MainActivity code

package com.example.myapplication.main;
import androidx.appcompat.app.AppCompatActivity;
import androidx.lifecycle.ViewModelProvider;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.os.Bundle;
import android.util.Log;
import com.example.myapplication.R;
import com.example.myapplication.model.ApiServiceProvider;
import com.example.myapplication.model.AppDatabase;
import com.example.myapplication.model.Student;
import com.example.myapplication.model.StudentRepository;
import java.util.List;
public class MainActivity extends AppCompatActivity {
    private static final String TAG = "MainActivity";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        MainViewModel model = new ViewModelProvider(this,
                new MainViewModelFactory(
                        new StudentRepository(
                                ApiServiceProvider.getApiService(),
                                AppDatabase.getAppDatabase(getApplicationContext())
                                        .studentDao()))).get(MainViewModel.class);
        model.getStudents().observe(this,students->{
            RecyclerView recyclerView =findViewById(R.id.rv_main);
            recyclerView.setLayoutManager(new LinearLayoutManager(this,RecyclerView.VERTICAL,false));
            StudentAdapter adapter = new StudentAdapter(students);
            recyclerView.setAdapter(adapter);
            Log.i(TAG, "onCreate: ");
        });
        model.getError().observe(this,error->{
        Log.e(TAG, "onCreate: ");
        });
    }
}

StudentAdapter Code

package com.example.myapplication.main;
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.example.myapplication.R;
import com.example.myapplication.model.Student;
import java.util.List;
public class StudentAdapter extends RecyclerView.Adapter<StudentAdapter.StudentViewHolder> {
    private List<Student> students;
    StudentAdapter(List<Student> students){
        this.students=students;
    }
    @NonNull
    @Override
    public StudentViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        return new StudentViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.item_student,parent,false));
    }
    @Override
    public void onBindViewHolder(@NonNull StudentViewHolder holder, int position) {
        holder.bind(students.get(position));
    }
    @Override
    public int getItemCount() {
        return students.size();
    }
    public class StudentViewHolder extends RecyclerView.ViewHolder{
        private TextView firstCharTv;
        private TextView fullNameTv;
        private TextView courseTv;
        private TextView scoreTv;
        public StudentViewHolder(@NonNull View itemView) {
            super(itemView);
            firstCharTv=itemView.findViewById(R.id.item_student_firstCharacter);
            fullNameTv=itemView.findViewById(R.id.item_student_fullName);
            courseTv=itemView.findViewById(R.id.item_student_course);
            scoreTv=itemView.findViewById(R.id.item_student_score);
        }
        public void bind(Student student){
            firstCharTv.setText(student.getFirstName().substring(0,1));
            fullNameTv.setText(student.getFirstName()+" "+student.getLastName());
            courseTv.setText(student.getCourse());
            scoreTv.setText(student.getScore());
        }
    }
}

سلام وقتت بخیر پارسا جان

ارور مربوط میشه به کد زیر و به این دلیل هست ما نمیتونیم integer رو به setText بدیم تا برامون روی ویو ست کنه.

scoreTv.setText(student.getScore());

که باید بنویسید

scoreTv.setText(String.valueOf(student.getScore()));

و ادپتر کامل شما خواهد شد

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 java.util.ArrayList;
import java.util.List;
public class StudentAdapter extends RecyclerView.Adapter<StudentAdapter.StudentViewHolder> {
    private List<Student> students = new ArrayList<>();
    public void addStudents(List<Student> students) {
        this.students.clear();
        this.students.addAll(students);
        notifyDataSetChanged();
    }
    @NonNull
    @Override
    public StudentViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        return new StudentViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.item_student, parent, false));
    }
    @Override
    public void onBindViewHolder(@NonNull StudentViewHolder holder, int position) {
        holder.bind(students.get(position));
    }
    @Override
    public int getItemCount() {
        return students.size();
    }
    public static class StudentViewHolder extends RecyclerView.ViewHolder {
        private TextView fullNameTv;
        private TextView courseTitleTv;
        private TextView scoreTv;
        private TextView firstCharacterTv;
        public StudentViewHolder(@NonNull View itemView) {
            super(itemView);
            fullNameTv = itemView.findViewById(R.id.tv_student_fullName);
            courseTitleTv = itemView.findViewById(R.id.tv_student_course);
            scoreTv = itemView.findViewById(R.id.tv_student_score);
            firstCharacterTv = itemView.findViewById(R.id.tv_student_firstCharacter);
        }
        public void bind(Student student) {
            fullNameTv.setText(student.getFirstName() + " " + student.getLastName());
            courseTitleTv.setText(student.getCourse());
            scoreTv.setText(String.valueOf(student.getScore()));
            firstCharacterTv.setText(student.getFirstName().substring(0, 1));
        }
    }
}