How to Create Array in Java: Syntax and Examples

In Java, you create an array by declaring its type followed by square brackets [] and then initializing it with a size or values using new keyword or curly braces. For example, int[] numbers = new int[5]; creates an integer array of size 5.

Syntax

To create an array in Java, you first declare the type of elements it will hold, followed by square brackets []. Then, you initialize the array either by specifying its size with new or by directly assigning values using curly braces.

• Declaration: type[] arrayName;
• Initialization with size: arrayName = new type[size];
• Initialization with values: arrayName = new type[]{value1, value2, ...}; or type[] arrayName = {value1, value2, ...};

java

int[] numbers = new int[5];
String[] names = {"Alice", "Bob", "Charlie"};

Example

This example shows how to create an integer array, assign values, and print them using a loop.

java

public class ArrayExample {
    public static void main(String[] args) {
        int[] numbers = new int[3];
        numbers[0] = 10;
        numbers[1] = 20;
        numbers[2] = 30;

        for (int i = 0; i < numbers.length; i++) {
            System.out.println("Element at index " + i + ": " + numbers[i]);
        }
    }
}

Output

Element at index 0: 10
Element at index 1: 20
Element at index 2: 30

Common Pitfalls

Common mistakes when creating arrays in Java include:

• Forgetting to specify the size when using new, which causes a compile error.
• Trying to change the size of an array after creation, which is not allowed.
• Accessing indexes outside the array bounds, causing ArrayIndexOutOfBoundsException.
• Confusing array declaration syntax, such as placing brackets after the variable name instead of the type.

java

/* Wrong: missing size or values */
// int[] arr = new int[]; // Error: size or values needed

/* Right: specify size or values */
int[] arr1 = new int[3];
int[] arr2 = {1, 2, 3};

Quick Reference

Action	Syntax Example
Declare array	int[] numbers;
Create array with size	numbers = new int[5];
Create and initialize array	int[] nums = {1, 2, 3};
Access element	int x = numbers[0];
Get length	int len = numbers.length;

Key Takeaways

Declare arrays with the element type followed by square brackets, like int[].

Initialize arrays with new type[size] or directly with values in curly braces.

Array size is fixed after creation and cannot be changed.

Always access array elements within valid index range to avoid errors.

Use array.length to get the number of elements in the array.