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Exploring Constructor Overloading in Java

When it comes to object-oriented programming languages such as Java, constructors are regarded as one of the fundamental building blocks. 

 

In object-oriented programming languages like Java, constructors are regarded as one of the fundamental building blocks. In Java, class objects are initialized using constructors. A constructor initializes the function and additional state data when it is called. Check out our Full Stack Developer Course for more in depth knowledge.

 

In Java, constructors are subject to overloading, just like methods are. Constructor overloading in Java is covered in this article, along with how it differs from method overloading.

 

Table of Content

 

Constructor Overloading in Java

Exploring Constructor Overloading in Java

 

Constructor overloading in Java is a technology that enables the definition of numerous constructors with various parameter lists in a class. 

 

Constructor overloading is comparable to method overloading, which enables the definition of numerous methods in a class with the exact same name but distinct parameters. Instead of needing to design distinct classes, programmers may develop objects with various initial states by utilizing constructor overloading.

 

By designing constructors with several argument lists, constructor overloading can be accomplished. The quantity, kind, and order of the parameters can vary amongst parameter lists. An object is initialized after being created by calling the constructor with the proper parameter list.

When Do We Need Constructor Overloading in Java?

An object may need to be initialized in a variety of ways at times. Constructor overloading can be used to do this. The Thread class, for instance, offers 8 different sorts of constructors. 

 

Let’s say we don’t want to define any parameters for a thread. In such a scenario, we can just utilize the Thread class’s default constructor. 

 

Thread t= new Thread (” MyThread “

Brief Comparison with Method Overloading

  • The user actively calls methods, whereas constructors are notified automatically whenever an object is formed.
  • While the method name shouldn’t be identical to the class name, the constructor must have the identical title as the class.
  • There is no return type for constructors, but there is one for methods, which can be either void or an object type.
  • Although a method can carry out some class-specific tasks, a constructor is utilized to initialize an object.

Syntax and Structure of Constructors in Java

Here is the syntax of Java constructor overloading: 

 

class ClassName {
   ClassName() {
   }
}

However, constructor overloading in Java is of two types: 

 

  • Parameterized constructors 
  • No argument constructors

Also, when creating the structure of constructor overloading in Java, make sure: 

 

  • The Java constructor doesn’t have a return type
  • The name of the constructor overloading in Java must be the same as the class
  • The Java compiler automatically creates a constructor when it is not specifically defined. 

Examples Using Constructor Overloading in Java

Here is a constructor overloading in Java example with code and a brief description: 

 

Constructor Overloading in Java Example: Developing a class with numerous constructors that take different parameters

 

Code: 

class Person {
   private String name;
   private int age;
 
   // Default constructor
   public Person() {
       name = "";
       age = 0;
   }
 
   // Constructor that takes a name parameter
   public Person(String name) {
       this.name = name;
       age = 0;
   }
 
   // Constructor that takes both name and age parameters
   public Person(String name, int age) {
       this.name = name;
       this.age = age;
   }
   public String toString(){
       return name + " " + age;
   }
}
class PrepBytes{
   public static void main(String args[]){
       Person p1 = new Person();
       Person p2 = new Person("Amigo");
       Person p3 = new Person("Amigo", 18);
       System.out.println(p1.toString());
       System.out.println(p2.toString());
       System.out.println(p3.toString());
   }
}

Output:
0
Amigo 0
Amigo 18

Description:

 

Three Java constructor overloading’s were deployed to generate the Person class in this example. The first constructor here is the default constructor, where the name and age fields are initialized to empty strings and zero, respectively. 

 

The second constructor accepts a name parameter and sets the age field to 0 while initializing the name field to the parameters’ value. 

 

The third constructor sets up both variables to the appropriate values and accepts two parameters: name and age. The toString method has also been modified so that the console screen can display the objects’ elements.

