Селективная кнопка не отображается

Question

RadioButton не отображается. Согласно моему коду, должен появиться переключатель с именем CSE, но он не виден, потому что во время создания базы данных я добавляю один курс с подробным названием CSE в DatabaseHelper. java. Должен появиться хотя бы один переключатель.

Я не понимаю, в чем проблема.

CreateStudent. java

EditText firstnm,lastnm,email,contact;
Button add;
RadioGroup radioGroup;

DatabaseHelper db;

@RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR1)
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_create_student);

db=new DatabaseHelper(this);

Toolbar toolbar = findViewById(R.id.tool);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setDisplayShowHomeEnabled(true);

toolbar.setNavigationOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        Intent intent=new Intent(CreateStudent.this,Home.class);
        startActivity(intent);
    }
});

firstnm=findViewById(R.id.teacherfirstnm);
lastnm=findViewById(R.id.teacherlastnm);
email=findViewById(R.id.teacheremail);
contact=findViewById(R.id.teachercontact);
add=findViewById(R.id.addstudent);
radioGroup=findViewById(R.id.radio);


ArrayList<String> coursenm = new ArrayList<String>(db.getCourseName());


if (coursenm!=null)
{
    RadioButton[] rb=new RadioButton[coursenm.size()];

    for (int i=0;i<rb.length;i++){
        rb[i]=new RadioButton(this);
    }
    for (int i=0;i<coursenm.size();i++){
        rb[i].setText(coursenm.get(i).toString());
        rb[i].setId(Integer.parseInt(coursenm.get(i)));
        radioGroup.addView(rb[i]);
    }
}


add.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {

        String first=firstnm.getText().toString().trim();
        String last=lastnm.getText().toString().trim();
        String emailid=email.getText().toString().trim();
        String contactno=contact.getText().toString().trim();

        int selectedRB=radioGroup.getCheckedRadioButtonId();
        RadioButton selectedRButton=(RadioButton) findViewById(selectedRB);
        final String selectRBText=selectedRButton.getText().toString();

        if (first == null || last == null || emailid == null || contactno == null || selectRBText==null){
            Toast.makeText(CreateStudent.this, "All Fields are Required", Toast.LENGTH_SHORT).show();
            firstnm.setText("");
            lastnm.setText("");
            email.setText("");
            contact.setText("");
            radioGroup.clearCheck();
        }
        else {
            Long val=db.addStudent(first,last,emailid,contactno,selectRBText);
            if(val > 0) {
                Toast.makeText(CreateStudent.this, " You Have Added Successfully ", Toast.LENGTH_LONG).show();
                startActivity(new Intent(CreateStudent.this, Home.class));
            }
            else{
                Toast.makeText(CreateStudent.this, "  Error", Toast.LENGTH_LONG).show();
            }
        }

    }
});

cratestudent. 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=".CreateStudent">

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

    <androidx.core.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@id/tool">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="#0F504848"
            android:orientation="vertical">

            <com.google.android.material.textfield.TextInputLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginLeft="5dp"
                android:layout_marginRight="5dp"
                android:layout_marginTop="20dp"
                android:textColorHint="#FE22B3E8">

                <EditText
                    android:id="@+id/teacherfirstnm"
                    android:layout_width="match_parent"
                    android:layout_height="50dp"
                    android:background="@drawable/textinputborder"
                    android:ems="10"
                    android:hint="First Name"
                    android:inputType="textPersonName"
                    android:shadowColor="#000" />

            </com.google.android.material.textfield.TextInputLayout>

            <com.google.android.material.textfield.TextInputLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:textColorHint="#FE22B3E8"
                android:layout_marginLeft="5dp"
                android:layout_marginRight="5dp">

                <EditText
                    android:id="@+id/teacherlastnm"
                    android:layout_width="match_parent"
                    android:layout_height="50dp"
                    android:ems="10"
                    android:background="@drawable/textinputborder"
                    android:hint="Last Name"
                    android:inputType="textPersonName" />

            </com.google.android.material.textfield.TextInputLayout>

            <com.google.android.material.textfield.TextInputLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginLeft="5dp"
                android:layout_marginRight="5dp"
                android:textColorHint="#FE22B3E8">

