import android.Manifest
import android.app.KeyguardManager
import android.content.Context
import android.content.pm.PackageManager
import android.hardware.fingerprint.FingerprintManager
import android.os.Build
import androidx.core.app.ActivityCompat
import androidx.core.content.ContextCompat

fun authenticateFingerprint(context: Context) {
    // Check if the device is running Marshmallow or above
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        val fingerprintManager = context.getSystemService(FingerprintManager::class.java)
        val keyguardManager = context.getSystemService(KeyguardManager::class.java)

        // Check if the device has a fingerprint sensor
        if (!fingerprintManager.isHardwareDetected) {
            // Show an error message if the device doesn't have a fingerprint sensor
            // ...
        } else {
            // Check if the user has granted permission to use fingerprint authentication
            if (ContextCompat.checkSelfPermission(context, Manifest.permission.USE_FINGERPRINT) != PackageManager.PERMISSION_GRANTED) {
                // Show a dialog to request the user's permission
                // ...
            } else {
                // Check if the user has set up a lock screen with a password
                if (!keyguardManager.isKeyguardSecure) {
                    // Show an error message if the user hasn't set up a lock screen
                    // ...
                } else {
                    // Authenticate the user's fingerprint
                    fingerprintManager.authenticate(null, null, 0, object : FingerprintManager.AuthenticationCallback() {
                        override fun onAuthenticationError(errorCode: Int, errString: CharSequence) {
                            super.onAuthenticationError(errorCode, errString)
                            // Show an error message if there was an error during authentication
                            // ...
                        }

                        override fun onAuthenticationSucceeded(result: FingerprintManager.AuthenticationResult) {
                            super.onAuthenticationSucceeded(result)
                            // Show a success message if the user's fingerprint was successfully authenticated
                            // ...
                        }

                        override fun onAuthenticationFailed() {
                            super.onAuthenticationFailed()
                            // Show a failure message if the user's fingerprint was not successfully authenticated
                            // ...
                        }
                    }, null)
                }
            }
        }
    }
}

Kotlin online compiler

Write, Run & Share Kotlin code online using OneCompiler’s Kotlin online compiler for free. It’s a modern and fast online playground for Kotlin, supporting the latest version and ideal for learning, experimenting, and sharing code instantly.

About Kotlin

Kotlin is a statically typed, modern programming language developed by JetBrains. It runs on the JVM and is fully interoperable with Java. Kotlin is concise, expressive, and safe, and it’s officially supported by Google for Android app development.

Sample Code

The following is a simple Kotlin program that prints a greeting:

fun main() {
    println("Hello, OneCompiler!")
}

Taking inputs (stdin)

OneCompiler’s Kotlin editor supports stdin. You can provide input using the I/O tab. Here's a sample program that reads a line of input and prints a greeting:

fun main() {
    print("Enter your name: ")
    val name = readLine()
    println("Hello, $name")
}

Syntax Basics

Variables

val name: String = "OneCompiler"  // Immutable
var age: Int = 25                 // Mutable

Kotlin supports type inference, so explicit types are optional:

val city = "Hyderabad"
var count = 10

Conditionals

val score = 85
if (score >= 50) {
    println("Pass")
} else {
    println("Fail")
}

Loops

For loop

for (i in 1..5) {
    println(i)
}

While loop

var i = 1
while (i <= 5) {
    println(i)
    i++
}

Do-While loop

var j = 1
do {
    println(j)
    j++
} while (j <= 5)

Functions

fun add(a: Int, b: Int): Int {
    return a + b
}

fun greet(name: String) = "Hello, $name"

Collections

val items = listOf("apple", "banana", "cherry")
for (item in items) {
    println(item)
}

This guide provides a quick reference to Kotlin programming syntax and features. Start coding in Kotlin using OneCompiler’s Kotlin online compiler today!