private static void badtamper(final ArrayList l) {
ArrayList nl = new ArrayList();
nl.add(”One”);
nl.add(”Two”);
nl.add(”Three”);
l = nl; – THIS IS COMPILATION TIME ERROR – you can’t change reference if it is final, but you can change data in object
System.out.println(”In bad callee value :” + l);
}

Ok i can change some things:

public static void main(String[] args) {
ArrayList l = new ArrayList();
l.add(”1?);
l.add(”2?);
l.add(”3?);
System.out.println(”Original List ” + l);
badtamper(l);
System.out.println(”In caller value after bad callee:” + l);
tamperlist(l);
System.out.println(”In caller value :” + l);
}

private static void badtamper(final ArrayList l) {
l.remove(2);
l.add(2, “bad”);
System.out.println(”In bad callee value :” + l);
}

private static void tamperlist(ArrayList> l) {
l.remove(2);
l.add(2, “not bad”);
System.out.println(”In callee value :” + l);
}

Now when the code is run the following gets printed out :
Original List [1, 2, 3]
In bad callee value :[1, 2, bad]
In caller value after bad callee:[1, 2, bad]
In callee value :[1, 2, not bad]
In caller value :[1, 2, not bad]

Actually no difference.

Using final to clutter up your code in an attempt to prevent lines like this is pure rubbish. If you are working for/with developers who make such rudimentary mistakes such as this I suggest you fire them or switch jobs.

If you really need a compiler to prevent you from making such mistakes you really have much bigger problems than finals. It’s absolutely pointless in java

Sometimes you run across some code that makes you cringe a little bit. That happened to me today when I ran across this blog post. It’s about how the final modifier is used for method parameters. A sample of what the post is trying to convey look…