                <EditText
                    android:id="@+id/teachercontact"
                    android:background="@drawable/textinputborder"
                    android:layout_width="match_parent"
                    android:layout_height="50dp"
                    android:ems="10"
                    android:hint="Contact Name"
                    android:inputType="number" />

            </com.google.android.material.textfield.TextInputLayout>

            <com.google.android.material.textfield.TextInputLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:textColorHint="#FE22B3E8"
                android:layout_marginLeft="5dp"
                android:layout_marginRight="5dp">

                <EditText
                    android:id="@+id/teacheremail"
                    android:layout_width="match_parent"
                    android:layout_height="50dp"
                    android:ems="10"
                    android:background="@drawable/textinputborder"
                    android:hint="Email Id"
                    android:inputType="textEmailAddress" />

            </com.google.android.material.textfield.TextInputLayout>

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginTop="20dp"
                android:textColor="#1B1A1A"
                android:layout_marginLeft="5dp"
                android:layout_marginRight="5dp"
                android:text="Select Course : "
                android:textSize="25sp"
                android:textStyle="bold" />

            <androidx.core.widget.NestedScrollView
                    android:layout_width="match_parent"
                    android:layout_height="100dp"
                    android:layout_marginTop="20dp">

                <LinearLayout
                    android:id="@+id/layout"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_marginLeft="5dp"
                    android:layout_marginRight="5dp"
                    android:orientation="vertical">

                        <RadioGroup
                            android:layout_width="match_parent"
                            android:id="@+id/radio"
                            android:background="@drawable/textinputborder"
                            android:layout_height="wrap_content">

                        </RadioGroup>

                    </LinearLayout>

                </androidx.core.widget.NestedScrollView>

            <Button
                android:id="@+id/addstudent"
                android:layout_width="match_parent"
                android:layout_height="50dp"
                android:layout_marginTop="20dp"
                android:text="Add Student"
                android:layout_marginBottom="20dp"
                android:background="#FE22B3E8"/>

        </LinearLayout>

    </androidx.core.widget.NestedScrollView>

</RelativeLayout>

DatabaseHelper. java

    public String current_email;
    public String current_user;

    public static final String DATABASE_NAME = "Attendence.db";

    public static final String TABLE_NAME = "user";
    public static final String USER_COL_1 = "ID";
    public static final String USER_COL_2 = "fullname";
    public static final String USER_COL_3 = "emailid";
    public static final String USER_COL_4 = "username";
    public static final String USER_COL_5 = "password";
    public static final String USER_COL_6 = "account_type";

    public static final String TABLE_NAME2 ="student";
    public static final String STUDENT_COL1 = "ID";
    public static final String STUDENT_COL2 = "firstname";
    public static final String STUDENT_COL3 = "lastname";
    public static final String STUDENT_COL4 = "contactno";
    public static final String STUDENT_COL5 = "emailid";
    public static final String STUDENT_COL6 = "course";

    public static final String TABLE_NAME3 ="teacher";
    public static final String TEACHER_COL1 = "ID";
    public static final String TEACHER_COL2 = "firstname";
    public static final String TEACHER_COL3 = "lastname";
    public static final String TEACHER_COL4 = "contactno";
    public static final String TEACHER_COL5 = "emailid";

    public static final String TABLE_NAME4 ="course";
    public static final String COURSE_COL1 = "ID";
    public static final String COURSE_COL2 = "coursecode";
    public static final String COURSE_COL3 = "coursename";
    public static final String COURSE_COL4 = "teachername";



    public DatabaseHelper(@Nullable Context context) {
        super(context, DATABASE_NAME, null, 1);
    }


    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table " + TABLE_NAME + " (id integer primary key autoincrement ,fullname text,emailid text,username text,password text , account_type text)");

        db.execSQL("create table " + TABLE_NAME2 + " ( id integer primary key autoincrement , firstname text, lastname text, contactno integer, emailid text , course text ) ");

        db.execSQL("create table " + TABLE_NAME3 + " ( id integer primary key autoincrement , firstname text, lastname text,contactno integer ,  emailid text ) ");

        db.execSQL("create table " + TABLE_NAME4 + " (id integer primary key autoincrement ,  coursecode text, coursename text, teachername text ) ");
        db.execSQL("insert into " + TABLE_NAME4 +"(coursecode , coursename , teachername ) values ('CSE','CSE','Pradeep')");

