break, continue & Nested Loops

Sometimes you need to leave a loop early, skip one repetition, or loop inside another loop to work with grids and combinations. break, continue and labels give you that control.

break: leave the loop

JAVA

void main() {
    int[] values = {3, 8, -1, 12, 7};
    for (int v : values) {
        if (v < 0) {
            System.out.println("Found a negative value, stopping.");
            break;
        }
        System.out.println("Processing " + v);
    }
}

Output

Processing 3
Processing 8
Found a negative value, stopping.

Searching with break

JAVA

void main() {
    String[] names = {"Lucas", "Sofia", "Mei", "Jonas"};
    int found = -1;
    for (int i = 0; i < names.length; i++) {
        if (names[i].equals("Mei")) {
            found = i;
            break;
        }
    }
    System.out.println(found >= 0 ? "Mei is at index " + found : "Not found");
}

Output

Mei is at index 2

Once you've found what you're looking for, there's no point checking the rest.

continue: skip to the next repetition

JAVA

void main() {
    for (int i = 1; i <= 10; i++) {
        if (i % 3 == 0) {
            continue;
        }
        System.out.print(i + " ");
    }
    System.out.println();
}

Output

1 2 4 5 7 8 10

continue skips the rest of the body and moves straight to the next repetition. It's useful for ignoring items that don't apply, keeping the main logic un-nested.

Nested loops

JAVA

void main() {
    for (int row = 1; row <= 4; row++) {
        for (int col = 1; col <= row; col++) {
            System.out.print("*");
        }
        System.out.println();
    }
}

Output

*
**
***
****

The inner loop runs completely for every repetition of the outer loop. Nested loops are how you work with grids, tables, pairs and combinations.

All pairs

JAVA

void main() {
    String[] players = {"Ana", "Ben", "Chloé", "David"};
    int matches = 0;
    for (int i = 0; i < players.length; i++) {
        for (int j = i + 1; j < players.length; j++) {
            System.out.println(players[i] + " vs " + players[j]);
            matches++;
        }
    }
    System.out.println(matches + " matches");
}

Output

Ana vs Ben
Ana vs Chloé
Ana vs David
Ben vs Chloé
Ben vs David
Chloé vs David
6 matches

Starting the inner loop at i + 1 avoids pairing a player with themself and listing each pair twice. Watch the cost: nested loops over n items take about n² steps, which grows quickly.

Labelled break and continue

JAVA

void main() {
    int[][] grid = {
        {1, 2, 3},
        {4, 99, 6},
        {7, 8, 9}
    };
    search:
    for (int r = 0; r < grid.length; r++) {
        for (int c = 0; c < grid[r].length; c++) {
            if (grid[r][c] == 99) {
                System.out.println("Found 99 at row " + r + ", column " + c);
                break search;
            }
        }
    }
}

Output

Found 99 at row 1, column 1

A plain break only exits the innermost loop. A label (search:) names an outer loop so break search leaves both at once. Labels are rare; often moving the loops into a method and using return is clearer.

Try it yourself

Print all prime numbers below 50, using continue on the outer loop when a divisor is found.

Output

2 3 5 7 11 13 17 19 23 29 31 37 41 43 47

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