Difference between Constructor and Method in Java

Java is an Object-Oriented Programming language. Therefore, the data and the member functions in Java are present in the classes. The classes in Java contain both constructors and methods as well. Let’s see in detail about methods and constructors and their differences.

Constructor

The purpose of constructors is to initialize the objects, which are the instances of the classes. Similar to the methods, the constructors also hold statement blocks that get executed during the run time of the program. Constructors are compulsory in Java. Even though you don’t make one, the Java compiler adds a default constructor in your program. Whenever you create an object with the new() keyword, one constructor always gets invoked.

Example:

class HelloConstructor { 

    int num; 

    String name; 

  

    // This is the constructor with a statement block

    HelloConstructor() 

    { 

        System.out.println("Constructor called"); 

    } 

} 

  

class ConstructorCalling { 

    public static void main (String[] args) 

    { 

        // this would invoke default constructor. 

        HelloConstructor helloConstructor = new HelloConstructor(); 

  

        // Default constructor provides the default 

        // values to the object like 0, null 

        System.out.println(helloConstructor.name); 

        System.out.println(helloConstructor.num); 

    } 

}

Output:

Constructor called
null
0

Method

Methods in Java are a collection of statements that get executed during the run time. The statements inside the methods block perform some particular task and then return an outcome to the caller. It is not compulsory for the method to always return something. The purpose of member functions is the reusability of the code. In Java, a function is always a part of a class, unlike in other languages like C++ and C.

Example:

class Add { 
	int sum = 0; 
	public int addTwoNo(int a, int b) 
	{ 
		// Adding two integer value. 
		sum = a + b; 
		// Returning summation of two values. 
		return sum; 
	} 
} 

class Sum { 
	public static void main(String[] args) 
	{ 

		// Creating an instance of Addition class 
                // Default constructor is called here
		Add add = new Add(); 

		// Calling addTwoInt() method to add two integer 
		int sum = add.addTwoNo(3, 2); 

		System.out.println("Sum of two integers is: "
						+ sum); 
	} 
}

Output:

Sum of two integers is: 5

Now let’s see the points that make the methods and constructors different from each other:

Comment down below if you have any queries related to the above article.