A final counter in a for loop?

Question

I have this code:

    List r = new ArrayList<>();
    for(int i = 0; i < 10; i++) {
        r.add(new Runnable() {

            @Ove         


        

Answer 1

I think your solution is the simplest way.

Another option would be to refactor the creation of the inner class into a factory function that does it for you, then your loop itself could be something clean like:

List r = new ArrayList<>();
for(int i = 0; i < 10; i++) {
    r.add(generateRunnablePrinter(i));
}

And the factory function could just declare a final parameter:

private Runnable generateRunnablePrinter(final int value) {
    return new Runnable() {
       public void run() {
           System.out.println(value);
       }
    };
}

I prefer this refactored approach because it keeps the code cleaner, is relatively self descriptive and also hides away all the inner class plumbing.

Random digression: if you consider anonymous inner classes to be equivalent to closures, then generateRunnablePrinter is effectively a higher order function. Who said you can't do functional programming in Java :-)