[Kotlin] MultiValueMap to Map, Map to MultiValueMap, Object to MultiValueMap

MultiValueMap to Map

@Test
fun multiValueMapToMap() {

    val multiValueMap = LinkedMultiValueMap<String, String>()

    multiValueMap["a"] = "a"
    multiValueMap["b"] = "b"
    multiValueMap["c"] = "c"

    val map = multiValueMap.entries.associate { it.key to it.value[0] }

    println(map) // {a=a, b=b, c=c}
}

 

Map to MultiValueMap

@Test
fun mapToMultiValueMap() {

    val map = HashMap<String, String>()

    map["a"] = "a"
    map["b"] = "b"
    map["c"] = "c"

    val multiValueMap = LinkedMultiValueMap<String, String>().apply { setAll(map) }

    println(multiValueMap) // {a=[a], b=[b], c=[c]}
}

 

Object to MultiValueMap

class Student(
    val id: Long,
    val name: String
)

@Test
fun objectToMultiValueMap() {

    val student = Student(1, "effortguy")

    val multiValueMap = jacksonObjectMapper()
        .convertValue<Map<String, String>>(student)
        .let { LinkedMultiValueMap<String, String>().apply { setAll(it) } }

    println(multiValueMap) // {id=[1], name=[effortguy]}
}