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
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 | <?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
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 | 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(); } }); } } |
Adding validation in
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()andpublic void onValidationFailed(List errors)
Overridden implementation is given below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 | 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(); } } } } |