Consider the following simple code:

public class Test {

      private final int arg;

      private final Runnable runnable1 = new Runnable() {

            @Override

            public void run() {

                 // No errors here, exactly as expected

                 System.out.println("ARG: " + arg);

            }

       };

       // Error: variable arg might not have been initialized

       private final Runnable runnable2 = () -> System.out.println("ARG: " + arg);

       public Test(int arg) {

              this.arg = arg;

       }

}

The java compiler (version 1.8.0-b132) produces the following error when compiling this code: "Error:(14, 46) java: variable arg might not have been initialized"

Actually, I do not expect the error here.

Both declarations 'runnable1' and 'runnable2' are essentially the same: these are just Runnable objects accessing value of the 'arg' field (which is initialized in the constructor).

The only difference between the declarations is that 'runnable1' - is an old-fashion instantiation of Runnable, whereas 'runnable2' - is an instantiation of Runnable via a lambda expression.

I expect them both to work the same.

Is my expectation wrong, or is this a bug in java compiler?

Any help will be appreciated.