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1. Introduction

So far, we have seen arrays that store primitive data types such as:

int[]
double[]
char[]

But Java is an object-oriented language, and in real applications, data is often represented using objects, not primitives.

Example:

Student objects
Employee objects
Product objects
Book objects

To store multiple objects, Java allows arrays of objects.

2. What Is an Array of Objects?

An array of objects is an array where each element is a reference to an object, not the object itself.

Example:

Student[] students = new Student[3];

This creates space to store 3 references, but not the actual Student objects yet.

3. Creating an Array of Objects

Using a simple Student class:

class Student {
    String name;
    int age;
}

Step 1: Declare and create the array

Student[] students = new Student[3];

Memory created:

students[0] → null
students[1] → null
students[2] → null

Because the objects are not created yet.

Step 2: Create objects manually

students[0] = new Student();
students[1] = new Student();
students[2] = new Student();

Then assign values:

students[0].name = "Amit";
students[0].age = 20;

students[1].name = "Sara";
students[1].age = 22;

students[2].name = "John";
students[2].age = 21;

4. Complete Example

class Student {
    String name;
    int age;
}

public class Main {
    public static void main(String[] args) {

        Student[] students = new Student[3];

        students[0] = new Student();
        students[1] = new Student();
        students[2] = new Student();

        students[0].name = "Amit";
        students[0].age = 20;

        students[1].name = "Sara";
        students[1].age = 22;

        students[2].name = "John";
        students[2].age = 21;

        for (Student s : students) {
            System.out.println(s.name + " - " + s.age);
        }
    }
}

Output:

Amit - 20
Sara - 22
John - 21

Image prompt

A diagram showing an array with 3 cells: [0] [1] [2] each cell containing a reference arrow pointing to a Student object box (with fields name and age). Clean OOP visualization.

array-of-object

5. Initializing Array of Objects Directly

Instead of creating objects separately, you can initialize in one line:

Student[] students = {
    new Student("Amit", 20),
    new Student("Sara", 22),
    new Student("John", 21)
};

But the constructor must exist:

class Student {
    String name;
    int age;

    Student(String name, int age) {
        this.name = name;
        this.age = age;
    }
}

6. Iterating Over Array of Objects

Using Enhanced For Loop

for (Student s : students) {
    System.out.println(s.name);
}

Using Index Loop

for (int i = 0; i < students.length; i++) {
    System.out.println(students[i].age);
}

7. Important Notes

7.1 Array Stores References, Not Objects

This is crucial:

Student[] arr = new Student[3];

This does not create 3 objects.

It creates 3 null references.

Objects must be created separately.

7.2 NullPointerException Risk

If you forget to create objects:

Student[] arr = new Student[2];
arr[0].name = "Amit"; // ERROR!

Fix:

arr[0] = new Student();

7.3 Array of Objects vs ArrayList

Arrays are fixed size. ArrayList grows automatically.

Example:

ArrayList<Student> list = new ArrayList<>();
list.add(new Student("Amit", 20));

ArrayList is preferred in real-world applications.

Image prompt

A comparative diagram: Left → Array with fixed size storing object references Right → ArrayList dynamically growing with add()

array-of-object

8. Real-World Example: Product List

class Product {
    String name;
    int price;

    Product(String name, int price) {
        this.name = name;
        this.price = price;
    }
}

public class Demo {
    public static void main(String[] args) {

        Product[] products = {
            new Product("Laptop", 50000),
            new Product("Mouse", 700),
            new Product("Keyboard", 1500)
        };

        for (Product p : products) {
            System.out.println(p.name + " - " + p.price);
        }
    }
}

9. Summary

Java arrays can store object references.
Creating an array does not create objects — only references.
Objects must be created individually or using array literals.
Arrays of objects work like primitive arrays, but each element holds a reference.
Useful for grouping related objects (students, employees, products).
In real-world applications, ArrayList is more flexible.

Written By: Shiva Srivastava

Array of Objects

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