This is a favorite interview question. With this questions, the interviewer tries to find out how well you understand the behavior of objects with respect to constructors, methods, class variables (static variables) and instance variables. import java.util.ArrayList; import java.util.List; class Test { private final List foo; public Test() { foo = new ArrayList(); foo.add(“foo”); // … Read more
… starting in Java SE 8, a local class can access local variables and parameters of the enclosing block that are final or effectively final. A variable or parameter whose value is never changed after it is initialized is effectively final. For example, suppose that the variable numberLength is not declared final, and you add … Read more
Assuming no SecurityManager is preventing you from doing this, you can use setAccessible to get around private and resetting the modifier to get rid of final, and actually modify a private static final field. Here’s an example: import java.lang.reflect.*; public class EverythingIsTrue { static void setFinalStatic(Field field, Object newValue) throws Exception { field.setAccessible(true); Field modifiersField … Read more
Java doesn’t support true closures, even though using an anonymous class like you are using here (new TimerTask() { … }) looks like a kind of closure. edit – See the comments below – the following is not a correct explanation, as KeeperOfTheSoul points out. This is why it doesn’t work: The variables lastPrice and … Read more
If your fields are final, they must be set either on declaration or in the constructor. Once set, the compiler will throw an error when set again, because final variables are not allowed to be re-assigned.