How to cast String into Int and Long?

user_6236752 0
Viewed 7294

In Java we use 

Integer.valueOf(str)

and 

Long.valueOf(str)

to get the integer but how can we do the same in Kotlin?

kotlin-android-extensions kotlin
5 Answers

You can just use toInt, toLong, and similar conversion extensions.

For example:

val i: Int = str.toInt()
val l: Long = str.toLong()

There's also toIntOrNull, etc. in case your strings might not be valid numbers:

val i: Int? = str.toIntOrNull()
user_44652080

Kotlin has extension methods for String class that do the same but more elegantly.

str.toInt()
str.toLong()

Note that you can write extension methods yourself as well.

user_8984780

Kotlin define extension function in StringNumberConversions.kt like toInt, toLong etc. These functions internally invoke standard java function like java.lang.Integer.parseInt(...) or java.lang.Long.parseLong(...)

You can use them like :

"123".toInt()
"123".toLong()
user_17075200

These are Extension methods available for Strings to parse in KOTLIN:

    str.toBoolean()
    str.toInt()
    str.toLong()
    str.toFloat()
    str.toDouble()
    str.toByte()
    str.toShort()
user_63145130

it is better to 

val str = ""
val quotaInteger = str.toDouble().toInt()

cos sometime end give us like "123.22", if we use toInt(), it will throw out NumberFormatException

user_53193520
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