В cardview с радиогруппой в списке уже отмечены некоторые радиокнопки

Я создал cardview с радиогруппой в android, здесь я делаю систему приема учеников, я уже сделал бэкэнд, и список учеников приходит правильно и отображается в карточках, но проблема в настоящее время или отсутствие отметки ученика, у меня была использовал радиогруппу по 4 радиокнопки в каждой карте. Но некоторые радиокнопки уже проверены, и когда я прокручиваю, то отмеченное положение радиокнопки также меняется .: - код для каждой отдельной карты

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    card_view:cardCornerRadius="5dp"

    card_view:cardUseCompatPadding="true" >

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="5dp" >

        <TextView
            android:id="@+id/tvName"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentTop="true"
            android:text="name"
            android:textColor="@android:color/black"
            android:textSize="18sp" />

        <TextView
            android:id="@+id/tvEmailId"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@id/tvName"
            android:text="email"
            android:textColor="@android:color/black"
            android:textSize="18sp" />
<RadioGroup android:id="@+id/rg"
    android:layout_alignParentRight="true"
    android:layout_centerVertical="true"

    android:layout_width="wrap_content"
    android:layout_height="wrap_content">


        <RadioButton
            android:id="@+id/chkSelected"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentRight="true"
            android:layout_centerVertical="true"
            android:text="A"
            android:checked="false">


        </RadioButton>

        <RadioButton
            android:id="@+id/chkSelected2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginRight="64dp"
            android:layout_marginEnd="64dp"
            android:layout_centerVertical="true"
            android:layout_toLeftOf="@+id/chkSelected"
            android:layout_toStartOf="@+id/chkSelected"
            android:text="P"
            android:checked="false">


        </RadioButton>

</RadioGroup>

    </RelativeLayout>

</android.support.v7.widget.CardView>

и код для checkboxsample.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">

    <LinearLayout
        android:layout_width="fill_parent"
        android:orientation="horizontal"
        android:gravity="center"
        android:layout_height="wrap_content">

        <Button
            android:layout_width="wrap_content"
            android:text="Check All"
            android:layout_marginRight="7dip"
            android:id="@+id/btnCheckAll"
            android:layout_height="wrap_content">
        </Button>
        <Button
            android:layout_width="wrap_content"
            android:text="Clear All"
            android:id="@+id/btnClearAll"
            android:layout_height="wrap_content">
        </Button>
    </LinearLayout>

    <ListView
        android:layout_width="fill_parent"
        android:id="@+id/lvCheckBox"
        android:fadingEdge="none"
        android:cacheColorHint="@null"
        android:layout_height="fill_parent">
    </ListView>
</LinearLayout>

код для activity_main.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:orientation="vertical" >

    <include
        android:id="@+id/toolbar"
        layout="@layout/toolbar" />

    <android.support.v7.widget.RecyclerView
        android:id="@+id/my_recycler_view"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_margin="5dp"
        android:layout_weight="1"
        android:scrollbars="vertical" />

    <Button
        android:id="@+id/btnShow"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="5dp"
        android:text="Show Selected"
        android:background="#00796B" 
        android:textColor="@color/TextPrimaryColor"/>

</LinearLayout>

код для student.java

package com.example.administrator.cardviewcheckbok;

import java.io.Serializable;

public class Student implements Serializable {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    private String name;

    private String emailId;

    private boolean isSelected;

    public Student() {

    }

    public Student(String name, String emailId) {

        this.name = name;
        this.emailId = emailId;

    }

    public Student(String name, String emailId, boolean isSelected) {

        this.name = name;
        this.emailId = emailId;
        this.isSelected = isSelected;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmailId() {
        return emailId;
    }

    public void setEmailId(String emailId) {
        this.emailId = emailId;
    }

    public boolean isSelected() {
        return isSelected;
    }

    public void setSelected(boolean isSelected) {
        this.isSelected = isSelected;
    }

}

код для cardviewdataadapter.java

package com.example.administrator.cardviewcheckbok;

import java.util.List;

import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;

import android.view.ViewGroup;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.CompoundButton.OnCheckedChangeListener;

public class CardViewDataAdapter extends
        RecyclerView.Adapter<CardViewDataAdapter.ViewHolder> {

    private List<Student> stList;

    public CardViewDataAdapter(List<Student> students) {
        this.stList = students;

    }

    // Create new views
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent,
            int viewType) {
        // create a new view
        View itemLayoutView = LayoutInflater.from(parent.getContext()).inflate(
                R.layout.cardview_row, null);

        // create ViewHolder

        ViewHolder viewHolder = new ViewHolder(itemLayoutView);

        return viewHolder;
    }

    @Override
    public void onBindViewHolder(ViewHolder viewHolder, int position) {

        final int pos = position;

        viewHolder.tvName.setText(stList.get(position).getName());

        viewHolder.tvEmailId.setText(stList.get(position).getEmailId());

        viewHolder.chkSelected.setSelected(stList.get(position).isSelected());

        viewHolder.chkSelected.setTag(stList.get(position));
////new checkselected2

        viewHolder.chkSelected2.setSelected(stList.get(position).isSelected());

        viewHolder.chkSelected2.setTag(stList.get(position));

viewHolder.checkrgg.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        RadioGroup rgg=(RadioGroup)v;
int selbutid=rgg.getCheckedRadioButtonId();

