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no instance(s) of type variable(s) exist so that Integer conforms to View

I'm trying to Develop an android apps with recycler view. So I created an item view, a model class and adapter. In Adatper.java class inside viewHolder method, showing errors while I initializing variables, and I can't figure out what is wrong with the following piece of code.
here is code for item_view_model.xml
<?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"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="90dp">
<androidx.cardview.widget.CardView
android:id="#+id/imageView"
android:layout_width="60dp"
android:layout_height="60dp"
android:layout_margin="20dp"
app:cardCornerRadius="60dp"
app:cardElevation="10dp">
<ImageView
android:id="#+id/imagesme"
android:layout_width="60dp"
android:layout_height="60dp"
android:scaleType="centerCrop"
android:src="#drawable/download" />
</androidx.cardview.widget.CardView>
<TextView
android:id="#+id/textname"
android:layout_width="150dp"
android:layout_height="wrap_content"
android:layout_toRightOf="#+id/imageView"
android:layout_marginTop="20dp"
android:text="#string/syed_bipul_rahman"
android:textColor="#000"
android:textStyle="bold" />
<TextView
android:id="#+id/podobi"
android:layout_width="150dp"
android:layout_height="wrap_content"
android:text="#string/professor"
android:layout_below="#id/textname"
android:layout_toRightOf="#+id/imageView"
android:textColor="#000"
android:textStyle="bold" />
</RelativeLayout>
</RelativeLayout>
here is code of ModelClass.java
package com.school.recyclerview;
public class ModelClass {
public ModelClass(int imagesme, String textname, String podobi) {
this.imagesme = imagesme;
this.textname = textname;
this.podobi = podobi;
}
private int imagesme;
private String textname;
private String podobi;
public int getImagesme() {
return imagesme;
}
public void setImagesme(int imagesme) {
this.imagesme = imagesme;
}
public String getTextname() {
return textname;
}
public void setTextname(String textname) {
this.textname = textname;
}
public String getPodobi() {
return podobi;
}
public void setPodobi(String podobi) {
this.podobi = podobi;
}
}
and these codes for ** Adapter.java**
package com.school.recyclerview;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import java.util.List;
public class Adapter extends RecyclerView.Adapter<Adapter.ViewHolder> {
private List<ModelClass> userList;
public Adapter(List<ModelClass> userList) {
this.userList = userList;
}
#NonNull
#Override
public Adapter.ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_view_model, parent, false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull Adapter.ViewHolder holder, int position) {
int userImg = userList.get(position).getImagesme();
String userNames = userList.get(position).getTextname();
String userPost = userList.get(position).getPodobi();
holder.setData(userImg, userNames, userPost);
}
#Override
public int getItemCount() {
return userList.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
private int imageview;
private String textmyname, podobi;
public ViewHolder(#NonNull View itemView) {
super(itemView);
imageview = itemView.findViewById(R.id.imagesme);
textmyname = itemView.findViewById(R.id.textname);
podobi = itemView.findViewById(R.id.podobi);
}
public void setData(int userImg, String userNames, String userPost) {
imageview.setImageResource(userImg);
textmyname.setText(userNames);
podobi.setText(userPost);
}
}
}
How to solve this problem??

Try changing the types of imageview, textmyname and podobi in your ViewHolder Class:
private ImageView imageview;
private TextView textmyname, podobi;
instead of
private int imageview;
private String textmyname, podobi;

how to make an Android RecyclerView Load More, Endless Scrolling with progress bar(half visible)?

I have made a endless scrolling with using progress bar with recycle view and also use fire-store for data retrieving. My problem is, the progress bar is not at appropriate position/visible(half visible) on the screen.
here below I have pasted my code:
activity_main.xml
this is activity main XML file.
<?xml version="1.0" encoding="utf-8"?>
<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=".MainActivity">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:scrollbars="vertical"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ProgressBar
android:id="#+id/isLoading"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:visibility="gone"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ProgressBar
android:id="#+id/isLoadingMore"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="16dp"
android:visibility="gone"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/recyclerView" />
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:id="#+id/floatingActionButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="16dp"
android:layout_marginBottom="16dp"
android:clickable="true"
android:contentDescription="#string/todo"
android:focusable="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:srcCompat="#android:drawable/ic_input_add" />
</androidx.constraintlayout.widget.ConstraintLayout>
MainActivity.java
this is main activity JAVA file.
