Build an Android App to Check a Number is Armstrong or Not
What is Armstrong’s number? A number is said to be Armstrong if the sum of its digits is raised to the power of the total number of digits in the number. Given a number x, determine whether the given number is Armstrong’s number or not. A positive integer of n digits is called an Armstrong number of order n (order is the number of digits) if.
abcd... = pow(a,n) + pow(b,n) + pow(c,n) + pow(d,n) + ....
Example:
153 is an Armstrong number. 1*1*1 + 5*5*5 + 3*3*3 = 153 120 is not an Armstrong number. 1*1*1 + 2*2*2 + 0*0*0 = 9 1253 is not an Armstrong Number 1*1*1*1 + 2*2*2*2 + 5*5*5*5 + 3*3*3*3 = 723 1634 is an Armstrong Number 1*1*1*1 + 6*6*6*6 + 3*3*3*3 + 4*4*4*4 = 1634
Step by Step Implementation
Step 1: Create a New Project
To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. Note that select Java as the programming language.
Step 2: Working with the activity_main.xml file
Navigate to the app > res > layout > activity_main.xml and add the below code to that file. Below is the code for the activity_main.xml file.
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" android:background = "@color/teal_200" > < TextView android:layout_width = "wrap_content" android:layout_height = "wrap_content" android:text = "Armstrong Number or Not" android:textColor = "@color/black" android:textSize = "26sp" app:layout_constraintBottom_toTopOf = "@+id/textView" app:layout_constraintEnd_toEndOf = "parent" app:layout_constraintStart_toStartOf = "parent" app:layout_constraintTop_toTopOf = "parent" app:layout_constraintVertical_bias = "0.491" /> < TextView android:id = "@+id/textView" android:layout_width = "wrap_content" android:layout_height = "wrap_content" android:text = "Enter a number to check Armstrong Number" android:textColor = "@color/black" android:textSize = "18sp" app:layout_constraintBottom_toBottomOf = "parent" app:layout_constraintHorizontal_bias = "0.494" app:layout_constraintLeft_toLeftOf = "parent" app:layout_constraintRight_toRightOf = "parent" app:layout_constraintTop_toTopOf = "parent" app:layout_constraintVertical_bias = "0.4" /> < EditText android:id = "@+id/etNum" android:layout_width = "match_parent" android:layout_height = "wrap_content" android:layout_margin = "10dp" android:hint = "ENTER THE NUMBER" android:inputType = "number" app:layout_constraintEnd_toEndOf = "@+id/textView" app:layout_constraintStart_toStartOf = "@+id/textView" app:layout_constraintTop_toBottomOf = "@+id/textView" /> < Button android:id = "@+id/btnCheck" android:layout_width = "149dp" android:layout_height = "50dp" android:layout_margin = "10dp" android:layout_marginTop = "16dp" android:backgroundTint = "@color/black" android:text = "Check" android:textColor = "@color/teal_700" app:layout_constraintBottom_toBottomOf = "parent" app:layout_constraintEnd_toEndOf = "@+id/etNum" app:layout_constraintHorizontal_bias = "0.496" app:layout_constraintStart_toStartOf = "@+id/etNum" app:layout_constraintTop_toBottomOf = "@+id/etNum" app:layout_constraintVertical_bias = "0.113" /> </ androidx.constraintlayout.widget.ConstraintLayout > |
Step 3: Working with the MainActivity.kt file
Go to the MainActivity.kt file and refer to the following code. Below is the code for the MainActivity.kt file. Comments are added inside the code to understand the code in more detail. Here we will bind the views and write the logic of the app.
Kotlin
import androidx.appcompat.app.AppCompatActivity import android.os.Bundle import android.widget.Button import android.widget.EditText import android.widget.Toast import java.lang.Math.pow import kotlin.math.pow class MainActivity : AppCompatActivity() { lateinit var btnCheck : Button lateinit var etNum : EditText override fun onCreate(savedInstanceState: Bundle?) { super .onCreate(savedInstanceState) setContentView(R.layout.activity_main) supportActionBar?.hide() // Binding the views btnCheck = findViewById(R.id.btnCheck) etNum = findViewById(R.id.etNum) btnCheck.setOnClickListener { val n = etNum.text.toString().length val num = etNum.text.toString().toInt() var temp = num var result = 0 while (temp != 0 ){ val remainder = temp % 10 result += (remainder.toDouble().pow(n.toDouble())).toInt() temp /= 10 } if (result == num) Toast.makeText( this , "Armstrong Number" ,Toast.LENGTH_SHORT).show() else Toast.makeText( this , "Not an Armstrong Number" ,Toast.LENGTH_SHORT).show() } } } |
Output: