Convert hex string to integer in Kotlin

This article explores different ways to convert a hex string to an integer in Kotlin.

1. Using `toInt()` function

The Integer class contains several functions to convert the hex string (up to 0x7FFFFFFF) to an integer:

1. The Integer.decode() function takes a hexadecimal string preceded with the radix specifier (0x/0X) and decodes it into an integer.

fun main() {

val hex = "0x7FFFFFFF" // with radix specifier

val decimal = Integer.decode(hex)

println(decimal) // 2147483647

}

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2. The String.toInt() function parse a string as an integer in the specified radix.

fun main() {

val hex = "7FFFFFFF"

val decimal: Int = hex.toInt(16)

println(decimal) // 2147483647

}

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3. The Integer.valueOf() function parse a string as a signed integer in the specified radix.

fun main() {

val hex = "7FFFFFFF"

val decimal = Integer.valueOf(hex, 16)

println(decimal) // 2147483647

}

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2. Using `toLong()` function

All the above functions cannot parse a hexadecimal value greater than 0x7FFFFFFF (Int.MAX_VALUE in numeric). To handle large hexadecimal values up to 0x7FFFFFFFFFFFFFFF (Long.MAX_VALUE in numeric), use Long.decode() function instead.

fun main() {

val hex = "0x7FFFFFFFFFFFFFF" // with radix specifier

val decimal = java.lang.Long.decode(hex)

println(decimal) // 576460752303423487

}

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Alternately, use the String.toLong() function to parse a string as a long in the specified radix.

fun main() {

val hex = "7FFFFFFFFFFFFFF"

val decimal = hex.toLong(16)

println(decimal) // 576460752303423487

}

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3. Using `BigInteger` class

To handle even larger numbers than 0x7FFFFFFFFFFFFFFF, consider using BigInteger, whose constructor translates the hexadecimal string into a BigInteger in the given radix.

import java.math.BigInteger

fun main() {

val hex = "7FFFFFFFFFFFFFFFFFFFFF"

val decimal = BigInteger(hex, 16)

println(decimal) // 154742504910672534362390527

}

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That’s all about converting a hex string to an integer in Kotlin.

Convert hex string to integer in Kotlin

1. Using toInt() function

2. Using toLong() function

3. Using BigInteger class

1. Using `toInt()` function

2. Using `toLong()` function

3. Using `BigInteger` class