Java™ How to Program, Seventh Edition

17.3. Autoboxing and Auto-Unboxing

Prior to Java SE 5, if you wanted to insert a primitive value into a data structure that could store only Objects, you had to create a new object of the corresponding type-wrapper class, then insert this object in the collection. Similarly, if you wanted to retrieve an object of a type-wrapper class from a collection and manipulate its primitive value, you had to invoke a method on the object to obtain its corresponding primitive-type value. For example, suppose you want to add an int to an array that stores only references to Integer objects. Prior to Java SE 5, you would be required to “wrap” an int value in an Integer object before adding the integer to the array and to “unwrap” the int value from the