예외 종류
- 일반 예외 : 반드시 처리를 해야하는 항목
- kotlin 지원 X
- 즉 반드시 예외 처리를 할 필요 X
- 실행 예외(RuntimeException) 중심
- throw IOException
구문
try ... catch ... catch ... [finally]- 복수 catch 처리 가능
fun main() {
try {
10/0
} catch (e: ArithmeticException) {
println(e.message)
} finally {
println("finally block")
}
println("ㅇㅇ")
}
>>>
App.kt:10:9: warning: division by zero.
10/0
^^^^
/ by zero
finally block
ㅇㅇ
throw exceptionClass(message)
fun divide(a: Int, b: Int): Int {
if (b==0) {
throw IllegalArgumentException("0으로 못나눔")
}
return a / b
}
fun executeDivide(a: Int, b: Int) {
try {
println(divide(a, b))
} catch (e: IllegalArgumentException) {
println(e.message)
}
}
fun main() {
executeDivide(10, 0) // 0으로 못나눔
executeDivide(10, 3) // 3
}
- sealed class 이용 : 실패를 하나의 상태로 사용
sealed class Result
data class Success(val result: Int): Result()
data class Failure(val errorMessage: String): Result()
fun safeDivide(a: Int, b: Int): Result {
return if (b==0) {
Failure("0 나누기")
} else {
Success(a / b)
}
}
fun main() {
val result = safeDivide(10, 0)
when (result) {
is Success -> println("result : $result.result")
is Failure -> println(result.errorMessage)
}
}
예제
fun parseInt(str: String): Int? = str.toInt()
fun main() {
try {
println(parseInt("1235a21b34"))
} catch (e: NumberFormatException) {
println(e.message) // For input string: "1235a21b34"
}
}
fun main() {
val index = arrayOf(1,2,3)
try {
index[4]
} catch (e: IndexOutOfBoundsException) {
println(e.message) // Index 4 out of bounds for length 3
}
}
class InvalidAgeException(message: String = "invalid age"): Exception(message)
fun main() {
val age = 50
if (age < 0 || age > 150) {
throw InvalidAgeException()
} else {
println(age)
}
}
>>>
Exception in thread "main" org.example.app.InvalidAgeException: invalid age
at org.example.app.AppKt.main(App.kt:12)
at org.example.app.AppKt.main(App.kt)
fun main() {
val array = arrayOf(0, 1, 2)
val index = "3" // Index 3 out of bounds for length 3
val index = "a" // 숫자를 입력하셈 java.lang.NumberFormatException: For input string: "a".message
try {
array[index.toInt()]
} catch (e: NumberFormatException){
println("숫자를 입력하셈 $e.message")
} catch (e: IndexOutOfBoundsException) {
println(e.message)
}
}
sealed class DividResult
data class Success(val result: Int): DividResult()
data class Failure(val errorMessage: String): DividResult()
fun safeDivide(a: Int, b: Int): DividResult {
if (b==0){
return Failure("divided by 0")
} else {
return Success(a / b)
}
}
fun main() {
val result1 = safeDivide(100, 0)
val result2 = safeDivide(100, 17)
val printDivide = { result: DividResult ->
when(result) {
is Success -> result.result
is Failure -> result.errorMessage
}
}
println(printDivide(result1)) // divided by 0
println(printDivide(result2)) // 5
}
C
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