What Is Constructor Overloading Inwards Java? - Interview Question

Constructor overloading inwards java allows having more than i constructor within i Class. inwards the concluding article nosotros have discussed method overloading together with overriding together with constructor, overloading is non much unlike than method overloading. Just similar inwards the instance of method overloading yous lead hold multiple methods amongst the same advert but different signature, inwards Constructor overloading yous lead hold multiple constructors amongst a unlike signature amongst the solely difference that Constructor doesn't lead hold a render type inwards Java. That constructor volition survive called equally an overloaded constructor . Overloading is likewise roughly other shape of polymorphism inwards Java which allows having multiple constructors amongst a unlike advert inwards i Class inwards java.

Why do yous overload Constructor inwards Java ?

JDK or Spring you must lead hold seen a lot of method overloading together with constructor overloading. Constructor overloading makes sense if yous tin dismiss Construct object via a unlike way. 

One of Classical illustration of Constructor overloading is ArrayList inwards Java. ArrayList has 3 constructors i is empty, other takes a collection object together with i takes initial Capacity. these overloaded constructors allow flexibility land creating an ArrayList object. It may survive possible that you don't know the size of ArrayList during creation together with then yous tin dismiss exactly purpose default no declaration constructor but if you know size together with then its best to purpose overloaded Constructor which takes capacity. 

Since ArrayList tin dismiss likewise be created from roughly other Collection, may survive from roughly other List than having roughly other overloaded constructor makes lot of sense. By using overloaded constructor yous tin dismiss convert your ArrayList into Set or whatever other collection.

Constructor overloading inwards Java Example

How to overload Constructor inwards Java

Constructor overloading is non complex yous exactly involve to create roughly other constructor, apparently same advert equally of class but unlike signature but in that place are for certain rules related to Constructor overloading which needs to be remembered land overloading constructor inwards Java. e.g. One Constructor tin dismiss solely survive called from within of roughly other Constructor together with if called it must survive the outset declaration of that Constructor. hither is an illustration of right together with wrong constructor overloading:

public loan(){

  this("");  //correct

}

public loan(){

  System.out.println("Calling overloaded Constructor inwards Java");

  this("");  //incorrect - throw compilation error.

}

public loan(String type){

  this.loanType= type;

}

Also, in i trial yous render constructor on Class inwards Java , Compiler volition non insert or add together default no declaration constructor , therefore brand for certain yous add together a default constructor inwards your class. Other rules of method overloading

also apply on Constructor overloading inwards Java e.g. Number or type of arguments of constructor should survive different. Just changing access modifier of Constructor volition non trial inwards overloading instead it will throw compilation fault equally shown inwards below example:

public loan(String type){

  this.loanType= type;

}

//compilation fault - solely access modifier is changed

private loan(String type){

  this.loanType= type;

}

Important points related to Constructor overloading:

1. Constructor overloading is similar to method overloading inwards Java.

2. You tin dismiss telephone telephone overloaded constructor past times using this() keyword inwards Java.

3. overloaded constructor must survive called from roughly other constructor only.

4. brand for certain yous add together no declaration default constructor because in i trial compiler volition non add together if yous lead hold added any constructor inwards Java.

5. if an overloaded constructor called , it must survive the outset declaration of constructor inwards java.

6. Its best do to lead hold i primary constructor together with allow overloaded constructor calls that. this way

your initialization code volition survive centralized together with easier to seek out together with maintain.

That’s all on Constructor overloading inwards java. The biggest wages of Constructor overloading is flexibility which allows yous to create the object inwards a unlike agency together with classic examples are diverse Collection classes. Though yous should retrieve that in i trial yous add together a constructor, a compiler volition non add together default no declaration constructor.

Thanks

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