Java How to Program, Early Objects, 11th Edition

16.4 Autoboxing and Auto-Unboxing

Java provides boxing and unboxing conversions that automatically convert between primitive-type values and type-wrapper objects. A boxing conversion converts a value of a primitive type to an object of the corresponding type-wrapper class. An unboxing conversion converts an object of a type-wrapper class to a value of the corresponding primitive type. These conversions—called autoboxing and auto-unboxing—are performed automatically. Consider the following statements:

Integer[] integerArray = new Integer[5]; // create integerArray
integerArray[0] = 10; // assign Integer 10 to integerArray[0]
int value = integerArray[0]; // get int value of Integer

In this case, autoboxing occurs when assigning an int value ( ...