How to find Prime number between two numbers

What is prime number:

A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. In other words, a prime number is a whole number greater than 1 that cannot be formed by multiplying two smaller natural numbers. For example, 2, 3, 5, 7, 11, and 13 are prime numbers because they cannot be divided evenly by any other number except 1 and themselves. However, 4 is not a prime number because it can be divided evenly by 1, 2, and 4

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<layout>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <EditText
        android:id="@+id/editText1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter starting number"
        android:inputType="number"
        android:layout_margin="16dp"/>

    <EditText
        android:id="@+id/editText2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter ending number"
        android:inputType="number"
        android:layout_below="@id/editText1"
        android:layout_margin="16dp"/>

    <Button
        android:id="@+id/calculateButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/editText2"
        android:layout_centerHorizontal="true"
        android:text="Calculate"/>

    <TextView
        android:id="@+id/resultTextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/calculateButton"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="16dp"/>
</RelativeLayout>
</layout>

MainActivity.kt

package com.androindian.primenumber

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.databinding.DataBindingUtil
import com.androindian.primenumber.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {
    var biniding:ActivityMainBinding?=null
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        biniding=DataBindingUtil.setContentView(this, R.layout.activity_main)

        biniding?.calculateButton?.setOnClickListener {
                    val start = biniding?.editText1?.text.toString().toIntOrNull() ?: 0
                    val end = biniding?.editText2?.text.toString().toIntOrNull() ?: 0

            biniding?.resultTextView?.text = findPrimes(start, end)
                }
            }

            private fun isPrime(n: Int): Boolean {
                if (n <= 1) return false
                if (n <= 3) return true
                if (n % 2 == 0 || n % 3 == 0) return false
                var i = 5
                while (i * i <= n) {
                    if (n % i == 0 || n % (i + 2) == 0) return false
                    i += 6
                }
                return true
            }

            private fun findPrimes(start: Int, end: Int): String {
                val primes = StringBuilder()
                for (i in start..end) {
                    if (isPrime(i)) {
                        primes.append("$i ")
                    }
                }
                return if (primes.isEmpty()) {
                    "No prime numbers found between $start and $end"
                } else {
                    "Prime numbers between $start and $end: ${primes.toString().trim()}"
                }
            }
        }

build.gradle

plugins {
    id("com.android.application")
    id("org.jetbrains.kotlin.android")
}

android {
    namespace = "com.androindian.primenumber"
    compileSdk = 34

    defaultConfig {
        applicationId = "com.androindian.primenumber"
        minSdk = 24
        targetSdk = 34
        versionCode = 1
        versionName = "1.0"

        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            isMinifyEnabled = false
            proguardFiles(
                getDefaultProguardFile("proguard-android-optimize.txt"),
                "proguard-rules.pro"
            )
        }
    }
    compileOptions {
        sourceCompatibility = JavaVersion.VERSION_1_8
        targetCompatibility = JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = "1.8"
    }
    dataBinding{
        enable=true
    }
}

dependencies {

    implementation("androidx.core:core-ktx:1.13.1")
    implementation("androidx.appcompat:appcompat:1.6.1")
    implementation("com.google.android.material:material:1.12.0")
    implementation("androidx.constraintlayout:constraintlayout:2.1.4")
    testImplementation("junit:junit:4.13.2")
    androidTestImplementation("androidx.test.ext:junit:1.1.5")
    androidTestImplementation("androidx.test.espresso:espresso-core:3.5.1")
}