package com.IUDV;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.os.Bundle;
import android.view.View;
import android.widget.AbsListView;
import android.widget.ProgressBar;
import android.widget.Toast;
import com.IUDV.Adapters.NotesShowsAdapter;
import com.IUDV.models.NoteShow;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.firebase.firestore.CollectionReference;
import com.google.firebase.firestore.DocumentSnapshot;
import com.google.firebase.firestore.FirebaseFirestore;
import com.google.firebase.firestore.Query;
import com.google.firebase.firestore.QuerySnapshot;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Random;
import java.util.Set;
import java.util.UUID;
public class MainActivity extends AppCompatActivity {
private final List<NoteShow> noteShows = new ArrayList<>();
private NotesShowsAdapter notesShowsAdapter;
private RecyclerView recyclerView;
private ProgressBar loadingPB, loadingMorePB;
private int limit = 15;
private DocumentSnapshot lastVisible;
private boolean isScrolling = false;
private boolean isLastItemReached = false;
private FirebaseFirestore rootRef;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recyclerView = findViewById(R.id.recyclerView);
loadingPB = findViewById(R.id.isLoading);
loadingMorePB = findViewById(R.id.isLoadingMore);
notesShowsAdapter = new NotesShowsAdapter(noteShows);
recyclerView.setAdapter(notesShowsAdapter);
recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
#Override
public void onScrolled(#NonNull RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
}
});
rootRef = FirebaseFirestore.getInstance();
CollectionReference productsRef = rootRef.collection("notes");
Query query = productsRef.orderBy("title", Query.Direction.ASCENDING).limit(limit);
loadingPB.setVisibility(View.VISIBLE);
query.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
#Override
public void onComplete(#NonNull Task<QuerySnapshot> task) {
if (task.isSuccessful()) {
for (DocumentSnapshot document : task.getResult()) {
noteShows.add(new NoteShow(document.get("id").toString(),document.get("title").toString(),document.get("description").toString()));
}
notesShowsAdapter.notifyDataSetChanged();
loadingPB.setVisibility(View.GONE);
lastVisible = task.getResult().getDocuments().get(task.getResult().size() - 1);
RecyclerView.OnScrollListener onScrollListener = new RecyclerView.OnScrollListener() {
#Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
if (newState == AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL) {
isScrolling = true;
}
}
#Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
LinearLayoutManager linearLayoutManager = ((LinearLayoutManager) recyclerView.getLayoutManager());
int firstVisibleItemPosition = linearLayoutManager.findFirstVisibleItemPosition();
int visibleItemCount = linearLayoutManager.getChildCount();
int totalItemCount = linearLayoutManager.getItemCount();
if (isScrolling && (firstVisibleItemPosition + visibleItemCount == totalItemCount) && !isLastItemReached) {
loadingMorePB.setVisibility(View.VISIBLE);
isScrolling = false;
Query nextQuery = productsRef.orderBy("title", Query.Direction.ASCENDING).startAfter(lastVisible).limit(limit);
nextQuery.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
#Override
public void onComplete(#NonNull Task<QuerySnapshot> t) {
if (t.isSuccessful()) {
for (DocumentSnapshot d : t.getResult()) {
noteShows.add(new NoteShow(d.get("id").toString(),d.get("title").toString(),d.get("description").toString()));
}
notesShowsAdapter.notifyDataSetChanged();
loadingMorePB.setVisibility(View.GONE);
lastVisible = t.getResult().getDocuments().get(t.getResult().size() - 1);
if (t.getResult().size() < limit) {
isLastItemReached = true;
}
}
}
});
}
}
};
recyclerView.addOnScrollListener(onScrollListener);
}else {
loadingPB.setVisibility(View.GONE);
}
}
});
}
}
NoteShow.java
this is model file.
package com.IUDV.models;
public class NoteShow {
private String id;
private String title;
private String description;
public NoteShow(String id, String title, String description) {
this.id = id;
this.title = title;
this.description = description;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
}
NotesShowsAdapter.java
this is Adapter file
package com.IUDV.Adapters;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import com.IUDV.R;
import com.IUDV.models.NoteShow;
import java.util.List;
public class NotesShowsAdapter extends RecyclerView.Adapter<NotesShowsAdapter.ViewHolder> {
private List<NoteShow> noteShowList;
public NotesShowsAdapter(List<NoteShow> noteShowList) {
this.noteShowList = noteShowList;
}
#NonNull
#Override
public NotesShowsAdapter.ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.view_layout, parent, false);
return new NotesShowsAdapter.ViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull NotesShowsAdapter.ViewHolder holder, int position) {
holder.txtTitle.setText(noteShowList.get(position).getTitle());
holder.txtDesc.setText(noteShowList.get(position).getDescription());
}
#Override
public int getItemCount() {
return noteShowList.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
private TextView txtTitle;
private TextView txtDesc;
public ViewHolder(#NonNull View itemView) {
super(itemView);
txtTitle = itemView.findViewById(R.id.textTitle);
txtDesc = itemView.findViewById(R.id.textDesc);
}
}
}
view_layout.xml
this is item layout file.
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:background="#drawable/background_note"
android:layout_height="wrap_content">
<TextView
android:id="#+id/textTitle"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Title"
android:textSize="16sp"
android:textColor="#color/black"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/textDesc"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:text="Description"
android:textSize="14sp"
android:textStyle="bold"
android:textColor="#color/black"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/textTitle" />
</androidx.constraintlayout.widget.ConstraintLayout>

E/Volley: [6074] BasicNetwork.performRequest: Unexpected response code 403 for

activity_main.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=".MainActivity">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/rView"
android:layout_width="409dp"
android:layout_height="729dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
2.activity_frame.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView 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="500dp">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="#+id/imageView"
android:layout_width="411dp"
android:layout_height="360dp"
android:scaleType="centerCrop"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
tools:srcCompat="#tools:sample/avatars"
android:contentDescription="#string/todo" />
<TextView
android:id="#+id/textView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/textview1"
android:textSize="18sp"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/imageView"
app:layout_constraintVertical_bias="0.173" />
<TextView
android:id="#+id/textView2"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="#string/textview2"
android:maxLines="1"
android:ellipsize="end"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="#+id/textView1"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/textView1" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.cardview.widget.CardView>
HDNews.java
package com.example.android.hdnews;
public class HDNews {
private String title;
private String author;
private String image;
public HDNews(String title, String author, String image) {
this.title = title;
this.author = author;
this.image = image;
}
public String getTitle() {
return title;
}
public String getAuthor() {
return author;
}
public String getImage() {
return image;
}
}
MainActivity.java
package com.example.android.hdnews;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.os.Bundle;
import android.widget.LinearLayout;
import com.android.volley.NetworkResponse;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.Volley;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
private RecyclerView recyclerView;
private ArrayList al;
private HDNewsAdapter hdNewsAdapter;
private RequestQueue requestQueue;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recyclerView=findViewById(R.id.rView);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
al=new ArrayList<HDNews>();
requestQueue= Volley.newRequestQueue(this);
extractingDataFromInternet();
}
//http://newsapi.org/v2/top-headlines?country=in&apiKey=94bf8bcc374b494485309e325e3656f9
public void extractingDataFromInternet(){
String url="http://newsapi.org/v2/top-headlines?country=in&category=business&apiKey=94bf8bcc374b494485309e325e3656f9";
JsonObjectRequest JsonObjReq=new JsonObjectRequest(Request.Method.GET, url, null, new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
try {
JSONArray jsonArray = response.getJSONArray("articles");
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject ca = jsonArray.getJSONObject(i);
String authorNames = ca.optString("author");
String titleNames = ca.optString("title");
String imageUrls = ca.getString("urlToImage");
al.add(new HDNews(titleNames, authorNames, imageUrls));
}
hdNewsAdapter = new HDNewsAdapter(MainActivity.this, al);
recyclerView.setAdapter(hdNewsAdapter);
} catch ( JSONException e ) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
}
});
requestQueue.add(JsonObjReq);
}
}
HDNewsAdapter
package com.example.android.hdnews;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import com.bumptech.glide.Glide;
import java.util.ArrayList;
public class HDNewsAdapter extends RecyclerView.Adapter<HDNewsAdapter.ViewHolder>{
private Context context;
private ArrayList<HDNews> al;
public HDNewsAdapter(Context context, ArrayList<HDNews> al) {
this.context = context;
this.al = al;
}
#NonNull
#Override
public HDNewsAdapter.ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View views= LayoutInflater.from(parent.getContext()).inflate(R.layout.activity_frame,parent,false);
return new ViewHolder(views);
}
#Override
public void onBindViewHolder(#NonNull ViewHolder holder, int position) {
HDNews currentposition=al.get(position);
String imgurl=currentposition.getImage();
String athName=currentposition.getAuthor();
String ttleName=currentposition.getTitle();
holder.titleName01.setText(ttleName);
holder.authorName01.setText(athName);
Glide.with(context).load(imgurl).into(holder.imageurl01);
}
#Override
public int getItemCount() {
return al.size();
}
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
public TextView authorName01;
public TextView titleName01;
public ImageView imageurl01;
public ViewHolder(#NonNull View itemView) {
super(itemView);
authorName01=itemView.findViewById(R.id.textView1);
titleName01=itemView.findViewById(R.id.textView2);
imageurl01=itemView.findViewById(R.id.imageView);
}
#Override
public void onClick(View view) {
}
}
}

Showing xml for correct view

When a user logs in to my app, they can either click the view students button or daily grading button. The view students will display a student's image and their name. The daily grading will display the student's image, name, and two checkboxes that says pass or fail. Now the issue I have is that the checkboxes for pass and fail are showing up in my activity_view_students.xml view when it should not be. It should only show when a user clicks daily grading. I will put images below to make it clearer
What it looks like in the activity_view_students.xml
What it should look like in activity_view_students.xml
I will paste all relevant code below.
