ch8n

// Kotlin signature
typealias LinkedHashMap<K, V> = LinkedHashMap<K, V>
// Java signature
class LinkedHashMap<K,V>
  extends HashMap<K,V>
  implements Map<K,V>
// Available Constructors
Java LinkedHashMap has three constructors
 - LinkedHashMap() 
 - LinkedHashMap(int initialCapacity)

ch8n

// Directly use the 4th constructor example
 val contact = mapOf("chetan" to "[email protected]")
 val hashMapOfContact = HashMap(contact)
//Or create and add all entries
 val hashMapOfContact = HashMap<String,Int>()
 hashMapOfContact.putAll(contact)

ch8n

val hashMap = HashMap<String,Int>()

ch8n

fun <K, V> hashMapOf(vararg pairs: Pair<K, V>): HashMap<K, V> 
      = HashMap<K, V>(mapCapacity(pairs.size)).apply { putAll(pairs) }
// this factory function takes pair and uses HashMap's second constructor which
// start off with the object capacity as the number of pairs passed

ch8n

fun <K, V> hashMapOf(): HashMap<K, V> = HashMap<K, V>()
// hashmapOf directly create HashMap object default constructor
// Java HashMap default constructor create HashMap with 
// * inital capacity 16 and * LoadFactor 0.75

ch8n

// Kotlin Standard Library function
fun <K, V> hashMapOf(): HashMap<K, V>
fun <K, V> hashMapOf(vararg pairs: Pair<K, V>): HashMap<K, V>

ch8n

// Kotlin signature
typealias HashMap<K, V> = HashMap<K, V>
// Java signature
class HashMap<K,V> 
  extends AbstractMap<K,V> 
  implements Map<K,V>, Cloneable, Serializable
// AbstractMap<K,V> is a skeletal implementation of the Map interface,
// Java's Map<K,V> is very close to MutableMap<K,V> than kotlin's Map<K,V>
// i.e it contains mutable opertaions internally, though use structures named 
// similar to Kotlin's Map<K,V> like Map.Entry but are infact Mutable Entry

ch8n

fun <K, V> mutableMapOf(vararg pairs: Pair<K, V>): MutableMap<K, V> 
  = LinkedHashMap<K, V>(mapCapacity(pairs.size))
    .apply { putAll(pairs) }
// resolved with LinkedHashMap only

ch8n

fun <K, V> mutableMapOf(): MutableMap<K, V> = LinkedHashMap()
// mutableMapOf is resolved using LinkedHashMap
// as discussed earlier Linked HashMap signature
class LinkedHashMap<K, V> : MutableMap<K, V>

ch8n

// Kotlin Standard Library function
fun <K, V> mutableMapOf(): MutableMap<K, V>
fun <K, V> mutableMapOf(vararg pairs: Pair<K, V> ): MutableMap<K, V>