Adds numbers by taking input from 2 EditTexts and displays result in TextView

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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"
    android:background="#FAFA"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/textview1"
        android:layout_width="wrap_content"
        android:layout_height="46dp"
        android:text="Adding Two Numbers"
        android:textAlignment="center"
        android:textSize="30sp"
        android:textStyle="bold"
        app:layout_constraintBottom_toTopOf="@+id/num1"
        app:layout_constraintHorizontal_bias="0.495"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.366" />

    <EditText
        android:id="@+id/num1"
        android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="60dp"
        android:hint="Enter First Number"
        android:inputType="numberDecimal"
        android:textAlignment="center"
        android:textColorHint="#78909C"
        android:textSize="25sp"
        android:textStyle="bold"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.513"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textview1" />

    <EditText
        android:id="@+id/num2"
        android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="144dp"
        android:hint="Enter Second Number"
        android:inputType="numberDecimal"
        android:textAlignment="center"
        android:textSize="25sp"
        android:textStyle="bold"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.504"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/num1" />

    <TextView
        android:id="@+id/result"
        android:layout_width="297dp"
        android:layout_height="63dp"
        android:layout_marginTop="108dp"
        android:hint="Result"
        android:textAlignment="center"
        android:textColorHint="#78909C"
        android:textSize="25sp"
        android:textStyle="bold"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/num2" />

    <Button
        android:id="@+id/button"
        android:layout_width="182dp"
        android:layout_height="50dp"
        android:text="Click to Sum"
        android:textAllCaps="false"
        android:textStyle="bold"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/result" />

</androidx.constraintlayout.widget.ConstraintLayout>

AddTwoNumbers.java

package com.example.addtwonumbers;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

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

    // Declaring variables
        EditText num1 = findViewById(R.id.num1);
        EditText num2 = findViewById(R.id.num2);
        TextView result = findViewById(R.id.result);
        Button button = findViewById(R.id.button);

        button.setOnClickListener(new View.OnClickListener(){
            public void onClick(View view){
                double value1 = Double.parseDouble(num1.getText().toString());
                double value2 = Double.parseDouble(num2.getText().toString());
                double sum = value1 + value2;
                result.setText(Double.toString(sum));
            }
        });

    }
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.addtwonumbers">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.AddTwoNumbers">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>