Kotlin - Strings

Kotlin Strings are sequence of charactes similar to java. In kotlin all Strings are objects of String class

Create a String

 val myStr= "Hello Kotlin String"

Read Characters of String

val myStr = "Hello Kotlin String"
val item = myStr[0]
print(item)
                            

We can read all characters from string like below

fun main(args:Array)
{
    val myStr="Hello"

     for(str in myStr)
         println(str)
}

                            

Output: H e l l o

 Strings are immutable, that means we cannot modify a String by changing some of its elements
 var myString="Kotlin, New Version"  

 var myString:String="Kotlin, New Version"
println(myString.hashCode())

var myString2:String="Kotlin, New Version"
println(myString2.hashCode())


var my:StringBuffer = StringBuffer("k");
println(my.hashCode())

var my2:StringBuffer = StringBuffer("k");
println(my2.hashCode())

                        

Output:
780002467
780002467
1360875712
1625635731

-String pool is a special storage area in The Heap Memory. -When a string created and if string already exists in the pool, the reference address of the existing string will be returned, instead of creating a new object and returning its reference. -If string is mutable, changing the string with one reference will give wrong value for other references.

String Properties & Functions

length : This will returns the number charactes contians the String

get(index) : It will returns the character at given index inside the string

subSequence(startindex,endIndex) : This will retunrs the sub string of given string, startIndex is the start position of the substring, and endIndex is the last position to fetch the substring. Here the lastIndex will be the excluded.

compareTo(string): This will retunrs 0 if the both strings are equal value. If first string is greater than second one will return 1 else return negative -1 Similarly if we pass the compareTo(string,true/false) the second arg is wheather ignore case sensitive

val s1  = "Kotlin String"
val s2 = "Kotlin string"
var result: String

    println("Length of s1 string is ${s1.length}.")
      //Output : Length of s1 string is 13

    result = if (s1.compareTo(s2) == 0) "equal" else "not equal"
    println("Strings s1 and s2 are $result.")
    //Output :Strings s1 and s2 are not equal.

    var res=(s1.compareTo(s2,false))
    println("Strings s1 and s2 are $res.")
    //Output :-32 means s1 lesser than s2

    res=(s1.compareTo(s2,true))
    println("Strings s1 and s2 are $res.")
    //Output :0

    // s1.get(2) is equivalent to s1[2]
    println("Third character is ${s1.get(2)}.")
    //Output : Third character is t.

    result = s1.plus(" How are you?")
    //Output : result = Kotlin String How are you?

    println("result = $result")
    //Output : result = Kotlin String How are you?

    println("Substring is \"${s1.subSequence(4, 7)}\"")
    //Output : Substring is "in "
                            

String Equality

=== This will check the Reference of the both strings, if both are same then it will returns true

== This will check the structure of the both strings, if both are same then it will returns true

var a = "Kotlin"
var b = "Kotlin language"
var c = "Kotlin"
var d1 = "Kot"
var d2 ="lin"
var d = d1 + d2

println(a===c) // true since a and c objects point to the same String in the StringPool
println(a==c) //true since contents are equal
println(a===b) //false
println(a==b) //false
println(a===d) //false since d is made up of two different Strings. Hence a and d point to different                            set of strings
println(a==d) //true since the contents are equal