ViewStudents.java
package com.example.studenttracker;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.GridLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.Query;
import com.google.firebase.database.ValueEventListener;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
public class ViewStudents extends AppCompatActivity {
RecyclerView recyclerView;
Button addStudent;
private DatabaseReference myRef;
public ArrayList<Students> students;
private RecyclerAdapter recyclerAdapter;
private Button orderStudents;
private EditText mEditTextAge;
private EditText mEditTextAssignment;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view_students);
recyclerView = findViewById(R.id.recyclerView);
addStudent = findViewById(R.id.addStudentButton);
mEditTextAge = findViewById(R.id.EditTextAge);
mEditTextAssignment = findViewById(R.id.EditTextAssignment);
orderStudents = findViewById(R.id.orderStudents);
addStudent.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(ViewStudents.this, AddStudent.class));
}
});
recyclerView.setLayoutManager(new GridLayoutManager(this, 2));
recyclerView.setHasFixedSize(true);
myRef = FirebaseDatabase.getInstance().getReference();
students = new ArrayList<>();
ClearAll();
GetDataFromFirebase();
}
private void GetDataFromFirebase() {
Query query = myRef.child("student");
query.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
ClearAll();
for(DataSnapshot snapshot: dataSnapshot.getChildren()) {
Students student = new Students();
if (snapshot.child("url").getValue() == null) {
student.setImageUrl(snapshot.child("imageUrl").getValue().toString());
}
else {
student.setImageUrl(snapshot.child("url").getValue().toString());
}
// student.setAge(mEditTextAge.getText().toString());
// student.setAssignment(mEditTextAssignment.getText().toString().trim());
student.setName(snapshot.child("name").getValue().toString());
students.add(student);
}
recyclerAdapter = new RecyclerAdapter(getApplicationContext(), students);
recyclerView.setAdapter(recyclerAdapter);
recyclerAdapter.notifyDataSetChanged();
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}
private void ClearAll() {
if (students != null) {
students.clear();
if(recyclerAdapter != null) {
recyclerAdapter.notifyDataSetChanged();
}
}
students = new ArrayList<>();
}
public void orderStudents(View view) {
Collections.sort( students, new Comparator<Students>() {
#Override
public int compare( Students o1, Students o2 ) {
return o1.name.compareTo( o2.name );
}
});
recyclerAdapter.notifyDataSetChanged();
}
}
RecyclerAdapter.java
package com.example.studenttracker;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.ImageView;
import android.view.ViewGroup;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import com.bumptech.glide.Glide;
import java.util.ArrayList;
public class RecyclerAdapter extends RecyclerView.Adapter<RecyclerAdapter.ViewHolder> {
private OnItemClickListener mListener;
public interface OnItemClickListener {
void onItemClick(int position);
}
public void setOnItemClickListener(OnItemClickListener listener) {
mListener = listener;
}
private static final String Tag = "RecyclerView";
private Context mContext;
private ArrayList<Students> studentsArrayList;
public RecyclerAdapter(Context mContext, ArrayList<Students> studentsArrayList) {
this.mContext = mContext;
this.studentsArrayList = studentsArrayList;
}
#NonNull
#Override
public RecyclerAdapter.ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.activity_student_item,parent,false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull ViewHolder holder, int position) {
//TextView
holder.textView.setText(studentsArrayList.get(position).getName());
Glide.with(mContext).load(studentsArrayList.get(position).getImageUrl()).into(holder.imageView);
// if (studentsArrayList.get(position).get) { //check if you need the buttons or not
// holder..setVisibility(View.VISIBLE);
// holder.checkBox2.setVisibility(View.VISIBLE);
// } else {
// holder.checkBox.setVisibility(View.GONE);
// holder.checkBox2.setVisibility(View.GONE);
// }
}
#Override
public int getItemCount() {
return studentsArrayList.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
ImageView imageView;
TextView textView;
public ViewHolder(#NonNull View itemView) {
super(itemView);
imageView = itemView.findViewById(R.id.imageView);
textView = itemView.findViewById(R.id.textView);
itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (mListener != null) {
int position = getAdapterPosition();
}
}
});
}
}
}
activity_view_students.xml
<?xml version="1.0" encoding="utf-8"?>
<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=".ViewStudents">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyclerView"
android:layout_width="409dp"
android:layout_height="729dp"
android:layout_marginEnd="1dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent" >
</androidx.recyclerview.widget.RecyclerView>
<Button
android:id="#+id/addStudentButton"
android:layout_width="wrap_content"
android:layout_height="50dp"
android:text="Add Students"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/orderStudents"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="orderStudents"
android:text="Order Students"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
daily_grading.xml
<?xml version="1.0" encoding="utf-8"?>
