Mohammed mhanna

Posted on Oct 20

🧩 Understanding the Object Class in Java

#oop #java #coding #architecture

If you’ve ever wondered why every class in Java seems to have methods like toString() or equals(), the answer lies in the Object class — the ultimate parent of all classes in Java.

Let’s dive deep into what makes the Object class so fundamental and how to use it effectively.

🏛 What is the Object Class?

In Java, every class you create implicitly inherits from the Object class — even if you don’t explicitly say so.

That means this:

class MyClass {
    // extends Object implicitly
}

is the same as:

class MyClass extends Object {
}

So, every class you create automatically gains the core methods defined in Object.

🧰 Common Methods from Object

Here are the most commonly used methods that every Java class inherits:

toString()        // Returns a string representation of the object
equals(Object o)  // Compares two objects for equality
hashCode()        // Returns an integer hash code for the object
getClass()        // Returns the runtime class of the object
clone()           // Creates and returns a copy of the object (if supported)
finalize()        // Called before an object is garbage collected (deprecated)

These methods form the foundation of many features in Java — like collections, object comparison, and debugging.

🔍 Example: Using Object Methods

class Student {
    private String name;
    private int id;

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

    @Override
    public String toString() {
        return "Student{name='" + name + "', id=" + id + "}";
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) return true;
        if (!(obj instanceof Student)) return false;
        Student other = (Student) obj;
        return this.id == other.id && this.name.equals(other.name);
    }
}

public class Main {
    public static void main(String[] args) {
        Student s1 = new Student("Ali", 1);
        Student s2 = new Student("Ali", 1);

        System.out.println(s1);                   // calls toString()
        System.out.println(s1.equals(s2));        // true, because we overrode equals()
        System.out.println(s1.hashCode());        // inherited from Object (can override)
        System.out.println(s1.getClass().getName()); // Student
    }
}

🧠 Why the Object Class Exists

The Object class provides a common type for all Java objects.

That’s why you can do things like this:

Object obj = new Student("Ali", 1);

or store different types in a single collection (before generics were introduced):

List<Object> list = new ArrayList<>();
list.add("Hello");
list.add(42);
list.add(new Student("Ali", 1));

It’s what makes Java’s type system unified and consistent.

🧩 What Makes It Special

✅ It’s the root of the entire class hierarchy.

✅ It gives you default behavior for essential methods.

✅ It allows polymorphism and generic programming.

✅ It ensures every object in Java can be treated uniformly.

⚠️ A Note About finalize()

The finalize() method in Object was once used to clean up resources before an object is destroyed.

However, it’s now deprecated — unreliable and unnecessary.
👉 Use try-with-resources or explicit cleanup methods instead.

Learn more here: Oracle Docs on Finalize (deprecated)

💬 Final Thoughts

The Object class is like the invisible backbone of Java — always there, supporting everything you build.
Understanding it helps you grasp how inheritance, equality, and type systems truly work under the hood.

❓Question for You

How often do you override methods from the Object class — like equals() and toString() — in your own projects?
Share your experience in the comments 👇

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🧩 Understanding the Object Class in Java

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