How to Iterate 2D Array in Java: Syntax and Examples

To iterate a 2D array in Java, use nested for loops where the outer loop goes through rows and the inner loop goes through columns. Access each element with array[row][column] inside the loops.

Syntax

Use two nested for loops: the outer loop iterates over rows, and the inner loop iterates over columns. Access elements with array[i][j].

• i: index for rows
• j: index for columns
• array[i][j]: element at row i and column j

java

for (int i = 0; i < array.length; i++) {
    for (int j = 0; j < array[i].length; j++) {
        // Access element
        System.out.println(array[i][j]);
    }
}

Example

This example shows how to print all elements of a 2D integer array using nested loops.

java

public class Iterate2DArray {
    public static void main(String[] args) {
        int[][] numbers = {
            {1, 2, 3},
            {4, 5, 6},
            {7, 8, 9}
        };

        for (int i = 0; i < numbers.length; i++) {
            for (int j = 0; j < numbers[i].length; j++) {
                System.out.print(numbers[i][j] + " ");
            }
            System.out.println();
        }
    }
}

Output

1 2 3 
4 5 6 
7 8 9 

Common Pitfalls

Common mistakes include:

• Using the wrong loop limits, like array.length for both loops, which fails if rows have different lengths.
• Confusing row and column indexes.
• Not initializing the 2D array properly before iterating.

Always use array[i].length for the inner loop to handle uneven rows safely.

java

int[][] arr = {{1, 2}, {3, 4, 5}};

// Wrong: assumes all rows have same length
for (int i = 0; i < arr.length; i++) {
    for (int j = 0; j < arr.length; j++) { // should be arr[i].length
        System.out.print(arr[i][j] + " ");
    }
    System.out.println();
}

// Right:
for (int i = 0; i < arr.length; i++) {
    for (int j = 0; j < arr[i].length; j++) {
        System.out.print(arr[i][j] + " ");
    }
    System.out.println();
}

Quick Reference

• Use array.length for number of rows.
• Use array[i].length for number of columns in row i.
• Access elements with array[i][j].
• Nested loops are needed to visit every element.

Key Takeaways

Use nested for loops to iterate rows and columns of a 2D array in Java.

Always use array[i].length for the inner loop to handle rows with different lengths.

Access elements with array[i][j] inside the loops.

Avoid using the same length for both loops if the 2D array is jagged.

Initialize your 2D array properly before iterating.