Java

Autoboxing and Autounboxing

Bil Al

Dec 30, 2022 • 2 min read

Autoboxing is a feature of the Java programming language that allows you to use primitive values as if they were objects.

In Java, each primitive type has a corresponding wrapper class that allows you to use primitive values as objects. For example, the int primitive type has a corresponding Integer wrapper class, the boolean primitive type has a corresponding Boolean wrapper class, and so on.

Autoboxing allows you to use primitive values in contexts where only objects are allowed, without having to explicitly wrap them in their corresponding wrapper class.

Here's an example of how you can use autoboxing in Java:

List<Integer> list = new ArrayList<>();

// Without autoboxing
list.add(new Integer(100));

// With autoboxing
list.add(100); // equivalent to list.add(new Integer(100));

Autoboxing is implemented by the Java compiler, which automatically inserts the necessary code to wrap and unwrap primitive values as needed. This allows you to use primitive values in a more natural and convenient way, without having to worry about the details of wrapping and unwrapping them.

It's important to note that autoboxing can have a performance impact, as it involves additional memory allocation and method calls. In cases where performance is critical, you may want to consider using primitive values directly, rather than relying on autoboxing.

Autounboxing is the reverse process of autoboxing. It is a feature of the Java programming language that allows you to use objects of wrapper classes as if they were primitive values.

Autounboxing allows you to use objects of wrapper classes in contexts where only primitive values are allowed, without having to explicitly unwrap them.

Here's an example of how you can use autounboxing in Java:

List<Integer> list = new ArrayList<>();
list.add(100);

// Without autounboxing
int i = list.get(0).intValue();

// With autounboxing
int i = list.get(0); // equivalent to int i = list.get(0).intValue();

Autounboxing is implemented by the Java compiler, which automatically inserts the necessary code to unwrap objects as needed. This allows you to use wrapper objects in a more natural and convenient way, without having to worry about the details of unwrapping them.

It's important to note that autounboxing can have a performance impact, as it involves additional method calls. In cases where performance is critical, you may want to consider using wrapper objects directly, rather than relying on autounboxing.