedInstanceState) {
//Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment2,container, false);
}
}
When I am done with all this, my SecondActivity is showing an error that I don't know how to handle:

As noted in previous answers, your problem is incorrect Fragment library for FirstFragment.
Change line 5 of FirstFragment.java:
import android.support.v4.app.Fragment;
to:
import android.app.Fragment;

Your second fragment is of the type android.app.Fragment while your first fragment is android.support.v4.app.Fragment.

your activity use this import android.app.Fragment;
your fragment is import android.support.v4.app.Fragment;
So you either have both extending the Fragment in the app package or in the support library

android layout is not displaying

I know its probably something simple I am missing here, but for some reason I can't seem to get my layout to display when I run my app using the emulator. Any feedback would be great. Thanks
my fragment
package com.pctoolman.planme.app;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
public class PlanMeMainFragment extends Fragment {
private Button mNewButton, mExistingButton;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.planme_main_fragment, container, false);
mNewButton = (Button)v.findViewById(R.id.new_event_button);
mNewButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent myIntent = new Intent(getActivity(), NewEventSetupActivity.class);
getActivity().startActivity(myIntent);
}
});
return v;
}
}
my layout file:
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:background="#ff3a0b">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:text="#string/plan_me"
android:textSize="36dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="2"
android:gravity="center|top"
android:textAlignment="center"
android:textColor="#2c58ff"
android:id="#+id/textView">
</TextView>
</LinearLayout>
<Button
android:id="#+id/new_event_button"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:layout_gravity="bottom"
android:padding="5dp"
android:text="#string/new_event"
android:layout_centerHorizontal="true"
android:layout_marginTop="160dp" />
<Button
android:id="#+id/existing_event"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:padding="5dp"
android:text="#string/existing_event"
android:layout_centerHorizontal="true"
android:layout_marginTop="260dp"/>
</RelativeLayout>
here is the activity file
package com.pctoolman.planme.app;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
public class PlanMeMainActivity extends FragmentActivity {
#Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.planme_main_activity);
}
}

You should make a transatcion via FragmentManager to show your fragment in the activity. Suppose you have container (FrameLayout, for example) with id = fragment_container in your planme_main_activity.xml. If so, you should add the following after setContentView(R.layout.planme_main_activity);:
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.fragment_container, new PlanMeMainFragment())
.commit();
But if you declared fragment directly in XML, please post your planme_main_activity.xml

Maybe it's because you haven't positioned the buttons properly. It's easy to move things around in a relative layout. You don't need to use gravity. You can use:
android:layout_alignParentBottom="true"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_above="#+id/btn"
android:layout_below="#+id/btn"
I'm assuming you cut out the closing tag for the RL.

Error: The method add(int, Fragment, String) in the type FragmentTransaction is not applicable for the arguments (int, FragementTest, String)

Im trying to Use Fragements. But in MainActivity.java file the transaction.add(R.id.my_layout, testfrag, "");not Initiated correctly.please find below the code i used.
package com.example.testtabs;
import android.os.Bundle;
import android.app.Activity;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.app.TabActivity;
import android.view.Menu;
import android.widget.TabHost;
import android.support.v4.app.Fragment;
import com.example.testtabs.R;
public class MainActivity extends TabActivity {
TabHost tab;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
FragementTest testfrag=new FragementTest();
FragmentManager manager=getFragmentManager();
FragmentTransaction transaction=manager.beginTransaction();
transaction.add(R.id.my_layout, testfrag, "");//Error is here
}
}
activity_main.xml :
<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=".MainActivity"
android:id="#+id/my_layout"
>
Error: The method add(int, Fragment, String) in the type FragmentTransaction is not applicable for the arguments (int, FragementTest, String)
Fragement.test
package com.example.testtabs;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
/**
* A simple {#link android.support.v4.app.Fragment} subclass.
*
*/
public class FragementTest extends Fragment {
public FragementTest() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_fragement, container, false);
}
}

change:
import android.app.FragmentManager;
import android.app.FragmentTransaction;
to:
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
or---
change:
import android.support.v4.app.Fragment;
to
import android.app.Fragment;

All the Fragment should be android.app.Fragment. If you want to use android.support.v4.app.Fragment, you should use getSupportFragmentManager() to get the Manager.

Its working for me:
Instead of using getFragmentManager use getSupportFragmentManager();