Application that uses Radio button

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

    <TextView
        android:id="@+id/textView1"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="30dp"
        android:gravity="center_horizontal"
        android:textSize="22dp"
        android:text="Single Radio Buttons" />
    
    <!-- Default RadioButtons -->
    <RadioButton
        android:id="@+id/radioButton1"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:text="Radio Button 1"
        android:layout_marginTop="20dp"
        android:textSize="20dp" />
    
    <RadioButton
        android:id="@+id/radioButton2"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Radio Button 2"
        android:layout_marginTop="10dp"
        android:textSize="20dp" />
    
    <View
        android:layout_width="fill_parent"
        android:layout_height="1dp"
        android:layout_marginTop="20dp"
        android:background="#B8B894" />
    
    <TextView
        android:id="@+id/textView2"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="30dp"
        android:gravity="center_horizontal"
        android:textSize="22dp"
        android:text="Radio button inside RadioGroup" />
    
    <!-- Customized RadioButtons -->
    <RadioGroup
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/radioGroup">
        
        <RadioButton
            android:id="@+id/radioMale"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text=" Male"
            android:layout_marginTop="10dp"
            android:checked="false"
            android:textSize="20dp" />
        
        <RadioButton
            android:id="@+id/radioFemale"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text=" Female"
            android:layout_marginTop="20dp"
            android:checked="false"
            android:textSize="20dp" />
        
    </RadioGroup>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Show Selected"
        android:id="@+id/button"
        android:onClick="onclickbuttonMethod"
        android:layout_gravity="center_horizontal" />

</LinearLayout>

package com.example.myapplication;

import android.os.Bundle;
import android.view.View;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {
    RadioGroup radioGroup;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        radioGroup = (RadioGroup)findViewById(R.id.radioGroup);
    }

    public void onclickbuttonMethod(View view) {
        if (radioGroup.getCheckedRadioButtonId() == -1) {
            Toast.makeText(MainActivity.this, "Nothing selected", Toast.LENGTH_SHORT).show();
        } else {
            Toast.makeText(MainActivity.this, ((RadioButton) findViewById(radioGroup.getCheckedRadioButtonId())).getText(), Toast.LENGTH_SHORT).show();
        }
    }
}