Java Academy · Lesson

Array Basics & Iteration

Understand array basics: fixed-size, zero-based indexing, create/initialize, and iterate safely.

What is an array

Array is a fixed-size sequence of elements of the same type, stored under one name and indexed from 0.

Use when you know the element count
Access by index: first is 0
Type-safe: all items have the same type

Declare & Create

Declare and create arrays:

public class Main {
  public static void main(String[] args) {
    // Way 1: Declare an array with fixed size
    int[] a = new int[3];
    // All elements are 0 by default: [0, 0, 0]

    // Way 2: Declare and initialize in one line
    int[] b = {10, 20, 30};
    // This array already has values: [10, 20, 30]

    // Print both arrays
    System.out.print("Array a: ");
    for (int i = 0; i < a.length; i++) {
      System.out.print(a[i] + " ");
    }

    System.out.println(); // new line

    System.out.print("Array b: ");
    for (int i = 0; i < b.length; i++) {
      System.out.print(b[i] + " ");
    }
  }
}

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