Kotlin break Statement

Introduction

The break statement in Kotlin is used to terminate the nearest enclosing loop immediately, regardless of the loop condition. This is useful when you want to exit a loop based on a specific condition before the loop would naturally terminate. This chapter will cover the syntax and usage of the break statement in Kotlin with examples.

Basic break Statement

The break statement can be used inside any loop (for, while, or do-while). When the break statement is executed, the loop is terminated, and control is transferred to the statement immediately following the loop.

Syntax

break

Example with for Loop

fun main() {
    for (i in 1..10) {
        if (i == 5) {
            break
        }
        println("Iteration $i")
    }
    println("Loop terminated")
}

Explanation:

• The loop iterates from 1 to 10.
• When i equals 5, the break statement is executed, and the loop terminates.
• The output will be:

  Iteration 1
  Iteration 2
  Iteration 3
  Iteration 4
  Loop terminated
  

Example with while Loop

fun main() {
    var i = 1
    while (i <= 10) {
        if (i == 5) {
            break
        }
        println("Iteration $i")
        i++
    }
    println("Loop terminated")
}

Explanation:

• The loop iterates while i is less than or equal to 10.
• When i equals 5, the break statement is executed, and the loop terminates.
• The output will be:

  Iteration 1
  Iteration 2
  Iteration 3
  Iteration 4
  Loop terminated
  

Example with do-while Loop

fun main() {
    var i = 1
    do {
        if (i == 5) {
            break
        }
        println("Iteration $i")
        i++
    } while (i <= 10)
    println("Loop terminated")
}

Explanation:

• The loop iterates while i is less than or equal to 10.
• When i equals 5, the break statement is executed, and the loop terminates.
• The output will be:

  Iteration 1
  Iteration 2
  Iteration 3
  Iteration 4
  Loop terminated
  

Nested Loops

When using nested loops, the break statement only terminates the nearest enclosing loop. To break out of multiple nested loops, you can use labels.

Example with Nested Loops

fun main() {
    for (i in 1..3) {
        for (j in 1..3) {
            if (i == 2 && j == 2) {
                break
            }
            println("i = $i, j = $j")
        }
    }
    println("Loop terminated")
}

Explanation:

• The outer loop iterates from 1 to 3.
• The inner loop iterates from 1 to 3 for each iteration of the outer loop.
• When i equals 2 and j equals 2, the break statement is executed, and only the inner loop terminates.
• The output will be:

  i = 1, j = 1
  i = 1, j = 2
  i = 1, j = 3
  i = 2, j = 1
  Loop terminated
  

Labeled break Statement

To break out of multiple nested loops, you can use labeled break statements. A label is defined by placing an identifier followed by @ before the loop.

Syntax

label@ for (item in collection) {
    for (subItem in subCollection) {
        if (condition) {
            break@label
        }
    }
}

Example with Labeled break

fun main() {
    outer@ for (i in 1..3) {
        for (j in 1..3) {
            if (i == 2 && j == 2) {
                break@outer
            }
            println("i = $i, j = $j")
        }
    }
    println("Loop terminated")
}

Explanation:

• outer@ is a label for the outer loop.
• When i equals 2 and j equals 2, the break@outer statement is executed, and both the inner and outer loops terminate.
• The output will be:

  i = 1, j = 1
  i = 1, j = 2
  i = 1, j = 3
  i = 2, j = 1
  Loop terminated
  

Conclusion

In this chapter, you learned about the break statement in Kotlin, including its syntax and usage to terminate loops prematurely. You also saw examples of using the break statement in for, while, and do-while loops, as well as handling nested loops with labeled break statements. Understanding how to use the break statement is essential for controlling the flow of your Kotlin programs and managing loops effectively.