Eclipse null analysis: The expression of type int needs unchecked conversion to conform to '@Nonnull Integer'

问题

When configuring Eclipse 4.2.0 to perform a null analysis (configured to use @javax.annotation.Nonnull etc.), the following code will generate the warning

Null type safety: The expression of type int needs unchecked conversion to conform to '@Nonnull Integer'

class C
{
  static void foo(int i)
  {
    bar(i); // Warning
  }

  static void bar(@javax.annotation.Nonnull Integer i)
  {
  }
}

How am I supposed to fix this (without using @SuppressWarnings("null"))? It seems that the analyzer does not know that boxed primitives cannot be null.

回答1:

I think it's a bug in Eclipse. I tried the same with IntelliJ, and it works as expected there.

When I pass a Null, IntelliJ correctly tells me that nulls are not allowed.

However, when I use the normal i variable, no error pops ups up, which is quite correct.

I even tried this, just for the experiment, so I'm not sure if you're stuck to Eclipse, else I'd recommend using either the free Community version of IntelliJ, or the Ultimate edition.

来源：https://stackoverflow.com/questions/16241983/eclipse-null-analysis-the-expression-of-type-int-needs-unchecked-conversion-to