<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=".DailyGrading">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyclerView"
android:layout_width="409dp"
android:layout_height="729dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
activity_student_item.xml
<?xml version="1.0" encoding="utf-8"?>
<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="wrap_content"
tools:context=".DailyGrading">
<androidx.cardview.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="50dp"
android:foreground="?android:attr/selectableItemBackground"
app:cardElevation="2dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
</androidx.cardview.widget.CardView>
<RelativeLayout
android:id="#+id/relativeLayout2"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="5dp"
tools:layout_editor_absoluteX="0dp"
tools:layout_editor_absoluteY="52dp">
<ImageView
android:id="#+id/imageView"
android:layout_width="match_parent"
android:layout_height="200dp"
android:layout_marginTop="50dp"
android:paddingTop="20dp"
android:scaleType="centerCrop" />
<TextView
android:id="#+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/imageView"
android:layout_margin="10dp"
android:textSize="16sp" />
<CheckBox
android:id="#+id/passc"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#id/textView"
android:text="PASS" />
<CheckBox
android:id="#+id/failc"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#id/textView"
android:layout_toRightOf="#+id/passc"
android:text="FAIL" />
</RelativeLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
GradingRecyclerAdapter
package com.example.studenttracker;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.view.ViewGroup;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import com.bumptech.glide.Glide;
import java.util.ArrayList;
public class GradingRecyclerAdapter extends RecyclerView.Adapter<GradingRecyclerAdapter.ViewHolder> {
private OnItemClickListener mListener;
public interface OnItemClickListener {
void onItemClick(int position);
}
public void setOnItemClickListener(OnItemClickListener listener) {
mListener = listener;
}
private static final String Tag = "RecyclerView";
private Context mContext;
private ArrayList<Students> studentsArrayList;
public GradingRecyclerAdapter(Context mContext, ArrayList<Students> studentsArrayList) {
this.mContext = mContext;
this.studentsArrayList = studentsArrayList;
}
#NonNull
#Override
public GradingRecyclerAdapter.ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.activity_grading_student_item,parent,false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull ViewHolder holder, int position) {
//TextView
holder.textView.setText(studentsArrayList.get(position).getName());
Glide.with(mContext).load(studentsArrayList.get(position).getImageUrl()).into(holder.imageView);
}
#Override
public int getItemCount() {
return studentsArrayList.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
ImageView imageView;
TextView textView;
Button passButton;
Button failButton;
public ViewHolder(#NonNull View itemView) {
super(itemView);
imageView = itemView.findViewById(R.id.imageView);
textView = itemView.findViewById(R.id.textView);
passButton = itemView.findViewById(R.id.PASS);
failButton = itemView.findViewById(R.id.FAIL);
// passButton.setVisibility(View.GONE);
// failButton.setVisibility(View.GONE);
itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (mListener != null) {
int position = getAdapterPosition();
}
}
});
}
}
}
activity_grading_student_item
<?xml version="1.0" encoding="utf-8"?>
<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="wrap_content"
tools:context=".DailyGrading">
<androidx.cardview.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="50dp"
android:foreground="?android:attr/selectableItemBackground"
app:cardElevation="2dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
</androidx.cardview.widget.CardView>
<RelativeLayout
android:id="#+id/relativeLayout2"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="5dp"
tools:layout_editor_absoluteX="0dp"
tools:layout_editor_absoluteY="52dp">
<ImageView
android:id="#+id/imageView"
android:layout_width="match_parent"
android:layout_height="200dp"
android:layout_marginTop="50dp"
android:paddingTop="20dp"
android:scaleType="centerCrop" />
<TextView
android:id="#+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/imageView"
android:layout_margin="10dp"
android:textSize="16sp" />
<CheckBox
android:id="#+id/PASS"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#id/textView"
android:text="PASS" />
<CheckBox
android:id="#+id/FAIL"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#id/textView"
android:layout_toRightOf="#+id/PASS"
android:text="FAIL" />
</RelativeLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

You can simply use different adapters
create another activity_student_item.xml let's say activity_view_student_item.xml and remove the checkboxes from that one
create another adapter for that recyclerView but change
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.activity_student_item,parent,false);
in the new adapter to
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.activity_view_student_item,parent,false);
and in the ViewStudents activity set the recycler's Adapter to that new adapter

An unordered RecycleView list after scrolling

If I scroll this list RecycleView with the mouse wheel my items in the list look like unordered.
