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

Java Map/Collection Cheat Sheet

Will it contain key/value pair or values only?

1) If it contains pairs, the choice is a map. Is order important?

. 1-1) If yes, follow insertion order or sort by keys?

. . 1-1-1) If ordered, LinkedHashMap

. . 1-1-2) If sorted, TreeMap

. 1-2) If order is not important, HashMap

2) If it stores only values, the choice is a collection. Will it contain duplicates?

. 2-1) If yes, ArrayList

. 2-2) If it will not contain duplicates, is primary task searching for elements (contains/remove)?

. . 2-2-1) If no, ArrayList

. . 2-2-2) If yes, is order important?

. . . 2-2-2-1) If order is not important, HashSet

. . . 2-2-2-2) If yes, follow insertion order or sort by values?

. . . . 2-2-2-2-1) if ordered, LinkedHashSet

. . . . 2-2-2-2-2) if sorted, TreeSet