Addition of two numbers in Android

This is a basic program for Addition of two numbers in Android

Steps to add two numbers

Create a new Android project in Android Studio.
Open the activity_main.xml file and add two EditText or NumberText views for the user to input the numbers and a Button view for the user to initiate the addition process.
In the MainActivity.java file, declare the two EditText views and the Button view as class-level variables.
In the onCreate() method of the MainActivity.java file, initialize the EditText views and the Button view by finding them by their respective IDs.
Set an OnClickListener on the Button view to listen for when the user clicks it.
In the onClick() method of the OnClickListener, get the text from the EditText views, convert them to integers, add them together, and display the result in a Toast message or in a TextView on the screen.

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"
    tools:context=".MainActivity">
    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="38dp"
        android:text="Addition of two numbers"
        android:textSize="34sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.496"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_wrapBehaviorInParent="horizontal_only" />
    <Button
        android:id="@+id/button"
        android:layout_width="295dp"
        android:layout_height="65dp"
        android:layout_marginTop="268dp"
        android:text="ADD"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.491"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:toggleCheckedStateOnClick="false" />
    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="368dp"
        android:text="Sum :"
        android:textSize="34sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.199"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
    <EditText
        android:id="@+id/editTextNumber"
        android:layout_width="296dp"
        android:layout_height="62dp"
        android:layout_marginTop="108dp"
        android:ems="10"
        android:inputType="number"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.495"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
    <EditText
        android:id="@+id/editTextNumber2"
        android:layout_width="295dp"
        android:layout_height="58dp"
        android:layout_marginTop="196dp"
        android:ems="10"
        android:inputType="number"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.491"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

<?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"

tools:context=".MainActivity">

<TextView

android:id="@+id/textView"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_marginTop="38dp"

android:text="Addition of two numbers"

android:textSize="34sp"

app:layout_constraintEnd_toEndOf="parent"

app:layout_constraintHorizontal_bias="0.496"

app:layout_constraintStart_toStartOf="parent"

app:layout_constraintTop_toTopOf="parent"

app:layout_wrapBehaviorInParent="horizontal_only" />

<Button

android:id="@+id/button"

android:layout_width="295dp"

android:layout_height="65dp"

android:layout_marginTop="268dp"

android:text="ADD"

app:layout_constraintEnd_toEndOf="parent"

app:layout_constraintHorizontal_bias="0.491"

app:layout_constraintStart_toStartOf="parent"

app:layout_constraintTop_toTopOf="parent"

app:toggleCheckedStateOnClick="false" />

<TextView

android:id="@+id/textView2"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_marginTop="368dp"

android:text="Sum :"

android:textSize="34sp"

app:layout_constraintEnd_toEndOf="parent"

app:layout_constraintHorizontal_bias="0.199"

app:layout_constraintStart_toStartOf="parent"

app:layout_constraintTop_toTopOf="parent" />

<EditText

android:id="@+id/editTextNumber"

android:layout_width="296dp"

android:layout_height="62dp"

android:layout_marginTop="108dp"

android:ems="10"

android:inputType="number"

app:layout_constraintEnd_toEndOf="parent"

app:layout_constraintHorizontal_bias="0.495"

app:layout_constraintStart_toStartOf="parent"

app:layout_constraintTop_toTopOf="parent" />

<EditText

android:id="@+id/editTextNumber2"

android:layout_width="295dp"

android:layout_height="58dp"

android:layout_marginTop="196dp"

android:ems="10"

android:inputType="number"

app:layout_constraintEnd_toEndOf="parent"

app:layout_constraintHorizontal_bias="0.491"

app:layout_constraintStart_toStartOf="parent"

app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity.java

package com.ebhor.addition;

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;
import android.widget.Toast;


public class MainActivity extends AppCompatActivity {
    EditText number1;
    EditText number2;
    TextView result;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        number1 = (EditText) findViewById(R.id.editTextNumber);
        number2 = (EditText) findViewById(R.id.editTextNumber2);
        result = (TextView) findViewById(R.id.textView2);
        Button add = (Button) findViewById(R.id.button);
        add.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {

                int num1 = Integer.parseInt(number1.getText().toString());
                int num2 = Integer.parseInt(number2.getText().toString());
                int sum = num1 + num2;
                result.setText("Sum :" + sum);
                Toast.makeText(MainActivity.this, "Sum :"+sum, Toast.LENGTH_SHORT).show();
            }
        });
    }

}

package com.ebhor.addition;

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;

import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

EditText number1;

EditText number2;

TextView result;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

number1 = (EditText) findViewById(R.id.editTextNumber);

number2 = (EditText) findViewById(R.id.editTextNumber2);

result = (TextView) findViewById(R.id.textView2);

