Let us explore what does it mean to do a constructor overloading in Java. We will explore the constructor of Java with some pretty neat code examples.<\/p>\n\n\n\n
Before we dig right into the topic let us quickly revise a constructor.<\/p>\n\n\n\n
A constructor in Java is a special method that is doesn’t behave like a normal method. It doesn’t have a return type<\/strong> defined in its declaration. And it’s name must be exactly as the name of the class<\/strong>. <\/p>\n\n\n\n If we look at a normal method. It’s main purpose is to perform some action in its own instance. But a constructor’s primary function is entirely different. Having said that, you cannot use constructor as a regular method on it’s resulting instance.<\/p>\n\n\n\n So, then what exactly is a constructor ?<\/p>\n\n\n\n Are you are familiar with the new keyword in Java ? If you answered yes, then you are close to understanding what a constructor is.<\/p>\n\n\n\n The constructor is invoked whenever you create an object<\/strong> of a class<\/strong>. Yes, that is whenever you do a Let us look at a simple code snippet.<\/p>\n\n\n In the above example when we create a Now let us move to overloading the constructor.<\/p>\n\n\n\n Constructor overloading in Java can be defined as a way of having more than one constructor in a class. We can create many constructors with different parameters.<\/p>\n\n\n\n This help us initialize the object in a number of different ways. Le us look at the below class for example ( read the comments<\/strong> ).<\/p>\n\n\n As we can see that in the class above we have in total 3 constructors. In other words this is known as constructor overloading.<\/p>\n\n\n\n And we have 3 constructor overloads. Next let us understand why do we require constructor overloading in Java.<\/p>\n\n\n\n Now that we have seen how we do constructor overloading. Let us understand why do we need constructor overloading in Java.<\/p>\n\n\n\n We use constructor overloading approach in Java to initialize the object in multiple different ways. It adds some flexibility to the object construction.<\/p>\n\n\n\n Let’s say you need to set the values while the object is being created like in the examples explained below. Then constructor overloading is a desirable approach.<\/p>\n\n\n\n As we can see in the code example above. We have multiple constructors initializing the object in multiple ways.<\/p>\n\n\n\n For instance let us take an example of And So that was a quick explanation about constructor overloading. Keep learning and coding.<\/p>\n\n\n\n Suggested<\/strong><\/p>\n\n\n\n Java List Data Structure: Learn Real Use Case Of List<\/a><\/p>\n\n\n\n ArrayList in Java: Understand With Example<\/a><\/p>\n\n\n\n Run Length Encoding in Java: Learn How To Implement<\/a><\/p>\n\n\n\nnew YourClassName();<\/code>. In other words it is used to initialize the instance of an object.<\/p>\n\n\n\npublic<\/span> class Person<\/span>()<\/span> <\/span>{\n\n public<\/span> Person<\/span>()<\/span> <\/span>{\n\n \/\/ 2. this is the constructor in Java.<\/span>\n }\n\n}\n\n\/\/ 1. creating a new instance of the class above<\/span>\nPerson p = new<\/span> Person();<\/code><\/span>Code language:<\/span> Java<\/span> (<\/span>java<\/span>)<\/span><\/small><\/pre>\n\n\nnew Person()<\/code> the constructor method is invoked. And that sums up our constructor revisit.<\/p>\n\n\n\nWhat is constructor overloading in Java ?<\/h2>\n\n\n\n
public class<\/span> Person<\/span>() <\/span>{\n\n private int age;\n private String<\/span> firstName;\n private String<\/span> lastName;\n private String<\/span> occupation;\n\n public Person(String<\/span> firstName, String<\/span> lastName, int age, String<\/span> occupation) {\n\n \/\/ Constructor No. 1<\/span>\n\n this<\/span>.firstName = firstName;\n this<\/span>.lastName = lastName;\n this<\/span>.age = age;\n this<\/span>.occupation = occupation;\n }\n\n public Person(String<\/span> name, int age) {\n\n \/\/ Constructor No. 2<\/span>\n\n \/\/ we can overload constructor by only accepting required arguments <\/span>\n \/\/ in case of this example we will accept only 2 arguments<\/span>\n \/\/ and we will fill in other details here without any issue<\/span>\n\n firstName = name;\n this<\/span>.age = age;\n\n lastName = \"\"<\/span>; \/\/ fill in empty last name<\/span>\n occupation = \"Unemployed\"<\/span>; \/\/ set desired occupation<\/span>\n\n }\n\n public Person(String<\/span> name) {\n\n \/\/ Constructor No. 3<\/span>\n\n \/\/ we can also add another constructor that accepts only one argument<\/span>\n \/\/ let us supply only the name of the person and fill in other details here.<\/span>\n\n firstName = name;\n\n lastName = \"\"<\/span>; \/\/ empty<\/span>\n occupation = \"Student\"<\/span>; \/\/ everyone is studying<\/span>\n age = 20<\/span>; \/\/ every person object created with this constructor will be 20 year old<\/span>\n }\n\n}<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\nWhy use constructor overloading in Java ?<\/h2>\n\n\n\n
Constructor No. 3<\/code>. It’s obvious from the constructor that the resulting object is a Student<\/code>.<\/p>\n\n\n\nConstructor No. 2<\/code> is used when we want to create a person who is Unemployed<\/code>.<\/p>\n\n\n\n