Boolean và Kiểu dữ liệu Boolean trong Kotlin

val isKotlinFun: Boolean = true
val isPythonBetter: Boolean = false
 
// Type inference
val isValid = true
val isEmpty = false

val age = 25
val isAdult = age >= 18        // true
val isTeenager = age in 13..19 // false
 
val score = 85
val isPassed = score >= 50     // true

val a = true
val b = false
 
// AND
println(a && b)   // false
 
// OR
println(a || b)   // true
 
// NOT
println(!a)       // false
println(!b)       // true

val value: Boolean? = null
 
// Safe call
if (value == true) {
    println("Value is true")
}
 
// Elvis operator
val result = value ?: false

val isValid = true
 
println(isValid.toString())    // "true"
println(isValid.not())        // false (same as !isValid)
 
// and, or, xor
println(true and false)   // false (same as &&)
println(true or false)    // true (same as ||)
println(true xor false)   // true (exclusive or)

fun validateEmail(email: String): Boolean {
    val hasAt = email.contains("@")
    val hasDot = email.contains(".")
    val isLongEnough = email.length >= 5
 
    return hasAt && hasDot && isLongEnough
}
 
fun validatePassword(password: String): Boolean {
    return password.length >= 8 &&
           password.any { it.isUpperCase() } &&
           password.any { it.isLowerCase() } &&
           password.any { it.isDigit() }
}

val isWeekend = true
val isHoliday = false
 
// If statement
if (isWeekend) {
    println("Day off!")
}
 
// When expression
val status = when {
    isWeekend -> "Weekend"
    isHoliday -> "Holiday"
    else -> "Working day"
}
 
// While loop
var running = true
while (running) {
    // ...
    if (someCondition) running = false
}

// && và || sử dụng short-circuit evaluation
fun expensiveCheck(): Boolean {
    println("Expensive check running")
    return true
}
 
val result1 = false && expensiveCheck()  // Không gọi expensiveCheck()
val result2 = true || expensiveCheck()   // Không gọi expensiveCheck()

data class User(
    val name: String,
    val isActive: Boolean = true,
    val isAdmin: Boolean = false,
    val isVerified: Boolean = false
)
 
val user = User("Alice", isAdmin = true)
 
if (user.isActive && user.isAdmin) {
    println("${user.name} is an active admin")
}