What is use constructor and destructor in java

Safalta Expert Published by: Vanshika Jakhar Updated Tue, 22 Nov 2022 11:19 PM IST

The creation of constructors and destroyers in Java is covered in detail in the article that follows. There is a constructor and destroyer concept found in all programming languages. Java is a language for object-oriented programming. It will be advantageous to comprehend them more clearly if you are familiar with object-oriented concepts. Destructors are used to undo the initialization that a constructor created for an object.

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Automatic garbage collection is available in Java and uses the algorithm of Mark and Sweep. Click here to learn more https://www.safalta.com/data-science-with-python-classes

Table of Content
What are constructors and destroyers in Java?
Why are constructors and destroyers necessary in Java?
How Java's Constructor and Destructor Function
Types of Constructor
Finalize() methods

What are constructors and destroyers in Java?

When a variable is initialized, a constructor allocates memory for that variable. An object's automatic initialization is all that a constructor does. When an object is created by the program, the constructor is automatically called. The memory allotted during initialization is released using the destructor. In Java, we typically don't need to explicitly call the destructor. Java has an automated garbage collection component.

Why are constructors and destroyers necessary in Java?

The main purposes of constructors and destroyers are to efficiently handle memory allocation and de-allocation.

In any programming language, constructors and destroyers play a crucial role in initializing and eradicating objects after use to free up memory.

How Java's Constructor and Destructor Function

In Java, a constructor is simply a method with the same name as the class. There is no return type for the constructor method.

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Types of Constructor

There are two different types of constructors, and we can add and remove variables according to the type.

  • Default Constructor
  • Parameterized Constructor

1. Default Constructor

This particular constructor type exists. By default, this runs without any parameters. There aren't any parameters in this function.

2. Parameterized Constructor

The parameterized constructor, as the name suggests, takes some arguments or parameters when initializing the object.

In Java, constructor overloading refers to the use of multiple constructors with various parameter values. This allows each constructor to perform a variety of tasks. Depending on the situation, we may need to initialize constructors in a variety of ways.


There is no destructor in Java, so let me say that before we talk about it. The C++ programming language has destructors. In the case of Java, this feature is known as the automatic garbage collector. which, when not in use, free the dynamically allocated memory. This idea is crucial, and Java allows you to learn more about garbage collection.

  • Java automatically allocates memory using the garbage collection technique.
  • Destructors don't need to be used explicitly, like in C++.
  • In contrast to C programming, Java does not have a malloc function for memory allocation.
  • The same memory allocation process is carried out by Java's new operator.
  • The new keyword allocates heap memory for an object.
  • A new keyword allocates memory for the object at the time of execution. The program manages memory allocation, so the end user doesn't need to worry about it. The memory used for the object is put to use for another task once the object used in programs has finished its work. Garbage collection in Java handles the task of effectively using memory.

Then, let's discuss the destroyer. As far as we know, Java does not have a destructor because it has a finalize() method for doing so. The following are some of the most important things to remember:

Finalize() methods:

  • As we've already seen, the finalize method functions as the opposite of a constructor and similarly to a destructor.
  • Typically, the object is removed using the finalize method.
  • We must explicitly define this method in Java before we can use it.
  • After garbage collection has finished, the finalized method gets to work.
  • This simply means that there is a chance that memory usage with other things like fonts and other items still exists after freeing memory space by deallocating memory from objects.

What is the purpose of constructor and destructor in Java?

While the destructor is used to delete or destroy an object, which releases the resource it was using, the constructor is used to initialise objects. Keep in mind that Java does not have the concept of a destructor. Java offers the garbage collector in place of the destructor, which performs the same function.

What is the difference between a constructor and a destructor?

A constructor is one of a class's member functions with the same name as the class itself. Initializing a class's object is helpful. Whereas destructor is used to destroy the instances.

Why do we need a destructor in OOP?

A destructor in object-oriented programming provides an object with one final opportunity to free up any memory it allocated or complete any other tasks before the object is destroyed. Destructors are defined in the class definition as subroutines, just like constructors.

Can Java constructors and destructors be overloaded?

Yes! Java permits the overloading of constructors. When loading the constructor, we create multiple constructors with the same name but various parameter types or numbers.

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