? Java Object Class Methods

? Quick Overview

In Java, the Object class is the root class of all classes. Every class automatically inherits methods from the Object class, even if it does not explicitly extend it.

? Key Concepts

Object class is present in java.lang package
All Java classes inherit from Object
Provides common utility methods
Methods can be overridden in subclasses

? Syntax / Theory

Some commonly used methods of the Object class are:

toString()
equals(Object obj)
hashCode()
getClass()
clone()
finalize()

? Code Example(s)

? View Code Example

// Demonstrating Object class methods
class Student {
    int id;
    String name;

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

    public String toString() {
        return id + " " + name;
    }
}

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

        System.out.println(s1.toString());
        System.out.println(s1.equals(s2));
        System.out.println(s1.getClass());
        System.out.println(s1.hashCode());
    }
}

? Live Output / Explanation

Output

1 Rahul
false
class Student
(Generated hash code value)

Explanation:

toString() returns object details
equals() compares reference by default
getClass() returns runtime class
hashCode() returns unique integer

? Interactive Lab: The "equals()" Trap

Enter data for two objects. See how equals() behaves with and without overriding.

Student s1

ID:

Name:

Student s2

ID:

Name:

Simulate: Override equals()?

Click "Run Comparison" to see results...

✅ Tips & Best Practices

Always override toString() for readable output
Override equals() and hashCode() together
Use getClass() for runtime type checks
Avoid using finalize() (deprecated)

? Try It Yourself

Override equals() to compare object values
Create two objects with same data and test equality
Print hash codes before and after overriding
Experiment with getClass() method