I do not understand , why?
An incorrect clicked item in the new activity from RecycleView
I have tried to create the separate class CrimeAdapter extends RecyclerView.Adapter<CrimeAdapter.CrimeHolder> and
class CrimeHolder extends RecyclerView.ViewHolder implements View.OnClickListener in the separate file, but I couldn't do it right.
Unfornuntely, I do not have enough experience for this.
I do not know how to write the correct code in the method public void onClick(View v)
Crime.java
package com.bignerdranch.android.criminalintent;
import java.util.Date;
import java.util.UUID;
public class Crime{
private UUID mId;
private String mTitle;
private Date mDate;
private boolean mSolved;
private boolean mRequiresPolice;
public Crime() {
// Generate unique identifier
this(UUID.randomUUID());
}
public Crime(UUID id) {
mId = id;
mDate = new Date();
}
public UUID getId() {
return mId;
}
public String getTitle() {
return mTitle;
}
public void setTitle(String title) {
mTitle = title;
}
public Date getDate() {
return mDate;
}
public void setDate(Date date) {
mDate = date;
}
public boolean isSolved() {
return mSolved;
}
public void setSolved(boolean solved) {
mSolved = solved;
}
public boolean isRequiresPolice() {
return mRequiresPolice;
}
public void setRequiresPolice(boolean requiresPolice) {
mRequiresPolice = requiresPolice;
}
}
CrimeLab.java
package com.bignerdranch.android.criminalintent;
import android.content.Context;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.UUID;
public class CrimeLab {
private static CrimeLab sCrimeLab;
private List<Crime> mCrimes;
public static CrimeLab get(Context context) {
if (sCrimeLab == null) {
sCrimeLab = new CrimeLab(context);
}
return sCrimeLab;
}
private CrimeLab(Context context){
mCrimes = new ArrayList<>();
for (int i = 0; i < 100; i++) {
Crime crime = new Crime();
crime.setTitle("Crime #" + i);
crime.setSolved(i % 2 == 0);
if (i % 4 == 0 ) {crime.setRequiresPolice(true);}
else {crime.setRequiresPolice(false);}
mCrimes.add(crime);
}
}
public List<Crime> getCrimes() {
return mCrimes;
}
public Crime getCrime(UUID id){
for (Crime crime : mCrimes){
int rez = id.compareTo(crime.getId());
if (crime.getId().equals(id)){
return crime;
}
}
return null;
}
}
CrimeListFragment.java
package com.bignerdranch.android.criminalintent;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.text.format.DateFormat;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.LayoutRes;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import java.util.Date;
import java.util.List;
public class CrimeListFragment extends Fragment {
private static final int REQUEST_CRIME = 1;
private static final int NOT_REQUIRES_POLICE = 0;
private static final int REQUIRES_POLICE = 1;
private RecyclerView mCrimeRecyclerView;
private CrimeAdapter mAdapter;
private TextView mTitleTextView;
private TextView mDateTextView;
private ImageView mSolvedImageView;
private Button mButtonCallPolice;
private Crime mCrime;
private CharSequence mDateFormat;
private int layout;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_crime_list, container,
false);
mCrimeRecyclerView = (RecyclerView) view
.findViewById(R.id.crime_recycler_view);
mCrimeRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
updateUI();
return view;
}
private class CrimeHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
public CrimeHolder(int layout, LayoutInflater inflater, ViewGroup parent ) {
super(inflater.inflate(layout, parent, false));
mTitleTextView = (TextView) itemView.findViewById(R.id.crime_title);
mDateTextView = (TextView) itemView.findViewById(R.id.crime_date);
mSolvedImageView = (ImageView) itemView.findViewById(R.id.crime_solved);
if (itemView.findViewById(R.id.call_police)!=null) {
mButtonCallPolice = (Button) itemView.findViewById(R.id.call_police);
}
itemView.setOnClickListener(this);
}
public void bind(Crime crime) {
mCrime = crime;
mTitleTextView.setText(mCrime.getTitle());
mDateFormat = DateFormat.format("EEE, MMM dd, yyyy", mCrime.getDate());
mDateTextView.setText(mDateFormat);
mSolvedImageView.setVisibility(mCrime.isSolved() ? View.VISIBLE :
View.GONE);
if(mCrime.isRequiresPolice()){
mButtonCallPolice.setEnabled(true);
}
}
#Override
public void onClick(View view) {
Intent intent = CrimePagerActivity.newIntent(getActivity(),
CrimeLab.get(requireActivity()).getCrimes().get((getAdapterPosition())).getId());
startActivityForResult(intent, REQUEST_CRIME);
}
}
private class CrimeAdapter extends RecyclerView.Adapter<CrimeHolder> {
private List<Crime> mCrimes;
