public class Main {
private final int value = 3;
public static Runnable buildRunner() {
return new Runnable() {
@Override
public void run() {
System.out.println(Main.this.value);
}
};
}
}
I am using Eclipse Kepler, with JRE 7.
In the buildRunner method - why I am able to see the this of Main? What is the 'this' of Main in a static method? Why does this compile?
I can only do that if value is final. I cannot call instance methods of Main and stuff, but value is not decalred static! Furthermore, if I want to use in the buildRunner method, outside the run method of the new Runnable, the compiler stops me from doing that.
JLS § 15.8.4 says "The value of an expression of the form TypeName.this is the n'th lexically enclosing instance of this". Since there is no enclosing instance of Main in your example, the code is not valid.
In javac, the code produces the error "non-static variable this cannot be referenced from a static context". The fact that it compiles in Eclipse appears to be an obscure bug in Eclipse (which has its own compiler).
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