Labeled break and continue in Kotlin - Step-by-Step Execution

Concept Flow - Labeled break and continue

Start Outer Loop

↓

Start Inner Loop

↓

Check Condition

↓

Labeled break or continue

↓

Exit or Continue Loops

↩Back to Outer Loop or Exit

The program runs nested loops. Inside, it checks a condition to decide whether to break or continue a specific loop using labels.

Execution Sample

Kotlin

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

This code uses a labeled break to exit the outer loop when i and j both equal 2.

Execution Table

Step	i	j	Condition (i==2 && j==2)	Action	Output
1	1	1	false	Print i=1, j=1	i=1, j=1
2	1	2	false	Print i=1, j=2	i=1, j=2
3	1	3	false	Print i=1, j=3	i=1, j=3
4	2	1	false	Print i=2, j=1	i=2, j=1
5	2	2	true	break@outer (exit outer loop)
6	-	-	-	Exit loops

💡 At step 5, condition is true, so break@outer exits the outer loop and stops all looping.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5	Final
i	-	1	1	1	2	2	-
j	-	1	2	3	1	2	-

Key Moments - 2 Insights

Why does the program stop completely at step 5 instead of just breaking the inner loop?

Because the break uses the label 'outer', it exits the outer loop, not just the inner one. See step 5 in the execution_table where break@outer is used.

What would happen if we used 'continue@outer' instead of 'break@outer' at step 5?

The program would skip the rest of the current outer loop iteration and start the next one. It would not exit all loops. This changes the flow after step 5.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of 'j' at step 3?

A 2

B 1

C 3

D 4

💡 Hint

Check the 'j' column in the execution_table row for step 3.

At which step does the labeled break cause the loops to exit?

A Step 4

B Step 5

C Step 6

D Step 3

💡 Hint

Look at the 'Action' column in the execution_table to find where break@outer happens.

If the condition was never true, how many times would 'println' run?

A 9 times

B 6 times

C 3 times

D 0 times

💡 Hint

Consider the nested loops from 1 to 3 for both i and j, and check the output count in execution_table.

Concept Snapshot

Labeled break and continue in Kotlin:
- Use labels to specify which loop to break or continue.
- Syntax: label@ for loops, then break@label or continue@label.
- break@label exits the labeled loop immediately.
- continue@label skips to next iteration of labeled loop.
- Useful in nested loops to control flow precisely.

Full Transcript

This example shows how Kotlin uses labeled break to exit an outer loop from inside an inner loop. The outer loop runs i from 1 to 3, and the inner loop runs j from 1 to 3. When both i and j equal 2, the condition triggers break@outer, which stops all looping immediately. The execution table tracks each step, showing variable values and actions. The variable tracker shows how i and j change over time. Key moments clarify why labeled break exits the outer loop, not just the inner one. The quiz tests understanding of variable values and loop control flow. The concept snapshot summarizes how labeled break and continue work in Kotlin for nested loops.