public CrimeAdapter(List<Crime> crimes) {
mCrimes = crimes;
}
#Override
public CrimeHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater layoutInflater = LayoutInflater.from(getActivity());
if (viewType==1) { layout = R.layout.list_item_crime_police;}
else { layout = R.layout.list_item_crime; }
return new CrimeHolder (layout, layoutInflater, parent);
}
#Override
public void onBindViewHolder(CrimeHolder holder, int position) {
Crime crime = mCrimes.get(position);
holder.bind(crime);
}
#Override
public int getItemCount() {
return mCrimes.size();
}
public int getItemViewType(int position) {
Crime crime = mCrimes.get(position);
return (crime.isRequiresPolice()) ? 1 : 0;
}
}
#Override
public void onResume() {
super.onResume();
updateUI();
}
private void updateUI() {
CrimeLab crimeLab = CrimeLab.get(getActivity());
List<Crime> crimes = crimeLab.getCrimes();
if (mAdapter == null) {
mAdapter = new CrimeAdapter(crimes);
mCrimeRecyclerView.setAdapter(mAdapter);
} else {
mAdapter.notifyDataSetChanged();
}
}
#Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == REQUEST_CRIME) {
// Обработка результата
}
}
public void returnResult() {
getActivity().setResult(Activity.RESULT_OK, null);
}
}
CrimePagerActivity.java
package com.bignerdranch.android.criminalintent;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentStatePagerAdapter;
import androidx.viewpager.widget.ViewPager;
import java.util.List;
import java.util.UUID;
public class CrimePagerActivity extends AppCompatActivity {
private static final String EXTRA_CRIME_ID = "com.bignerdranch.android.criminalintent.crime_id";
private ViewPager mViewPager;
private List<Crime> mCrimes;
MyAdapter mAdapter;
public static Intent newIntent(Context packageContext, UUID crimeId) {
Intent intent = new Intent(packageContext, CrimePagerActivity.class);
intent.putExtra(EXTRA_CRIME_ID, crimeId);
return intent;
}
#Override
protected void onCreate( Bundle savedInstanceState ) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_crime_pager);
UUID crimeId = (UUID) getIntent().getSerializableExtra(EXTRA_CRIME_ID);
mViewPager = (ViewPager) findViewById(R.id.crime_view_pager);
mCrimes = CrimeLab.get(this).getCrimes();
mAdapter = new MyAdapter(getSupportFragmentManager(),mCrimes);
mViewPager.setAdapter(mAdapter);
for (int i = 0; i < mCrimes.size(); i++) {
if (mCrimes.get(i).getId().equals(crimeId)) {
mViewPager.setCurrentItem(i);
break;
}
}
}
public static class MyAdapter extends FragmentStatePagerAdapter {
private List<Crime> mCrimesCopy;
public MyAdapter(FragmentManager fm, List<Crime> mCrimesParametr) {
//super(fm);
super(fm, BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT);
this.mCrimesCopy = mCrimesParametr;
}
#Override
public int getCount() {
return mCrimesCopy.size();
}
#Override
public Fragment getItem(int position) {
Crime crime = mCrimesCopy.get(position);
return CrimeFragment.newInstance(crime.getId());
}
}
}
fragment_crime_list.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.recyclerview.widget.RecyclerView
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/crime_recycler_view"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
fragment_crime.xml
<?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:layout_margin="16dp"
android:orientation="vertical">
<TextView
style="?android:listSeparatorTextViewStyle"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/crime_title_label"/>
<EditText
android:id="#+id/crime_title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="#string/crime_title_hint"
android:inputType=""
android:autofillHints="" />
<TextView
style="?android:listSeparatorTextViewStyle"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/crime_details_label"/>
<Button
android:id="#+id/crime_date"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
<CheckBox
android:id="#+id/crime_solved"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/crime_solved_label"/>
</LinearLayout>
list_item_crime_police.xml
<?xml version="1.0" encoding="utf-8"?>
<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:id="#+id/linearLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="#+id/crime_title"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
android:layout_marginEnd="8dp"
android:text="#string/crime_title"
android:textColor="#android:color/black"
android:textSize="18sp"
app:layout_constraintEnd_toStartOf="#+id/crime_solved"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/crime_date"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:text="#string/crime_date"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/crime_solved" />
