What is the difference between constructor and method?

The main difference between constructor and method is that a constructor is a special method in a class that initializes the objects of that class whereas a method is a procedure or a function that executes a set of instructions associated with a class.

Most high-level programming languages ​​support Object Oriented Programming (OOP), which is a methodology that allows programmers to model real-world scenarios in computing to solve problems. The constructor and the method are related to the OOP. Constructor is a special type of method while a method is a block of statements.

Key Areas Covered

1. What is constructor
     – Definition, Functionality
2. What is method
     – Definition, Functionality
3. What is the difference between constructor and method?
     – Comparison of key differences

Key terms

Class, Constructor, Method, Object, OOP

what is constructor

A constructor is a special type of method that helps initialize an object on creation. Also, both the class and the constructor have the same name. However, there is no return type in the constructor. Typically, programmers use constructors to give initial values ​​to instance variables defined in the class. If the constructor is not defined by the programmer, the program automatically calls the default constructor. All member variables will be initialized to zero. But, if the programmer writes his own constructor, then he won’t use the default constructor.

Figure 1: Program with Builder

In the employee class above, there is a constructor called employee. There are two instance variables like id and name. On line 8, there is a constructor, which has the same name as the class name. Initialize the id and name. In the main program, an employee object is created. Finally, the id and name values ​​appear in the console. 

What is the method

A method is a set of instructions to perform a certain operation. Using methods in the program makes it more manageable. It is possible to call the relevant method when necessary. Also, each method has a name to identify it. And, a method can accept a parameter or not. After performing the task, the method can return a value. Here, if the method returns an integer, the return type is int. But, if the method returns nothing, then the return type is null.

Figure 2: Program with Method

In the above program, an object of class MaxFind is created. That object calls the maxValue method. Gets two values. The methods check the values ​​and return the maximum value. It will store the maximum value in a variable named max. Finally, the maximum value obtained is printed to the console. MaxValue is a method and finds the maximum value of these two numbers.

Difference Between Constructor and Method

Definition

A constructor is a special method that usually has the same name as the class, and we can use it to set the values ​​of an object’s members to default or user-defined values. Whereas, a method is a programmed procedure that is defined as part of a class and is included in any object of that class. These definitions give an idea of ​​the fundamental difference between constructor and method.

return type

To add to this, the constructor has no return type while the method may or may not return a value. Hence, this is another difference between constructor and method.

Flaw

An important difference between constructor and method is that the default constructor will be called by the program in case the programmer does not write a constructor. However, there are no default methods.

Name

A constructor has the same name as the class name, while a method can have any name other than the keywords.

Invocation

Another difference between constructor and method is that constructors invoke implicitly while methods invoke explicitly.

Use

Also, the constructor helps to initialize an object while a method helps to exhibit the functionality of an object.

conclusion

The constructor and the method are related to the OOP. The main difference between constructor and method is that a constructor is a special method in a class that initializes the objects of that class while a method is a procedure or a function that executes a set of instructions associated with a class.

Reference:

1. “Java Methods.” Www.tutorialspoint.com, available here.
2. “Java Constructors.” Www.tutorialspoint.com, available here.