Updated March 28, 2023
Introduction to Autoboxing in Java
Autoboxing is a process followed in JAVA wherein the conversion of primitive data is converted into the object type by the compiler. So, for example, if the variable is declared as “int,” then the variable is converted into object data type from primitive integer by the compiler, which is used in that format. There is one more process which is the reversal of autoboxing which is called “unboxing.”
Definition: Conversion of any value of primitive data type into an object of a respective wrapper class is called autoboxing.
Syntax
The syntax used for autoboxing is as follows-
primitive_DataType variableName = 'VariableValue';How does Autoboxing work in Java?
JAVA compiler takes the primitive data type and converts it into an object of the wrapper class. Then, the compiler works only if the below two points are satisfied:
- Variables are passed as a parameter to the function, which would expect object creation of wrapper class.
- Primitive values are assigned to variables so that the compiler can perform autoboxing.
- All the primitive data types are linked to their respective wrapper class (This is already done by JAVA stored in their libraries). The primitive data types and their linked wrapper classes are linked as:
| Primitive data type | Wrapper class |
| boolean | Boolean |
| byte | Byte |
| long | Long |
| double | Double |
| short | Short |
| char | Character |
| Int | Integer |
| float | Float |
Examples of Autoboxing in Java
Below are the examples of autoboxing in JAVA which are helpful to understand this concept further.
Example #1
Code:
import java.io.*;
class example1
{
public static void main (String[] args)
{
//here we are creating an integer "test1" having value of "100".
Integer test1 = new Integer(100);
System.out.println("Here is the value of integer test1 which is created into object of the wrapper class integer: " + test1);
//here we are autoboxing a character "test2" with a value of "a".
Character test2 = 'a';
System.out.println("Here is the value of test2 variable after autoboxing using character wrapper class: " + test2);
}
}Output:
Explanation:
The JAVA library named “java.io” was imported so that JAVA prime functionalities can be used. First, the main class name “example1” was created containing the main function. The main function is the point where the execution of the program will start. Next, an integer named “test1” was created and assigned with the value. It is slightly different from the normal way of declaring and assigning the values; as you can see, the wrapper class “Integer” was instantiated, and the value to be assigned is passed as a parameter to the wrapper class. This process is called objectifying the primitive data type using the wrapper class. No doubt that “JAVA” is called a fully object-oriented language.
In the next section of code, the Character primitive data type is assigned to a variable named “test2” with a value “a.” This is a usual way of declaring and assigning the variable with the value. This is working because the JAVA compiler is smart enough to convert the primitive data type into an object of its wrapper class automatically in the back. This functionality is called autoboxing in JAVA.
Example #2
Code:
public class BoxingWidening
{
// The function below is demonstrating the boxing functionality in JAVA.
static void testFunction(char i)
{
System.out.println("Program output for boxing:: ");
System.out.println("char in short");
}
// This function is demonstrating the widening functionality in JAVA.
static void testFunction(Character i)
{
System.out.println("Program output for widening: ");
System.out.println("Character in full");
}
public static void main(String args[])
{
char ch='a';
testFunction(ch);
}
}Output:
Explanation:
In this example, the difference between “widening” and “boxing” is demonstrated. Widening is a functionality where the full class name is used, for example, Integer or character instead of int or char. Two functions are defined with the same name, “testFunction,” one with widening and the other with boxing syntax declarations and assignments. In the main function, a character named “ch” is declared and assigned with a value “a,” and a function is called with its function name. This function has two definitions on its name. Since JAVA prefers boxing, the function’s boxing definition is called, and the parameter “ch” is passed to the boxing definition. The final result is displayed using the print() function. This function shows boxing definition in the output screen rather than taking a widening definition. Certainly, autoboxing is much powerful in comparison to the widening functionality offered by the JAVA language.
Advantages
Some of the advantages derived from this useful functionality by JAVA are enlisted below:
- The developer has to write less code, and this reduces the burden on the coder so that the coder can concentrate on complex logic.
- Cleaner code as the complexity of creating an object and instantiating it is abstracted due to compiler intelligence.
- The best strategy for information is picked up by the compiler using this. For example, if we want the value of the integer to be picked up, then we should use code: valueOf (int) rather than new Integer (int). This improves turnaround time.
- Promotes abstraction.
- Reduces the possibility of bugs in the lengthy code/ project because of abstraction.
Conclusion
Autoboxing is one of the best strategies to abstract complex code from the developer by adding compiler intelligence. This reduces the overhead on the developer of writing small code snippets which are not logically related. This is used so extensively by developers that the instantiating of a wrapper class is not known to many developers. Autoboxing is certainly a powerful and cleaner way of declaring and assigning the values to the variables.
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This is a guide to Autoboxing in Java. Here we discuss How does Autoboxing work in Java and Examples along with codes and outputs. You may also have a look at the following articles to learn more –
