Rules for overloading methods using widening, boxing, and var-args : Boxing Unboxing « Utility Classes « SCJP

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SCJP » Utility Classes » Boxing Unboxing

8.10.1.Rules for overloading methods using widening, boxing, and var-args

Primitive widening uses the "smallest" method argument possible.



Used individually, boxing and var-args are compatible with overloading.



You CANNOT widen from one wrapper type to another. (IS-A fails.)



You CANNOT widen and then box. (An int can't become a Long.)



You can box and then widen. (An int can become an Object, via Integer.)



You can combine var-args with either widening or boxing.

8.10.Boxing Unboxing
	8.10.1.	Rules for overloading methods using widening, boxing, and var-args
	8.10.2.	Boxing, ==, and equals()
	8.10.3.	Where Boxing Can Be Used
	8.10.4.	Wrapper reference variables can be null
	8.10.5.	Overloading Method Matching
	8.10.6.	Overloading with Boxing and Var-args
	8.10.7.	Predict the output of the following
	8.10.8.	boxing beat var-args
	8.10.9.	Overloading When Combining Widening and Boxing
	8.10.10.	A boxing operation followed by a widening operation in order to match an invocation to a method.
	8.10.11.	Overloading in Combination with Var-args
	8.10.12.	Autoboxing and auto-unboxing are compiler modifications that permit previously illegal combinations of wrappers and primitives.
	8.10.13.	The wrapper on the left-hand side must correspond exactly to the primitive type on the right-hand side.
	8.10.14.	The following autoboxing assignment is illegal
	8.10.15.	Boxing requires an exact match between the wrapper class and the primitive type.
	8.10.16.	Boxing also occurs when a method's return type is a wrapper.
	8.10.17.	Unboxing is the automatic extraction of a wrapped value.
	8.10.18.	Unboxing the parameter

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