Is final used for optimization in C++? It can be, and is. As noted, it is being used already; see here and here showing the generated code for the override with and without final. An optimisation along these lines would relate to the “de-virtualization” of the virtual calls. This is not always immediately affected by … Read more
In the JLS, §8.3.3. Forward References During Field Initialization, its stated that there’s a compile-time error when: Use of instance variables whose declarations appear textually after the use is sometimes restricted, even though these instance variables are in scope. Specifically, it is a compile-time error if all of the following are true: The declaration of … Read more
No, at the time of this writing there is not. There is a proposal for such a keyword which is still being considered, but may or may not ever be implemented. See: github.com/Microsoft/TypeScript/issues/9264, and github.com/Microsoft/TypeScript/issues/8306
Answering each of your points in turn: primitive variables: can be set only once. (memory and performance gain) Yes, but no memory gain, and no performance gain. (Your supposed performance gain comes from setting only once … not from final.) objects variables: may be modified, final applies to object reference. Yes. (However, this description miss … Read more
(1) Static methods cannot be overridden, they can however be hidden using the ‘new’ keyword. Mostly overriding methods means you reference a base type and want to call a derived method. Since static’s are part of the type and aren’t subject to vtable lookups that doesn’t make sense. E.g. statics cannot do: public class Foo … Read more
The closest thing (not exactly the same, final has other meanings too) for Java final fields I can think of is readonly: public static readonly MyClass field = new MyClass(“foo”); If you have a primitive type (string, int, boolean), you may want to use const instead. public const string MAGIC_STRING = “Foo”;
There are two main reasons you might want to mark an argument final. First, if you’re planning on using the argument in an anonymous inner class, then you must mark it final so that it can be referenced in that class. This is actually a pretty common use case for marking arguments final. The other … Read more
You should try to do this, whenever it is appropriate. Besides serving to warn you when you “accidentally” try to modify a value, it provides information to the compiler that can lead to better optimization of the class file. This is one of the points in the book, “Hardcore Java” by Robert Simmons, Jr. In … Read more
JLS hunting: It is a compile-time error if a final variable is assigned to unless it is definitely unassigned (§16) immediately prior to the assignment. Quoth chapter 16: V is definitely unassigned before a catch block iff all of the following conditions hold: V is definitely unassigned after the try block. V is definitely unassigned … Read more
Imagine that shorthand looks a lot like this: for (Iterator<Integer> iter = listOfNumbers.iterator(); iter.hasNext(); ) { final int i = iter.next(); { System.out.println(i); } }