    RadioButton rb= (RadioButton) rgg.getChildAt(selbutid);
Toast.makeText(v.getContext(),""+rb.getText()+"",Toast.LENGTH_LONG).show();

    }
});

        viewHolder.chkSelected.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                RadioButton cb = (RadioButton) v;

                Student contact = (Student) cb.getTag();

                contact.setSelected(cb.isSelected());
                stList.get(pos).setSelected(cb.isSelected());

    /*          Toast.makeText(
                        v.getContext(),
                        "Clicked on Checkbox: " + "" + pos + cb + " is "
                                + cb.isSelected(), Toast.LENGTH_LONG).show();
    */
                    }

            });


        viewHolder.chkSelected2.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                RadioButton cb = (RadioButton) v;

                Student contact = (Student) cb.getTag();

                contact.setSelected(cb.isSelected());
                stList.get(pos).setSelected(cb.isSelected());
/*
                Toast.makeText(
                        v.getContext(),
                        "2222222Clicked on Checkbox: "+""+pos +cb + " is "
                                + cb.isSelected(), Toast.LENGTH_LONG).show();
                */
                    }
        });



    }

    // Return the size arraylist
    @Override
    public int getItemCount() {
        return stList.size();
    }

    public static class ViewHolder extends RecyclerView.ViewHolder {

        private final RadioGroup checkrgg;
        public TextView tvName;
        public TextView tvEmailId;

        public RadioButton chkSelected,chkSelected2;

        public Student singlestudent;

        public ViewHolder(View itemLayoutView) {
            super(itemLayoutView);

            tvName = (TextView) itemLayoutView.findViewById(R.id.tvName);

            tvEmailId = (TextView) itemLayoutView.findViewById(R.id.tvEmailId);
            chkSelected = (RadioButton) itemLayoutView
                    .findViewById(R.id.chkSelected);

            ///here putted code
            chkSelected2 = (RadioButton) itemLayoutView
                    .findViewById(R.id.chkSelected2);
////
            checkrgg=(RadioGroup)itemLayoutView.findViewById(R.id.rg);

        }

    }

    // method to access in activity after updating selection
    public List<Student> getStudentist() {
        return stList;
    }

}

код для cardviewactivity.java

package com.example.administrator.cardviewcheckbok;

import java.util.ArrayList;
import java.util.List;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class CardViewActivity extends ActionBarActivity {

    private Toolbar toolbar;

    private RecyclerView mRecyclerView;
    private RecyclerView.Adapter mAdapter;
    private RecyclerView.LayoutManager mLayoutManager;

    private List<Student> studentList;

    private Button btnSelection;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        toolbar = (Toolbar) findViewById(R.id.toolbar);
        btnSelection = (Button) findViewById(R.id.btnShow);

        studentList = new ArrayList<Student>();

        for (int i = 1; i <= 15; i++) {
            Student st = new Student("Student " + i, "androidstudent" + i
                    + "@gmail.com", false);

            studentList.add(st);
        }

        if (toolbar != null) {
            setSupportActionBar(toolbar);
            getSupportActionBar().setTitle("Android Students");

        }

        mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);

        // use this setting to improve performance if you know that changes
        // in content do not change the layout size of the RecyclerView
        mRecyclerView.setHasFixedSize(true);

        // use a linear layout manager
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));

        // create an Object for Adapter
        mAdapter = new CardViewDataAdapter(studentList);

        // set the adapter object to the Recyclerview
        mRecyclerView.setAdapter(mAdapter);

        btnSelection.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                String data = "";
                List<Student> stList = ((CardViewDataAdapter) mAdapter)
                        .getStudentist();

                for (int i = 0; i < stList.size(); i++) {
                    Student singleStudent = stList.get(i);
                    if (singleStudent.isSelected() == true) {

                        data = data + "\n" + singleStudent.getName().toString();
                        /*
                         * Toast.makeText( CardViewActivity.this, " " +
                         * singleStudent.getName() + " " +
                         * singleStudent.getEmailId() + " " +
                         * singleStudent.isSelected(),
                         * Toast.LENGTH_SHORT).show();
                         */

                ////
                                                }

                }

                Toast.makeText(CardViewActivity.this,
                        "Selected Students: \n" + data, Toast.LENGTH_LONG)
                        .show();
            }
        });

    }

}

Пожалуйста, это большая проблема. На самом деле, если мы делаем это с помощью списка, то также возникает такая же ошибка, поэтому попросите помощи от сообщества, чтобы дать некоторые предложения по этой проблеме. "просмотр карточек с радиогруппой в списке"