Accessing final instance variables inside constructur before initialized

[Alex Buckley]

javac is correctly implementing the JLS 16.9 specification:

"If C [here, SubClass] has no instance initializers or instance variable 
initializers, then V [here, test] is not definitely assigned (and 
moreover is definitely unassigned) after an explicit or implicit 
superclass constructor invocation."

Alex

On 2/13/2015 3:31 AM, Tom Schindl wrote:
> Hi,
>
> I came across some code which compiles and works fine (at runtime) with
> the Eclipse Java Compiler but fails with javac (8u40).
>
> I've stripped it down to this (the original code used lambda expression
> accessing the instance field).
>
>>
>> public abstract class CompilerTest {
>>
>> 	public CompilerTest() {
>> 		System.err.println("Constructor Base: " + getTest());
>> 	}
>>
>> 	protected abstract String getTest();
>>
>> 	static class SubClass extends CompilerTest {
>> 		private final String test;
>>
>> 		public SubClass(String test) {
>> 			System.err.println(this.test); // javac fails
>> 			this.test = test;
>> 			System.err.println(this.test);
>> 		}
>>
>> 		@Override
>> 		protected String getTest() {
>> 			return this.test;
>> 		}
>>
>> 	}
>>
>> 	public static void main(String[] args) {
>> 		new SubClass("Hello World!");
>> 	}
>> }
>
> So javac fails with
>
>> CompilerTest.java:14: error: variable test might not have been initialized
>> 			System.err.println(this.test);
>
> One might argue that most likely the above code is a really not what the
> user idented to do but I'm still not sure javac is correct in refusing
> to compile this piece of code.
>
> Tom
>