Autoboxing and Unboxing in Java – AutoboxingAutoboxing refers to the automatic conversion of a primitive type variable to its corresponding. Since JDK version 5, Java provides two features, called autoboxing and auto- unboxing. They typically mean automatic conversion between. Java introduced a special feature of auto conversion of primitive types to the corresponding Wrapper class and vice versa. Autoboxing: Automatic.

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It blends to the natural way of writing Java code to the extent of almost getting unnoticed.

Now, what happens with mixed types of values? Autoboxing and auto-unboxing not only offer a convenient way to write code but also allays the chance of incorporating unintended errors in the code.

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Autoboxing is the automatic conversion that the Java compiler makes between the jxva types and their corresponding object wrapper classes. Here is the simplest example of autoboxing: This idea can be exploited to the advantage of the programmer in a way where the seemingly simple looking primitive types are geared up with additional features.

A narrowing primitive conversion may lose information about the overall magnitude of a numeric value and also may lose precision and range. Post a comment Email Article Print Article. A widening primitive conversion does not lose information about the overall magnitude of a numeric value in the following cases, where the numeric value is preserved exactly.

This auto conversion occurs according to the need.

It encapsulates primitive type unhoxing within object. There is the ninth primitive, called voidand its corresponding wrapper class is Void. Because primitive types are the building blocks of Java code, there must be some convenient conversion techniques between primitives and wrappers.


The compiler does not generate an error because it creates an Integer object from i and adds the object to li. Converting an object of a wrapper type Integer to its corresponding primitive int value is called unboxing.

Autoboxing and Unboxing in Java

The fractional value resulted from the evaluation is lost because we are storing the value in an integer variable. Examples and practices described in this page don’t take advantage ln improvements introduced in later releases. It encapsulates primitive type boolean within object.

Here is a simple program to illustrate the size and range of each data type in Java. Also, any conversion, even an automatic one, always needs some extra processing. The following table lists the primitive types and their corresponding wrapper classes, which are used by the Java compiler for autoboxing and unboxing:.

The conversion is implicit. For example, the int value 10 and 20 is auto boxed into a reference type by the addNumbers method whereas the return value is actually a primitive type but again is converted before autobpxing into the result reference type. Im helps prevent errors, but may lead to unexpected results sometimes.

Autoboxing and Unboxing in Java

wnd Java is a statically xnd language. Autbooxing does not include all companies or all types of products available in the marketplace. Converting a primitive value an intfor example into an object of the corresponding wrapper class Integer is called autoboxing. Guess what, there actually is. Autoboxing is a process by which primitive type is automatically encapsulated boxed into its equivalent type wrapper Auto-Unboxing is a process by which the value of an object is automatically extracted from a type Wrapper class.


It seems it is a namesake wrapper class because the class contains no method of its own. The Java compiler applies unboxing when an object of a wrapper class is:. To handle such type of situations, Java provides type Wrappers which provide classes that encapsulate a primitive type within an object.

Autoboxing and Unboxing

The result is the wrong value is printed! Java uses primitive data types such as anr, double, float etc. Let’s see down the line. Similarly, other data types have their specific size and range of stored values. Rest assured the principles behind it are intriguing and worth knowing.

It is a reverse process of boxing. The technique of converting an expression of primitive type as an wutoboxing of a corresponding reference type is called boxing conversion. Thus, the compiler converts the previous code to the following at runtime:.

When we perform increment operation on Integer object, it is first unboxed, then incremented and then again reboxed into Integer type object. Hence must autobocing used with care. This means we unwrap it or unbox it into a primitive type. But what about the conversion between primitives to wrapper and vice versa.