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL(" DROP TABLE IF EXISTS " + TABLE_NAME);
        onCreate(db);

        db.execSQL(" DROP TABLE IF EXISTS " + TABLE_NAME2);
        onCreate(db);

        db.execSQL(" DROP TABLE IF EXISTS " + TABLE_NAME3);
        onCreate(db);

        db.execSQL(" DROP TABLE IF EXISTS " + TABLE_NAME4);
        onCreate(db);

    }


    public Boolean checkUser(String user, String pwd , String acc_type) {
        String[] columns = {USER_COL_1};
        SQLiteDatabase db = this.getReadableDatabase();
        String selection = USER_COL_4 + "=?" + " and " + USER_COL_5 + "=?" + " and " + USER_COL_6 + "=?";
        String[] selectionArgs = {user, pwd , acc_type};
        Cursor cursor = db.query(TABLE_NAME, columns, selection, selectionArgs, null, null, null);
        int count = cursor.getCount();

        cursor.close();
        db.close();

        if (count > 0) {
            current_user = user;
            return true;
        }
        else
            return false;
    }

    public Long addUser(String full_nm,  String email_id,  String user,   String pwd ,  String acc_type) {
        SQLiteDatabase db=this.getWritableDatabase();
        ContentValues c=new ContentValues();
        c.put(USER_COL_2,full_nm);
        c.put(USER_COL_3,email_id);
        c.put(USER_COL_4,user);
        c.put(USER_COL_5,pwd);
        c.put(USER_COL_6,acc_type);

        Long res=db.insert(TABLE_NAME,null,c);
        db.close();

        return res;
    }

    public String getCurrentUser()
    {
        return current_user;
    }

    public String getCurrentUserEmail()
    {
        SQLiteDatabase db = this.getReadableDatabase();
        String selectquery="SELECT " + USER_COL_3 +" FROM " + TABLE_NAME + " WHERE " + USER_COL_4 +" = '" + current_user +"'";
        Cursor cursor=db.rawQuery(selectquery,null);
        cursor.moveToFirst();
        current_email=cursor.getString(cursor.getColumnIndex(USER_COL_3));
        cursor.close();
        return current_email;

    }


    public Long addStudent(String first, String last, String emailid, String contactno , String course) {

        SQLiteDatabase db=this.getWritableDatabase();
        ContentValues c=new ContentValues();
        c.put(STUDENT_COL2,first);
        c.put(STUDENT_COL3,last);
        c.put(STUDENT_COL4,contactno);
        c.put(STUDENT_COL5,emailid);
        c.put(STUDENT_COL6,course);

        Long res=db.insert(TABLE_NAME2,null,c);
        db.close();

        return res;

    }

    public Long addTeacher(String first, String last, String contactno, String emailid) {
        SQLiteDatabase db=this.getWritableDatabase();
        ContentValues c=new ContentValues();
        c.put(TEACHER_COL2,first);
        c.put(TEACHER_COL3,last);
        c.put(TEACHER_COL4,contactno);
        c.put(TEACHER_COL5,emailid);

        Long res=db.insert(TABLE_NAME3,null,c);
        db.close();

        return res;
    }

    public String[] getTeacherfirstnm() {
        SQLiteDatabase db = this.getReadableDatabase();
        String selectquery="SELECT * FROM " + TABLE_NAME3 ;
        Cursor res=db.rawQuery(selectquery,null);
        int count=res.getColumnCount();
        String[] array = new String[count];
        res.moveToFirst();
        while (res.isAfterLast()){
            int i=1;
            array[i]=(res.getString(res.getColumnIndex(TEACHER_COL2)));
            i++;
            res.moveToNext();
        }
        res.close();
        return array;
    }

