import android.os.Bundle
import android.view.GestureDetector
import android.view.MotionEvent
import androidx.appcompat.app.AppCompatActivity
import kotlin.math.abs

class FlashcardActivity : AppCompatActivity() {

    private lateinit var questionTextView: TextView
    private lateinit var answerTextView: TextView

    private lateinit var gestureDetector: GestureDetector

    private var isAnswerVisible = false

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_flashcard)

        questionTextView = findViewById(R.id.questionTextView)
        answerTextView = findViewById(R.id.answerTextView)

        gestureDetector = GestureDetector(this, MyGestureListener())
    }

    override fun onTouchEvent(event: MotionEvent): Boolean {
        gestureDetector.onTouchEvent(event)
        return super.onTouchEvent(event)
    }

    inner class MyGestureListener : GestureDetector.SimpleOnGestureListener() {
        override fun onFling(
            e1: MotionEvent,
            e2: MotionEvent,
            velocityX: Float,
            velocityY: Float
        ): Boolean {
            val deltaX = e2.x - e1.x
            val deltaY = e2.y - e1.y

            if (abs(deltaX) > abs(deltaY)) {
                if (deltaX > 0) {
                    showNextQuestion()
                } else {
                    showAnswer()
                }
            } else {
                if (deltaY < 0) {
                    showAnswer()
                }
            }
            return true
        }
    }

    private fun showAnswer() {
        answerTextView.visibility = View.VISIBLE
        isAnswerVisible = true
    }

    private fun showNextQuestion() {
        // Code to show the next question
        // Reset visibility and other states
        answerTextView.visibility = View.GONE
        isAnswerVisible = false
    }
}

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!