for-each

Learn to iterate arrays and collections with for-each.

for-each

The for-each loop walks through each element of an array or collection in order. No index is needed:

int[] nums = {10, 20, 30};
for (int n : nums) {
    System.out.println(n);
}

Here n takes one element of the array each turn: 10, 20, 30. for-each is shorter and has no risk of going past the end. It is ideal for read-only use; when you need to modify an element by index, use the classic for.

for-each vs for

The classic for gives an index; for-each gives the element itself. Both walk an array:

String[] names = {"Ayşe", "Alex"};
// Classic for
for (int i = 0; i < names.length; i++) {
    System.out.println(names[i]);
}
// for-each
for (String name : names) {
    System.out.println(name);
}

If no index is needed, for-each is cleaner. The array length is read with names.length (no parentheses).

Exercise Sum the numbers

Write a Main class with a main method. Assign {5, 10, 15} to int[] nums. Assign 0 to int sum. With for (int n : nums) add each n to sum (sum += n). Finally print System.out.println(sum).

Show example solution

public class Main {
    public static void main(String[] args) {
        int[] nums = {5, 10, 15};
        int sum = 0;
        for (int n : nums) {
            sum += n;
        }
        System.out.println(sum);
    }
}

Test yourself

Complete the for-each

int[] nums = {1, 2, 3};
for (int n ____ nums) {
    System.out.println(n);
}

Show answer

int[] nums = {1, 2, 3};
for (int n : nums) {
    System.out.println(n);
}

Match the for-each concepts

for

Loop
:

Separator
nums

Array
int n

Element
When is for-each preferred?
- When an index is needed
- To break the loop
- To read each element
- For infinite loops
Show answer

To read each element — for-each is ideal for reading each element.

Next lesson: Summary - Loops

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