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What is the best way to filter a Java Collection?

I want to filter a java.util.Collection based on a predicate.

Simplest (but not most readable) way is to iterate it and use Iterator.remove() method:

Iterator<Foo> it = col.iterator();
while( it.hasNext() ) {
  Foo foo = it.next();
  if( !condition(foo) ) it.remove();

Now, to make it more readable, you can wrap it into a utility method. Then invent a IPredicate interface, create an anonymous implementation of that interface and do something like:

  new IPredicate<Foo>(){
    public boolean keepIt(Foo foo) {
      return foo.isBar();

where filterInPlace() iterate the collection and calls Predicate.keepIt() to learn if the instance to be kept in the collection.

I don't really see a justification for bringing in a third-party library just for this task.

Answer is