Hello dear friends today we are learn about what difference in run, with, let, also and apply . This is master function of the kotlin.
Example 1:
var student= Student("samset",100)
var result = student.let{ it.rollno=50}
Log.e(" student roll no : "+student)
Log.e("result student roll no : "+result)
OUTPUT:
100
50
here it keyword copy of the property inside the let. let function scope only inside the expression cannot be used outside of the expression.
Example 2:
var strlength = str.let { "$it my function".length}
println("strlength is $strlength") // strlength is 30
class MyTestClass{
fun testfunction(){
val str : String = "welcome to kotlin"
val myresult = str.let{
print(this) // this is instance of MyTestClass
print(it) // it is the String = "welcome to kotlin" on which we have called let
}
}
}
Chaining let functon:
val strmain="welcome"
// Evolve the value and send to the next chain
strmain.let{
println("This is main original string $it") // "welcome"
it.reversed() // evolve it as parameter to send to next let
}.let{
println("This is reverse string $it") // "emoclew"
it.length // evolve it as parameter to next let
}.let{
println("The length of string is $it") // 7
}
Outer let:
After nested let used now we are use outer let:
var str="Smaset"
str = str.let{ outer->
outer.let{ inner->
println(" Inner let is "$inner)
}
"Outerlet is $outer"
}
println(str)
OUTPUT:
Inner let is samset
Outer let is samset
let check Null:
var strmain = String? = "welcome"
strmain ?.let{ println(it)} // prints welcome
strmain =null
strmain ?.let{ println(it)} // nothing happens
println(str) // This is a run function
OUTPUT:
Hello welcome to kotlin
This is a run function
var mytext : String? = null
p?.let{ println(" Text is $mytext ")} ?:
run { println("Text was null so set default value :"+ mytext ="Default text")}
println(mytext)
OUTPUT:
Text was null so set default value : Default text
Kotlin let vs also
also is something same like let but this is return only original value. Rhe also expression return the data class object whereas th let expression return nothing (Unit) as we didn't specify anything explicitly see example for understanding...
data class Student(var name: String,var rollno : int)
var stud = Student("Samset",101)
var s = stud.let{ it.name = "sanjoo"}
var salso = stud.also{ it.name = "sanjoo"}
println(s)
println(salso)
println(stud)
OUTPUT:
sanjoo
sanjoo
Kotlin let:
let take the object is invoked upon as the parameter and return the result of the lambda expression. In other word we also said let is a non-nomadic version of map. It is accept the object as a parameters and returns the result of the lambda. like...Example 1:
var student= Student("samset",100)
var result = student.let{ it.rollno=50}
Log.e(" student roll no : "+student)
Log.e("result student roll no : "+result)
OUTPUT:
100
50
here it keyword copy of the property inside the let. let function scope only inside the expression cannot be used outside of the expression.
Example 2:
var strlength = str.let { "$it my function".length}
println("strlength is $strlength") // strlength is 30
class MyTestClass{
fun testfunction(){
val str : String = "welcome to kotlin"
val myresult = str.let{
print(this) // this is instance of MyTestClass
print(it) // it is the String = "welcome to kotlin" on which we have called let
}
}
}
Chaining let functon:
val strmain="welcome"
// Evolve the value and send to the next chain
strmain.let{
println("This is main original string $it") // "welcome"
it.reversed() // evolve it as parameter to send to next let
}.let{
println("This is reverse string $it") // "emoclew"
it.length // evolve it as parameter to next let
}.let{
println("The length of string is $it") // 7
}
Outer let:
After nested let used now we are use outer let:
var str="Smaset"
str = str.let{ outer->
outer.let{ inner->
println(" Inner let is "$inner)
}
"Outerlet is $outer"
}
println(str)
OUTPUT:
Inner let is samset
Outer let is samset
let check Null:
var strmain = String? = "welcome"
strmain ?.let{ println(it)} // prints welcome
strmain =null
strmain ?.let{ println(it)} // nothing happens
Kotlin run:
Kotlin run is another interesting function. The following example demonstrates its use cases. run does not return values and does not support it keyword.
var str = "Hello welcome to kotlin"
println(str) // "Hello welcome to kotlin"
val str = "This is a run function" str
}println(str) // This is a run function
OUTPUT:
Hello welcome to kotlin
This is a run function
let with run
var mytext : String? = null
p?.let{ println(" Text is $mytext ")} ?:
run { println("Text was null so set default value :"+ mytext ="Default text")}
println(mytext)
OUTPUT:
Text was null so set default value : Default text
Kotlin let vs also
also is something same like let but this is return only original value. Rhe also expression return the data class object whereas th let expression return nothing (Unit) as we didn't specify anything explicitly see example for understanding...
data class Student(var name: String,var rollno : int)
var stud = Student("Samset",101)
var s = stud.let{ it.name = "sanjoo"}
var salso = stud.also{ it.name = "sanjoo"}
println(s)
println(salso)
println(stud)
OUTPUT:
sanjoo
sanjoo
