Java Programmer Skills Programme

📘LESSON 5

3.1 Lesson Outcomes

After completing this lesson, learners will be able to:

Define arrays of objects in Java.
Create objects and store them in arrays.
Access object properties from arrays.
Process arrays of objects using loops.
Explain the importance of arrays of objects in software development.

3.2 Overview

Arrays in Java are not limited to primitive data types only. Java also allows developers to store objects inside arrays. Arrays of objects are commonly used when applications need to manage groups of related entities such as students, employees, products, or customers.

This lesson introduces learners to arrays of objects and explains how object references are stored and managed within arrays. Learners will also explore how arrays of objects support data organization and simplify application development.

Arrays of objects are widely used in:

banking systems,
inventory systems,
student management systems,
healthcare applications,
and enterprise software solutions.

Understanding arrays of objects is essential because modern Java applications frequently process large collections of related objects.

KT0501 — Introduction to Arrays of Objects

An array of objects is an array that stores object references instead of primitive values.

Each element in the array refers to an object created from a class.

Example Structure

Student[] learners;

In this example:

Student is a class,
learners is an array storing Student objects.

Difference Between Primitive Arrays and Object Arrays

Primitive Arrays	Object Arrays
Store values directly	Store object references
Store simple data	Store complex data
Example: int[]	Example: Student[]

Importance of Arrays of Objects

Arrays of objects help developers:

manage grouped objects efficiently,
organize application data,
simplify object processing,
and model real-world systems.

KT0502 — Creating a Class for Object Arrays

Before creating arrays of objects, a class must first be defined.

Example Class

public class Student {

    String name;
    int marks;
}

Explanation

Component	Description
String name	Stores student name
int marks	Stores student marks

KT0503 — Creating Objects in Arrays

Objects can be created and stored inside arrays.

Example

public class Main {

    public static void main(String[] args) {

        Student[] learners = new Student[2];

        learners[0] = new Student();
        learners[1] = new Student();

        learners[0].name = "John";
        learners[0].marks = 80;

        learners[1].name = "Sarah";
        learners[1].marks = 90;

        System.out.println(learners[0].name);
        System.out.println(learners[1].name);
    }
}

Output

John
Sarah

Explanation of the Process

Step	Description
Create array	Stores object references
Create objects	Objects created using new keyword
Assign values	Store data in object properties
Access objects	Retrieve object data using indexes

KT0504 — Accessing Object Properties in Arrays

Object properties are accessed using:

array indexes,
followed by the dot operator.

Example

System.out.println(learners[0].marks);

Output

Importance of the Dot Operator

The dot operator allows access to:

variables,
methods,
and object behaviour.

KT0505 — Looping Through Arrays of Objects

Loops are commonly used to process arrays of objects.

Example Using a for Loop

public class Main {

    public static void main(String[] args) {

        Student[] learners = new Student[2];

        learners[0] = new Student();
        learners[1] = new Student();

        learners[0].name = "John";
        learners[1].name = "Sarah";

        for(int i = 0; i < learners.length; i++) {

            System.out.println(learners[i].name);
        }
    }
}

Output

John
Sarah

Enhanced for Loop Example

for(Student learner : learners) {

    System.out.println(learner.name);
}

Benefits of Looping Through Object Arrays

Looping allows developers to:

process multiple objects efficiently,
reduce repetitive code,
and simplify application logic.

KT0506 — Real-World Example of Arrays of Objects

A school management system may store:

student objects,
teacher objects,
or subject objects

inside arrays for easier management.

Example:

Student[] learners
Product[] products
Employee[] staff

Arrays of objects help organize application data into manageable structures.

3.5 Key Notes / Summary

Arrays of objects store object references.
Objects must be created before storing data.
Classes define the structure of objects.
Object properties are accessed using indexes and the dot operator.
Loops simplify processing arrays of objects.
Arrays of objects are commonly used in real-world software systems.