Java 8 - converting an Integer to a long compilation issue

Question

I have the following abstract generic data holder in my project (simplified):

public abstract static class Value {

    E value;

    public void se         


        

Answer 1

A known Eclipse bug: https://bugs.eclipse.org/bugs/show_bug.cgi?id=440019

Fixed in Eclipse 4.5 M3.

Answer 2

According to the JLS for Java 8 this should not happen:

5.1.2. Widening Primitive Conversion

19 specific conversions on primitive types are called the widening primitive conversions:

[..]

• int to long, float, or double

[..]

5.1.8. Unboxing Conversion

[..]

• From type Integer to type int

What should happen is an unboxing from Integer to int, and then a widening conversion to long. This is actually happening as expected in Oracle JDK (1.8.0.25).

I believe you came across a compiler bug into your JDK. You should probably try an updated version or file a bug with the maintainers.