Develop an android application to create a Simple Calculator

activity_main.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"
    android:padding="10dp"
    android:gravity="center"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/tv1"
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:text="First Number"
        android:gravity="center"
        style="@android:style/TextAppearance.Large"/>

    <EditText android:id="@+id/etNum1"
        android:layout_width="200dp"
        android:layout_height="50dp"
        android:ems="10"
        android:hint="Enter number 1"
        android:layout_marginLeft="30dp"
        android:layout_toRightOf="@id/tv1"/>

    <TextView
        android:id="@+id/tv2"
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:text="Second Number"
        android:gravity="center"
        android:layout_below="@id/tv1"
        style="@android:style/TextAppearance.Large"/>

    <EditText android:id="@+id/etNum2"
        android:layout_width="200dp"
        android:layout_height="50dp"
        android:ems="10"
        android:hint="Enter number 2"
        android:layout_marginLeft="5dp"
        android:layout_toRightOf="@id/tv2"
        android:layout_below="@id/etNum1"/>

    <Button android:id="@+id/btnPlus"
        android:layout_width="70dp"
        android:layout_height="70dp"
        android:text="+"
        android:textSize="26sp"
        android:layout_below="@id/tv2"
        android:layout_marginTop="30dp"
        android:layout_marginLeft="50dp"
        android:onClick="add"/>

    <Button android:id="@+id/btnMinus"
        android:layout_width="70dp"
        android:layout_height="70dp"
        android:text="-"
        android:textSize="26sp"
        android:layout_below="@id/tv2"
        android:layout_toRightOf="@id/btnPlus"
        android:layout_marginTop="30dp"
        android:onClick="subtract"/>

    <Button android:id="@+id/btnMul"
        android:layout_width="70dp"
        android:layout_height="70dp"
        android:text="*"
        android:textSize="26sp"
        android:layout_below="@id/tv2"
        android:layout_toRightOf="@id/btnMinus"
        android:layout_marginTop="30dp"
        android:onClick="multiply"/>

    <Button android:id="@+id/btnDiv"
        android:layout_width="70dp"
        android:layout_height="70dp"
        android:text="/"
        android:textSize="26sp"
        android:layout_below="@id/tv2"
        android:layout_toRightOf="@id/btnMul"
        android:layout_marginTop="30dp"
        android:onClick="divide"/>

    <TextView android:id="@+id/tvResult"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/btnPlus"
        android:textSize="26sp"
        android:layout_marginTop="50dp"/>

</RelativeLayout>

MainActivity.java

package com.example.calculator;
import android.support.v7.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 {

    EditText etNum1, etNum2;
    Button btnPlus, btnMinus, btnMul, btnDiv;
    TextView tvResult;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        etNum1 = findViewById(R.id.etNum1);
        etNum2 = findViewById(R.id.etNum2);
        btnPlus = findViewById(R.id.btnPlus);
        btnMinus = findViewById(R.id.btnMinus);
        btnMul = findViewById(R.id.btnMul);
        btnDiv = findViewById(R.id.btnDiv);
        tvResult = findViewById(R.id.tvResult);
    }

    public void add(View view) {

        double n1 = Double.parseDouble(etNum1.getText().toString());
        double n2 = Double.parseDouble(etNum2.getText().toString());
        double result = n1 + n2;
        tvResult.setText("Addition is: " + result);
    }

    public void subtract(View view) {

        double n1 = Double.parseDouble(etNum1.getText().toString());
        double n2 = Double.parseDouble(etNum2.getText().toString());
        double result = n1 - n2;
        tvResult.setText("Subtraction is: " + result);
    }

    public void multiply(View view) {

        double n1 = Double.parseDouble(etNum1.getText().toString());
        double n2 = Double.parseDouble(etNum2.getText().toString());
        double result = n1 * n2;
        tvResult.setText("Multiplication is: " + result);
    }

    public void divide(View view) {
      
        double n1 = Double.parseDouble(etNum1.getText().toString());
        double n2 = Double.parseDouble(etNum2.getText().toString());
        double result = n1 / n2;
        tvResult.setText("Division is: " + result);
    }
}

OUTPUT