Pros and Cons of Using Constructor Overloading with Different Parameters

The use of constructor overloading in Java has its own set of pros and cons. Let’s learn what they are: 

 

Pros Cons
  • Enables Initialization of Objects: Programmers specify the number of constructors with various parameter lists to initialize objects with various initial states without needing to build distinct classes.
  • Improves Code Readability: By using constructor overloading in Java, programmers can offer meaning names to constructors, which can further improve code readability while making the code simpler to understand. 
  • Lowers Code Redundancy: By offering numerous Java constructors with distinct argument lists, programmers can prevent replicating code in various areas of the class.
  • Ambiguity: The Java constructor Overloading can become subject to ambiguity if it doesn’t leverage different numbers or types of arguments. 
  • Compiler Issue: Even though the input variables have distinct names, the Java compiler won’t be able to tell one method from another if you write two identical methods that take two distinct values as parameters in the same class.

Constructor Chaining

Exploring Constructor Overloading in Java

Constructor chaining is the act of executing one constructor from another of the same class. Constructor chaining’s major benefit is that it allows you to send parameters via a variety of constructors while handling initialization only once. 

 

By giving the user several constructors, you may preserve your initializations in one place. Imagine that we don’t chain and that two distinct constructors each require a certain parameter. 

 

If so, you will need to initialize the parameter in question twice. If the initialization modifications, you will need to alter it in each constructor rather than just the first. Also read about Inheritance in Java – A Complete Guide by Hero Vired.

 

How to Use Constructor Chaining to Call One Constructor from Another

 

In a single class, you can define numerous constructors, every single of which can accept a different amount of arguments. To make use of constructor overloading in Java, use the keyword this() to invoke any of the constructors into the other (of the same class) constructor.

 

Embedding parameters in this()’s round brackets indicate that the constructor you invoke accepts them. You must keep in mind that the initial line of the calling constructor must always be called when calling a constructor with this(). Additionally, at least one Java constructor overloading must not employ this() statement.

Difference Between Constructor Overloading in Java and Method Overloading In Java

Here is a table showing the difference between Constructor Overloading in Java and Method Overloading: 

 

Method Overloading Java Constructor Overloading
  • In Java, a method is a regular function that may be invoked on a class or an object.
  • Methods can accept many arguments and are specifically invoked by name.
  • The return type of a method can vary depending on the overloaded method.
  • A class may have numerous methods with the exact same name but distinct argument lists thanks to method overloading. 
  • When an object is formed in Java, a special method called a constructor is invoked.
  • When an object is generated, its constructors are perpetually invoked.
  • There is no return type in Java constructor overloading
  • A class can have many constructors with various argument lists thanks to constructor overloading in Java.

Conclusion

With this, we conclude this comprehensive guide on constructor overloading in Java. If you’re looking forward to learning more about Java constructor overloading, enrolling in a professional course or reading online resources would be a great way to start. 

 

For instance, check out this blog on ‘Mastering Constructors in Java: Types and Examples’ to gain more advanced insight into this subject matter. The full-stack development course at Hero Vired can give you the professional knowledge, skill, expertise, exposure, as well as validation you seek as a Java expert. 

 

However, until you decide to enroll yourself, keep reading our blogs to upscale your knowledge constantly. Check out blogs like ‘ternary operator in Java’ and more to gain as much insight into Java as possible.

 

FAQ's

The usage of many constructors in an instance class is known as constructor overloading in Java. However, the signatures of every overloaded constructor must be unique. Each constructor needs a unique list of parameters for the compilation to succeed.
  • The constructor’s name and the class name must coincide and match.
  • A return type cannot exist in a constructor.
  • The phrases synchronized, final, abstract, and static are not allowed in Java constructor.
These are things to bear in mind when writing constructors because breaking them will cause compilation issues.
Here are the following advantages of using Java constructor overloading while writing Java programs:
  • Each overloaded constructor performs a variety of tasks for particular goals.
  • It makes it simpler to define a class's several constructors, each with a unique signature.
  • There are many ways to initialize class instances using constructor overloading.
  • Constructor overloading makes it feasible for static polymorphism.

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