java constructor with parameters example

#Java constructor with parameters example how to#

There are two types of constructors in Java: no-arg constructor, and parameterized constructor. In such case, Java compiler provides a default constructor by default. It calls a default constructor if there is no constructor available in the class. It is a special type of method which is used to initialize the object.Įvery time an object is created using the new() keyword, at least one constructor is called. At the time of calling constructor, memory for the object is allocated in the memory. It is called when an instance of the class is created. In Java, a constructor is a block of codes similar to the method.

Does constructor perform other tasks instead of the initialization.

Copying the values of one object into another.

Concepts like constructors are simple but are extremely important as they involve classes and objects.

#Java constructor with parameters example how to#

Now that you have a grip on what constructors are and how to work with them, you are one step closer on your journey to learn Java. Rectangle obj2 = new Rectangle(2,4,'Green') ('Length-' + length + 'Breadth-' + breadth+ 'Color' + color) Based on different types or number of arguments, different constructors will be called.Įxample illustrating Constructor Overloading: Constructor OverloadingĬonstructor supports method overloading just like any other class. The default constructor initializes “member” variable to “YES” and then continues to execute parameterized constructor. In the above example, when parameterized constructor in invoked, it first calls the default constructor with the help of this() keyword. (studentName + ' -' + studentAge+ '-'+ 'Member' + member) * this is used for calling the default constructor this keyword fulfills this purpose.Įxample illustrating call to a default constructor from a parameterized constructor: Sometimes there is a need to call the default constructor from another constructor of the same class. Calling Default Constructor From A Parameterized Constructor in Java Finally, when we print both object’s studentName variable using display function we get “Manan”. We then pass obj1 as an argument while creating obj2. In the above example, we initialize obj1 using a string. * passing the object as an argument for the constructor In this way parameterized constructors fulfills the need to copy one object’s values to another.Įxample illustrating Passing Objects as Arguments: We can also pass arguments while creating other instances of a class. With a parameterized constructor for a class, one must provide initial values as arguments, otherwise, the compiler reports an error. Display method then gives the desired output. The constructor then initializes studentName and studentAge using the passed values. In the above example, we are passing a string and an integer to the object. (studentName+ ' '+studentAge) Įdureka myObj = new Edureka('Manan', 19)

To initialize data members of a class with distinct values.Įxample illustrating Parameterized Constructor: Parameterized Constructor – A constructor is called Parameterized Constructor when it accepts a specific number of parameters. It is used to initialize an object’s data members.Įdureka() Calling Default Constructor From A Parameterized ConstructorĪ constructor is basically a method that is automatically called when an object(instance) is created of that class.Default Constructor vs Parameterized Constructor.

Please note that a basic understanding of classes and objects is required before you continue to constructors. In this article we will particularly look at how to initialize an object using parameterized constructors in Java. The core of all the OOP features is the implementation of Classes and Objects and their interaction with one another. That means while programming in Java we have all the powerful features of Data Abstraction, Polymorphism, Inheritance etc. Java is one of the many programming languages which follows Object Oriented Approach.