<Button
android:id="#+id/call_police"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:layout_marginBottom="8dp"
android:text="#string/call_police"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/crime_date" />
<ImageView
android:id="#+id/crime_solved"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:layout_marginEnd="8dp"
android:layout_marginBottom="16dp"
android:contentDescription="#string/todo"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#drawable/ic_solved" />
</androidx.constraintlayout.widget.ConstraintLayout>
list_item_crime.xml
<?xml version="1.0" encoding="utf-8"?>
<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:id="#+id/linearLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="#+id/crime_title"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
android:layout_marginEnd="8dp"
android:text="#string/crime_title"
android:textColor="#android:color/black"
android:textSize="18sp"
app:layout_constraintEnd_toStartOf="#+id/crime_solved"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/crime_date"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:text="#string/crime_date"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/crime_solved" />
<ImageView
android:id="#+id/crime_solved"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:layout_marginEnd="8dp"
android:layout_marginBottom="16dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#drawable/ic_solved"
android:contentDescription="#string/todo" />
</androidx.constraintlayout.widget.ConstraintLayout>
activity_crime_pager.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.viewpager.widget.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/crime_view_pager"
android:layout_width="match_parent"
android:layout_height="match_parent">
</androidx.viewpager.widget.ViewPager>
activity_fragment.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="match_parent" />

I think the items in the RecyclerView are unordered because the references for views which are present in your list_item_crime_police.xml or list_item_crime.xml layout file is declared as class members of CrimeListFragment and not inside CrimeHolder class as :
public class CrimeListFragment extends Fragment {
// your other views and variables related declarations
// these are problematic declaration that keeps on being reused
private TextView mTitleTextView;
private TextView mDateTextView;
private ImageView mSolvedImageView;
private Button mButtonCallPolice;
// your other declarations
// your other code
}
That's why, the same view instances such as mTitleTextView, mDateTextView, mSolvedImageView, mButtonCallPolice, etc. are being reused for every CrimeHolder instances causing the unordering of the items in the list. Now, in order to fix this problem, you can simply move these lines to code to CrimeHolder class as class variable which would ensures that every new CrimeHolder instance will have separate instances of above-mentioned views as :
private class CrimeHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
// declare all of them here so there will be unique instances of these views for unique viewholder
private TextView mTitleTextView;
private TextView mDateTextView;
private ImageView mSolvedImageView;
private Button mButtonCallPolice;
public CrimeHolder(int layout, LayoutInflater inflater, ViewGroup parent ) {
View itemView = inflater.inflate(layout, parent, false));
super(itemView);
mTitleTextView = (TextView) itemView.findViewById(R.id.crime_title);
mDateTextView = (TextView) itemView.findViewById(R.id.crime_date);
mSolvedImageView = (ImageView) itemView.findViewById(R.id.crime_solved);
if (itemView.findViewById(R.id.call_police)!=null) {
mButtonCallPolice = (Button) itemView.findViewById(R.id.call_police);
}
itemView.setOnClickListener(this);
}
public void bind(Crime crime) {
mCrime = crime;
mTitleTextView.setText(mCrime.getTitle());
mDateFormat = DateFormat.format("EEE, MMM dd, yyyy", mCrime.getDate());
mDateTextView.setText(mDateFormat);
mSolvedImageView.setVisibility(mCrime.isSolved() ? View.VISIBLE :
View.GONE);
if(mCrime.isRequiresPolice()){
mButtonCallPolice.setEnabled(true);
}
}
#Override
public void onClick(View view) {
Intent intent = CrimePagerActivity.newIntent(getActivity(),
CrimeLab.get(requireActivity()).getCrimes().get((getAdapterPosition())).getId());
startActivityForResult(intent, REQUEST_CRIME);
}
}
It fixed my problem and I hope it will fix yours too.