Object Class

Object Class

• The Object class is the root class of all classes in Java.
• Every class in Java implicitly extends the Object class unless explicitly specified otherwise.
• Commonly used methods include toString() and equals().

toString() Methodequals() Method

• The toString() method returns a string representation of the object.
• By default, it returns the class name followed by the @ symbol and the hash code of the object.
• It is often overridden to provide a meaningful string representation of the object.

class Example {
    int id;
    String name;

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

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

• The equals() method is used to compare two objects for equality.
• By default, it checks if two references point to the same object (reference equality).
• It is often overridden to compare the content of objects (value equality).

class Example {
    int id;
    String name;

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

    @Override
    public boolean equals(Object obj) {
        if (this == obj) return true; // Check if references are the same
        if (obj == null || getClass() != obj.getClass()) return false; // Check class type
        Example example = (Example) obj;
        return id == example.id && name.equals(example.name); // Compare fields
    }
}

public class Main {
    public static void main(String[] args) {
        Example obj1 = new Example(1, "John");
        Example obj2 = new Example(1, "John");
        Example obj3 = new Example(2, "Doe");

        System.out.println(obj1.equals(obj2)); // Outputs: true
        System.out.println(obj1.equals(obj3)); // Outputs: false
    }
}