Summarize of Kotlin String.

3. String

1. String Equality

String are compared with == operator with check for their structural equality.

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val str1 = "Hello, World"
val str2 = "Hello," + " World"
println(str1 == st2)    // print true

Referential equality is checked with === operator.

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val str1 = """
 |Hello, World!
 """.trimMargin()
val str2 = """
 #Hello, World!
 """.trimMargin("#")
val str3 = str1

println(str1 == str2) // Prints true
println(str1 === str2) // Prints false
println(str1 === str3) // Prints true

2. String Literals

Kotlin has two types of string literals:

  • Escaped string
  • Raw string

Escaped string handles special characters by escaping them. The following escape sequences are supported: \t, \b, \n, \r, \', \", \\ \$, also use Unicode \uFF00.

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val a = "Hello \n Hello"
val b = "Hello \t Hello"
val c = "Hello \b Hello"
val d = "Hello \r Hello"
val e = "Hello \' Hello"
val f = "Hello \" Hello"
val g = "Hello \\ Hello"
val h = "Hello \$ Hello"

The result is like below.

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Hello
 Hello
Hello 	 Hello
Hello Hello
 Hello
Hello ' Hello
Hello " Hello
Hello \ Hello
Hello $ Hello

Raw string delimited by """".

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val text = """
 for (c in "foo")
 print(c)
"""

Leading whitespace can be removed with trimMargin() function.

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val text = """
 |Tell me and I forget.
 |Teach me and I remember.
 |Involve me and I learn.
 |(Benjamin Franklin)
 """.trimMargin()

3. Elements of String

Element of String are characters that can be accessed by the indexing operation string[index].

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val str = "Hello, World!"
println(str[1])

String elements can be iterated with a for loop.

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for(x in str){
    println(x)
}

4. String Templates

String template starts with a dollar sign $ and consists of either a variable name:
Or an arbitrary expression in curly braces:

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val i = 10
val s = "i = $i"

val a = "abc"
val str = "$a.length is ${a.length}" // "abc.length is 3"