KOTLIN - ziua 2

Fisier kt -> .class file

Rulare:

> java -cp ...\kotlin-runtime.jar MainKt 

Alta optiune: export jar

> java -jar MainKt.jar

Mai putina "ceremonie":

- poti defini clase oriunde, nu trebuie sa fie in fisier separat

STRINGS

- string interpolation: 

  println("Display $name")

  println("Display $(obj.name)")

- string comparison: if (str1 == str2)

- nullable vs non-nullable

  var answer: String; // non-nullable

  var answer: String?; // nullable

- string comparison with null check: if (str1?.prop == str2?.prop) // compara doar daca nu sunt nule

IF este o expresie care returneaza o valoare:

var message = if (str1 == str2) { "egal" } else { "gresit" } 

WHEN - asemanator cu switch

 when (str1) {

  "25" -> print("Corect")

  else -> print("Gresit")

}

TRY - CATCH

val num: Int = try {
    Integer.parseInt("20s")
} catch (e: NumberFormatException) {
    -1
} finally {

}

Iteratii - WHILE, FOR

var range = 1..10 // inclusive

// poate fi si range = 'a'..'z' --- orice care implementeaza interfata Comparable

for (i in range step 3) {
    println(i)
}
for (i in 10 downTo 1 step 4) {
    println(i)
}
for (i in 1 until 10) { // non-inclusive
    println(i)
}

LISTE

var nums = listOf(11,22,33)
for (i in nums) {
    println(i)
}

for ((index, element) in nums.withIndex()) {
    println("$element at index $index")
}

MAPS

var ages = TreeMap<String, Int>()
ages["Geo"] = 33
ages["Petri"] = 7
for ((name, age) in ages) {
    println("$name's age is $age")
}