In Java, "boxing" is the process of converting a primitive data type to its corresponding wrapper class object. Wrapper classes are provided in the java.lang package for each of the eight primitive data types. Boxing is performed automatically by the Java compiler through a process called "autoboxing", which occurs when a primitive value is assigned to a variable of its corresponding wrapper class or passed as an argument to a method that expects an object of the wrapper class.
In this example, autoboxing is demonstrated by assigning an int value to an Integer variable, which automatically converts the int value to an Integer object. Additionally, autoboxing is used with an ArrayList of Integer objects, where int values are automatically converted to Integer objects when added to the list.