Button add = (Button) findViewById(R.id.button);

add.setOnClickListener(new View.OnClickListener() {

public void onClick(View v) {

int num1 = Integer.parseInt(number1.getText().toString());

int num2 = Integer.parseInt(number2.getText().toString());

int sum = num1 + num2;

result.setText("Sum :" + sum);

Toast.makeText(MainActivity.this, "Sum :"+sum, Toast.LENGTH_SHORT).show();

}

});

}

It defines an Android activity called MainActivity.
In the onCreate method, it sets the content view to the layout defined in R.layout.activity_main.
It initializes three UI elements:
- number1: An EditText widget for entering the first number.
- number2: An EditText widget for entering the second number.
- result: A TextView widget for displaying the result of the addition.
It initializes a Button called add and sets an OnClickListener for it.
When the “add” button is clicked, it does the following:
- It retrieves the values entered in number1 and number2 EditText widgets as strings.
- It converts these string values to integers using Integer.parseInt().
- It calculates the sum of num1 and num2.
- It sets the TextView (result) to display the calculated sum.
- It also displays a toast message with the sum as a notification.

To validate we will use the Saripaar library.

Add this library to the build.gradle in the dependencies section as below

To use Saripaar in the program

Implement the Interface Validator.ValidationListener
Override two methods public void onValidationSucceeded() and public void onValidationFailed(List errors)

Overridden implementation is given below.

package com.ebhor.addition;

import androidx.appcompat.app.AppCompatActivity;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import com.mobsandgeeks.saripaar.ValidationError;
import com.mobsandgeeks.saripaar.Validator;
import com.mobsandgeeks.saripaar.annotation.NotEmpty;

import java.util.List;


public class MainActivity extends Activity implements Validator.ValidationListener {
    @NotEmpty(message = "Please Enter number1")
    EditText number1;
    @NotEmpty(message = "Please Enter number2")
    EditText number2;
    TextView result;
    Validator validator;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        number1 = (EditText) findViewById(R.id.editTextNumber);
        number2 = (EditText) findViewById(R.id.editTextNumber2);
        result = (TextView) findViewById(R.id.textView2);
        Button add = (Button) findViewById(R.id.button);
        validator = new Validator(this);
        validator.setValidationListener(this);

        add.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                validator.validate();
            }
        });
    }

    public void addNumbers() {
        int num1 = Integer.parseInt(number1.getText().toString());
        int num2 = Integer.parseInt(number2.getText().toString());
        int sum = num1 + num2;
        result.setText("Sum :" + sum);
        Toast.makeText(MainActivity.this, "Sum :" + sum, Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onValidationSucceeded() {
        addNumbers();
    }

    @Override
    public void onValidationFailed(List<ValidationError> errors) {
        for (ValidationError error : errors) {
            View view = error.getView();
            String message = error.getCollatedErrorMessage(this);

            // Display error messages ;)
            if (view instanceof EditText) {
                ((EditText) view).setError(message);
            } else {
                Toast.makeText(this, message, Toast.LENGTH_LONG).show();
            }
        }
    }

}

package com.ebhor.addition;

import androidx.appcompat.app.AppCompatActivity;

import android.app.Activity;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.EditText;

import android.widget.TextView;

import android.widget.Toast;

import com.mobsandgeeks.saripaar.ValidationError;

import com.mobsandgeeks.saripaar.Validator;

import com.mobsandgeeks.saripaar.annotation.NotEmpty;

import java.util.List;

public class MainActivity extends Activity implements Validator.ValidationListener {

@NotEmpty(message = "Please Enter number1")

EditText number1;

@NotEmpty(message = "Please Enter number2")

EditText number2;

TextView result;

Validator validator;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

number1 = (EditText) findViewById(R.id.editTextNumber);

number2 = (EditText) findViewById(R.id.editTextNumber2);

result = (TextView) findViewById(R.id.textView2);

Button add = (Button) findViewById(R.id.button);

validator = new Validator(this);

validator.setValidationListener(this);

add.setOnClickListener(new View.OnClickListener() {

public void onClick(View v) {

validator.validate();

}

});

}

public void addNumbers() {

int num1 = Integer.parseInt(number1.getText().toString());

int num2 = Integer.parseInt(number2.getText().toString());

int sum = num1 + num2;

result.setText("Sum :" + sum);

Toast.makeText(MainActivity.this, "Sum :" + sum, Toast.LENGTH_SHORT).show();

}

@Override

public void onValidationSucceeded() {

addNumbers();

}

@Override

public void onValidationFailed(List<ValidationError> errors) {

for (ValidationError error : errors) {

View view = error.getView();

String message = error.getCollatedErrorMessage(this);

// Display error messages ;)

if (view instanceof EditText) {

((EditText) view).setError(message);

} else {

Toast.makeText(this, message, Toast.LENGTH_LONG).show();

}

Hope you learn Addition of two numbers in Android.

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MainActivity.java

To validate we will use the Saripaar library.

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