Why doesn't java.util.HashSet have a get(Object o) method?

Question

I\'ve seen other questions about getting objects from Set\'s based on index value and I understand why that is not possible. But I haven\'t been able to find a

Answer 1

As everyone mentioned before, there is no such method and for good reasons. That being said, if you wish to get a certain object from a HashSet in java 8 using a one-liner (almost), simply use streams. In your case, it would be something like:

Foo existing = set.stream().filter(o -> o.equals(new Foo("1"))).collect(Collectors.toList()).iterator().next();

Note that an exception will be thrown if the element doesn't exist so it is technically not a one-liner, though if the filter is properly implemented it should be faster than a traditional iteration over the collection elements.