Some small knowledge of Java encapsulation.

1, the type of packaging in the expression and at least one of the expression is not a wrapper type, so Long a = = 128L in a auto-unpacking degenerate to the basic type comparison, so the value is compared to true.
2, c = = (A + b), this should be noted, in the inclusion of arithmetic operations including (= =), will be automatic unpacking operation is completed and then boxed, in the Xx.equals () will automatically box and then compare is not XX type is not return false
3, Long integer cache is 128 to 127,cache inside the box when the return of the same address including equals when boxing.

Some small knowledge of Java encapsulation.