    public String[] getTeacherlastnm() {
        SQLiteDatabase db = this.getReadableDatabase();
        String selectquery="SELECT * FROM " + TABLE_NAME3 ;
        Cursor res=db.rawQuery(selectquery,null);
        int count=res.getColumnCount();
        String[] array = new String[count];
        res.moveToFirst();
        while (res.isAfterLast()){
            int i=1;
            array[i]=(res.getString(res.getColumnIndex(TEACHER_COL3)));
            i++;
            res.moveToNext();
        }
        res.close();
        return array;
    }

    public String[] getTeacherContact() {
        SQLiteDatabase db = this.getReadableDatabase();
        String selectquery="SELECT * FROM " + TABLE_NAME3 ;
        Cursor res=db.rawQuery(selectquery,null);
        int count=res.getColumnCount();
        String[] array = new String[count];
        res.moveToFirst();
        while (res.isAfterLast()){
            int i=1;
            array[i]=(res.getString(res.getColumnIndex(TEACHER_COL4)));
            i++;
            res.moveToNext();
        }
        res.close();
        return array;
    }

    public String[] getStudentFirstName() {
        SQLiteDatabase db = this.getReadableDatabase();
        String selectquery="SELECT * FROM " + TABLE_NAME2 ;
        Cursor res=db.rawQuery(selectquery,null);
        int count=res.getColumnCount();
        String[] array = new String[count];
        res.moveToFirst();
        while (res.isAfterLast()){
            int i=1;
            array[i]=(res.getString(res.getColumnIndex(STUDENT_COL2)));
            i++;
            res.moveToNext();
        }
        res.close();
        return array;
    }
    public String[] getStudentLastName() {
        SQLiteDatabase db = this.getReadableDatabase();
        String selectquery="SELECT * FROM " + TABLE_NAME2 ;
        Cursor res=db.rawQuery(selectquery,null);
        int count=res.getColumnCount();
        String[] array = new String[count];
        res.moveToFirst();
        while (res.isAfterLast()){
            int i=1;
            array[i]=(res.getString(res.getColumnIndex(STUDENT_COL3)));
            i++;
            res.moveToNext();
        }
        res.close();
        return array;
    }

    public String[] getStudentCourse() {
        SQLiteDatabase db = this.getReadableDatabase();
        String selectquery="SELECT * FROM " + TABLE_NAME2 ;
        Cursor res=db.rawQuery(selectquery,null);
        int count=res.getColumnCount();
        String[] array = new String[count];
        res.moveToFirst();
        while (res.isAfterLast()){
            int i=1;
            array[i]=(res.getString(res.getColumnIndex(STUDENT_COL6)));
            i++;
            res.moveToNext();
        }
        res.close();
        return array;
    }

    public Long addCourse(String code, String name, String teachernm) {
        SQLiteDatabase db=this.getWritableDatabase();
        ContentValues c=new ContentValues();
        c.put(COURSE_COL2,code);
        c.put(COURSE_COL3,name);
        c.put(COURSE_COL4,teachernm);

        Long res=db.insert(TABLE_NAME4,null,c);
        db.close();

        return res;
    }

    public ArrayList<String> getCourseName() {
        SQLiteDatabase db = this.getReadableDatabase();
        String selectquery="SELECT * FROM " + TABLE_NAME4 ;
        Cursor res=db.rawQuery(selectquery,null);

        ArrayList<String> array=new ArrayList<>();

        if (res!=null && res.moveToFirst()) {

            while (res.isAfterLast()) {
                array.add(res.getString(res.getColumnIndex(COURSE_COL3)));
                res.moveToNext();
            }
            res.close();
            return array;
        }
        else {
            return null;
        }
    }
    public String[] getCourseCode() {
        SQLiteDatabase db = this.getReadableDatabase();
        String selectquery="SELECT * FROM " + TABLE_NAME4 ;
        Cursor res=db.rawQuery(selectquery,null);
        int count=res.getColumnCount();
        String[] array = new String[count];
        res.moveToFirst();
        while (res.isAfterLast()){
            int i=1;
            array[i]=(res.getString(res.getColumnIndex(COURSE_COL2)));
            i++;
            res.moveToNext();
        }
        res.close();
        return array;
    }

}