Unboxing Long in java

Question

In some code I see this:

private void compute(Long a, Long b, Long c) {
        long result = a-(b+c);
...
         


        

Answer 1

As per the javadoc

Boxing conversion converts expressions of primitive 
type to corresponding expressions of reference type. 
Specifically, the following nine conversions are called the boxing conversions:

From type boolean to type Boolean

From type byte to type Byte

From type short to type Short

From type char to type Character

From type int to type Integer

From type long to type Long

From type float to type Float

From type double to type Double

From the null type to the null type


Ideally, boxing a given primitive value p, would always yield an identical reference.     
In practice, this may not be feasible using existing implementation techniques. The  
rules above are a pragmatic compromise. The final clause above requires that certain 
common values always be boxed into indistinguishable objects. The implementation may  
cache these, lazily or eagerly. For other values, this formulation disallows any 
assumptions about the identity of the boxed values on the programmer's part. This would 
allow (but not require) sharing of some or all of these references.

This ensures that in most common cases, the behavior will be the desired one, without     
imposing an undue performance penalty, especially on small devices. Less memory-limited 
implementations might, for example, cache all char and short values, as well as int and 
long values in the range of -32K to +32K.`

Here is the Oracle Doc source