Wrapper Classes in Java: What is it, Why do we need it?

Java works on the concepts of OOP – Object-Oriented Programming. Despite that, Java can not be considered as a complete object-oriented language. That is because Java works with eight primitive data types – byte, short, int, float, long, and double. These Java data types are not objects, which makes Java not wholly object-oriented. 

However, wrapper classes provide a good way around that limitation by converting primitive data types into objects. In that way, wrapper classes make the Java code completely object-oriented. 

This is one of the more important concepts to understand for everybody beginning with the Java programming language. Let’s help you with that through this article. First, we’ll look at wrapper classes in Java and why we need them and their advantages. By the end of the article, you’ll be in a position to work with wrapper classes without being confused! 

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Wrapper class in Java

Software developers often stumble upon situations that would require them to not work with primitive data types but with objects. To achieve this conversion of primitive data type to objects, Java provides programmers with the concept of the wrapper class. This class helps in conversion from primitive to object as well as from object to primitive data type. 

Creating a wrapper class automatically creates a new field where the primitive data types are stored. The object of the wrapper class then holds the primitive data type. This process of converting primitive data types into objects using wrapper classes is known as boxing. While working with wrapper classes, you need to pass the primitive data type’s value to the constructor of the wrapper class. 

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The six wrapper classes – byte, short, int, float, long, and double – are all subclasses of the number class, which is an abstract class. The remaining two wrapper classes – boolean and character – are subclasses of the object class. 

Here’s a quick summary of the wrapper class for different primitive data types, along with the constructor argument required to create the wrapper class:

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Why are wrapper classes in Java needed? 

Wrapper classes in Java are beneficial for situations where the program demands working with an object instead of a primitive data type. In that sense, wrapper classes help the Java program be 100% object-oriented. Apart from that, wrapper classes in Java are needed for the following reasons: 

• To bind the values of different primitive data types into objects. This helps in performing complex operations and working with collections like HashMap, ArrayList, etc. 
• To provide different utility functions that can be used with primitive data types. 
• Since primitive data types can’t be given a null value, but wrapper classes can, they also act as a workaround for assigning a null value to any primitive data type. 

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What are the advantages of using wrapper classes in Java?

Wrapper class in Java provides the following primary benefits: 

• They help the code be serialisable. This is because serialisation requires the conversion of objects into streams. If programmers want to serialise a primitive value, it must first be converted into objects using wrapper classes. 
• They help with synchronisation because multithreading synchronisation in Java requires objects. 
• Primitive data can benefit from various util classes of the Java.util package. 
• Working with collection frameworks becomes possible using wrapper classes. 
• Converting primitive data types into objects makes it possible to change the value inside the function using a call-by-value method. 
• Wrapper classes in Java ensure that the program is polymorphic. 

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Examples

1. Converting a primitive type to object

public class Example{  

   public static void main(String args[]){  

//Converting float primitive into Float object  

float n=10.10;  

Float obj=Float.valueOf(n);  

System.out.println(n+ ” “+ obj);  

   }

}

Output:

10.10 10.10

As the output shows, both the primitive data as well as the object hold the same value. So, you can access the same value using obj or n, whatever you prefer, according to the situation. 

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2. Converting object to primitive type

public class Example{  

   public static void main(String args[]){  

//Creating Wrapper object 

Float o= new Float(50.00);  

 

//Converting the object to primitive

float n= obj.floatValue();

System.out.println(n+ ” “+ o);  

   }

}

Output:

50.00 50.00

The float object has been converted back to the float primitive data type in the above example. Likewise, you can do a lot of conversion and manipulations using wrapper classes in Java. There are different functions that wrapper classes work with. That discussion is beyond the scope of this article, but we recommend you explore wrapper classes in-depth, along with the different functions you will need to work with when handling wrapper classes. 

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In Conclusion

Like wrapper classes, there are also many other essential concepts and ideas that you need to master to excel in software development. At upGrad, we have mentored various students around the globe and helped them start their careers in their desired field. Our personalised training sessions and expert-led case study discussions help students stay on top of all the concepts acquired. 

To help students kickstart their software development career, we present to you a 5-month online program created by experts and industry leaders – Job-Linked PG Certification in Software Engineering. Apart from teaching you all the nuances of the field, the program will also help you get placed with top companies. So check out this course and get yourself registered today!