Skip to content

Random Everything

Faker provides its wrapper functions around java.util.Random (with some additional functionality that is not covered by java.util.Random) through Faker().random property.

Wrappers around java.util.Random

faker.random.nextBoolean()
faker.random.nextChar()
faker.random.nextDouble()
faker.random.nextFloat()
faker.random.nextInt()
faker.random.nextInt(bound = 100)
faker.random.nextInt(min = 100, max = 999)
faker.random.nextInt(intRange = (0..99))
faker.random.nextLetter(upper = false)

Random Enum Instance

enum class Foo {
    ONE,
    TWO,
    FORTY_TWO
}

faker.random.nextEnum<Foo>()
faker.random.nextEnum(enum = Foo::class.java)
faker.random.nextEnum(values = Foo.values())
faker.random.nextEnum(enum = Foo::class.java) { it != Foo.ONE }
faker.random.nextEnum<Foo>("ONE")

Random Strings

faker.random.randomString(
    length = 42,
    numericalChars = false
)

faker.random.randomString(
    length = 24,
    locale = Locale.forLanguageTag("nb-NO"),
    indexChars = true,
    auxiliaryChars = true,
    punctuationChars = true,
    numericalChars = true,
)

Random sub-lists and sub-sets

val list = List(100) { it }
faker.random.randomSublist(list, size = 10, shuffled = true)
faker.random.randomSublist(list, sizeRange = 6..42, shuffled = true)

val set = setOf(*List(100) { it }.toTypedArray())
faker.random.randomSubset(set, size = 10, shuffled = true)
faker.random.randomSubset(set, sizeRange = 66..99, shuffled = true)

Random element from a list/array

val list = listOf(1, 2, 3)
faker.random.randomValue(list)

Random UUID

faker.random.nextUUID()

Unique Random Values

Just like most data providers, Faker#random supports generation of unique values. See Generating Unique Values page for usage details.

Both "local" (data-generator level) and "global" (faker level) generation of unique values are supported for RandomProvider:

val ints = List(21) {
    faker.random.unique.nextInt(42)
}
assert(ints.distinct().size == 21)
// cleanup of unique values via enum key for nextInt function
faker.random.unique.clear(RandomProvider.Key.NEXT_INT)

faker.unique.configuration { enable(faker::random) }
val uniqueInts = List(21) {
    faker.random.nextInt(42)
}
assert(uniqueInts.distinct().size == 21)
// cleanup global unique values for Random provider
faker.unique.clear(faker::random)
// disable global unique values for Random provider
faker.unique.configuration { disable(faker::random) }
val ints = List(21) {
    faker.random.nextInt(42)
}
assert(ints.distinct().size < 21)