using checkbox with fragment result close app

I'm using Android Studio 3.5 and this issue appear when use it in fragment .. I'm try to use checkbox on fragment but when checked when run on mobile (the application close and give error ) i don't know from where the problem is .

Anyone can help me to solve this issue .. thanks note : I built bottom navigation and this fragment that show on fragment not in activity . thanks :

othersFragment:

public class othersActivity extends Fragment {

ArrayList<Integer> selection = new ArrayList<Integer>();

CheckBox send_it ;
Button btn_totalPrice , btn_submit;
TextView total_price;


public othersActivity (){

}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.activity_others, container, false);

//ini checkBox
send_it = v.findViewById(R.id.ch_sendITE);

//ini btn (submit & total price) and Textview
btn_totalPrice = v.findViewById(R.id.btn_submit);
btn_submit = v.findViewById(R.id.btn_totalPrice);

total_price = v.findViewById(R.id.t_totalPrice);

return v;
}


public void selectedItem(View view){
boolean checked = ((CheckBox) view).isChecked();

switch (view.getId()){
        case R.id.ch_sendITE:
            if(checked){
                selection.add(5);
            }else{
                selection.remove(Integer.valueOf("5"));
            }
            break;

    }

}

public void final_price(View v){

    String final_price  = "";
    double sum = 0;
    for(int i=0;i<selection.size(); i++){
        sum = sum + selection.get(i);
    }
    String res = String.valueOf(sum);
    final_price = res;
    total_price.setText(final_price);

}

}

Activity_others.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"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".fragments.othersActivity">

<RelativeLayout
    android:id="@+id/banner"
    android:layout_width="match_parent"
    android:layout_height="200dp"
    android:background="@drawable/banner3">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:fontFamily="casual"
        android:text="e - Request"
        android:textColor="@color/colorDarkBlue"
        android:textSize="50dp"
        android:textStyle="bold" />

</RelativeLayout>

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_below="@+id/banner"
    android:orientation="vertical"
    android:paddingLeft="20dp">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="30dp"
        android:layout_marginBottom="20dp"
        android:text="Please select your item:"
        android:textColor="@color/colorBlack"
        android:textSize="30dp"
        android:textStyle="bold" />

    <CheckBox
        android:onClick="selectedItem"
        android:id="@+id/ch_sendITE"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:text="@string/send_ITE"
        android:textSize="20dp" />

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="90dp"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/show_totalPrice"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Total price : "
            android:textSize="20dp" />

        <TextView
            android:id="@+id/t_totalPrice"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text=" 0.0 "
            android:textSize="20dp" />

        <TextView
            android:id="@+id/K.d_totalPrice"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text=" K.D "
            android:textSize="20dp" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:layout_marginTop="25dp"
        android:orientation="horizontal">

        <Button
            android:onClick="final_price"
            android:id="@+id/btn_totalPrice"
            android:layout_width="130dp"
            android:layout_height="wrap_content"
            android:background="@drawable/btn_log_regist"
            android:text="Total price"
            android:textColor="@color/colorWhite" />

        <Button
            android:id="@+id/btn_submit"
            android:layout_width="130dp"
            android:layout_height="wrap_content"
            android:layout_marginLeft="10dp"
            android:background="@drawable/btn_log_regist"
            android:text="Submit"
            android:textColor="@color/colorWhite" />

    </LinearLayout>


</LinearLayout>

</RelativeLayout>