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Source: Dev.to

Java Concepts I’m Mastering – Part 4: Constructor vs Method

What is a Constructor?

A constructor is a special block of code that:

• Has the same name as the class
• Is called automatically when an object is created
• Initializes object data

class Student {
    String name;

    Student(String name) {   
        this.name = name;
    }
}

It runs when you create an instance:

Student s1 = new Student("Kanishka");

What is a Method?

A method:

• Has a return type (or void if it returns nothing)
• Is called explicitly by the code
• Performs actions on the object’s data

class Student {
    String name;

    void display() {   
        System.out.println(name);
    }
}

It runs only when you invoke it:

s1.display();

Key Differences

• Purpose: Constructors build/initialize the object; methods define its behavior.
• Invocation: Constructors are invoked automatically with new; methods require an explicit call.
• Naming: Constructor name must match the class name; method names are independent.
• Return Type: Constructors have no return type; methods declare one (or void).

What I Learned

• Constructors build the object.
• Methods define its behavior.
• Clean class design depends on understanding both.

Next in the series

Method Overloading in Java.