package com.example.espl.hashmaptolistkotlin
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import java.security.KeyPair
class
MainActivity : AppCompatActivity() {
// fun <K, V> hashMapOf(): HashMap<K, V>
// Returns an empty new HashMap.
//Method hashMapOf() in Kotlin
val hashMap: HashMap<Int,String> =
hashMapOf()
override fun
onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
hashMap.put(1,"Value1")
hashMap.put(2,"Value2")
hashMap.put(3,"Value3")
hashMap.put(4,"Value4")
hashMap.put(5,"Value5")
//print hash map in Log
Log.e("hashmap","::"+hashMap)
// Returns a [List] containing all key-value pairs.
// public fun <K, V> Map<out K, V>.toList(): List<Pair<K, V>>
// Convert Kotlin Map to List using toList() method
val pairKeyValueList :
List<Pair<Int, String>> =
hashMap.toList();
Log.e("HashmapPairKeyValueList","::"+pairKeyValueList)
// Convert Kotlin Map to List of keys after extracting the keys
//public Set<K> keySet() method return a set view of the keys contained in this map
val listKeys : Set<Int> =
hashMap.keys
//Convert the returned set to ArrayList
val
arraListOfKeys: List<Int> = ArrayList<Int>(
listKeys.toList())
Log.e("hashmap:arraListOfKeys","::"+
arraListOfKeys)
// Convert Kotlin Map to List after extracting the values
//public Collection<V> values() method return a view of the values contained in this map
val listValues =
hashMap.values
//Convert the returned Collection to ArrayList
val
arraListOfvalues: List<String> = ArrayList<String>(
listValues.toList())
Log.e("hashmap:arraListOfvalues","::"+
arraListOfvalues)
val
students:HashMap<Int,Student> =
hashMapOf()
students.put(1, Student("Ram", "VI", Address("New street", "Ahmedabad")))
students.put(2, Student("Raju", "V", Address("Green cross", "Rajkot")))
val
pairKeyValueListStudents:ArrayList<Pair<Int,Student>> = ArrayList(
students.toList())
Log.e("HashmapPairKeyValueList","::"+
pairKeyValueListStudents)
val
listKeysStudents: Set<Int> = students.keys
Log.e("map:listKeysStudents","::"+
listKeysStudents)
//public Collection<V> values() method return a view of the values(student objects) contained in this map
val
listValuesStudents:ArrayList<Student> = ArrayList(students.values)
Log.e("listValuesStudents","::"+
listValuesStudents)
val
listValuesStudentsAddress:ArrayList<Address> = ArrayList(
students.values.map { x->x.address})
Log.e("listValStudentsAddress","::"+
listValuesStudentsAddress)
// While working with Map Object, we can associate with map(transform: (T) -> R) function to customise a returned-list
val
listValuesStudentsCity: List<String?> =
students.values.map { x->x.address.city}
Log.e("listValuesStudentsCity","::"+
listValuesStudentsCity)
}
data class
Address(
var street : String? = null,
var city : String? = null
){}
data class
Student(
var name: String? = null,
var std: String? = null,
var address: Address = Address()) {
}
}
com.example.espl.hashmaptolistkotlin E/
hashmap: ::
{4=Value4, 1=Value1, 5=Value5, 3=Value3, 2=Value2}
com.example.espl.hashmaptolistkotlin E/
HashmapPairKeyValueList: ::
[(4, Value4), (1, Value1), (5, Value5), (3, Value3), (2, Value2)]
com.example.espl.hashmaptolistkotlin E/
hashmap:arraListOfKeys: ::
[4, 1, 5, 3, 2]
com.example.espl.hashmaptolistkotlin E/
hashmap:arraListOfvalues: ::
[Value4, Value1, Value5, Value3, Value2]
com.example.espl.hashmaptolistkotlin E/
HashmapPairKeyValueList: ::
[(1, Student(name=Ram, std=VI, address=Address(street=New street, city=Ahmedabad))), (2, Student(name=Raju, std=V, address=Address(street=Green cross, city=Rajkot)))]
com.example.espl.hashmaptolistkotlin E/
map:listKeysStudents: ::
[1, 2]
com.example.espl.hashmaptolistkotlin E/
listValuesStudents: ::
[Student(name=Ram, std=VI, address=Address(street=New street, city=Ahmedabad)), Student(name=Raju, std=V, address=Address(street=Green cross, city=Rajkot))]
com.example.espl.hashmaptolistkotlin E/
listValStudentsAddress: ::
[Address(street=New street, city=Ahmedabad), Address(street=Green cross, city=Rajkot)]
com.example.espl.hashmaptolistkotlin E/
listValuesStudentsCity: ::
[Ahmedabad, Rajkot]
