Type conversion (JDK1.5 Autoboxing/Unboxing) : Autobox Unbox « Data Type « Java Tutorial

public class Main {
  public static void main(String... args) {
    Integer integer = 1; // int into Integer

    int i = integer + 3; // mix Integer and ints


2.18.Autobox Unbox
2.18.1.Type conversion (JDK1.5 Autoboxing/Unboxing)
2.18.2.Boxing and Unboxing
2.18.3.Autoboxing and Auto-Unboxing
2.18.4.Manually boxes the value 100 into an Integer
2.18.5.The modern way to construct an Integer object that has the value 100
2.18.6.To unbox an object
2.18.7.Autoboxing/unboxing: an argument passed to a method or returned from a method
2.18.8.Autoboxing/unboxing occurs inside expressions
2.18.9.Auto-unboxing: mix different types of numeric objects in an expression.
2.18.10.Using an integer object to control a switch statement
2.18.11.Autoboxing/Unboxing Boolean and Character Values
2.18.12.Autoboxing/unboxing takes place with method parameters and return values.
2.18.13.Auto-unboxing allows you to mix different types of numeric objects in an expression.