Ordered Set and unordered set

1. Ordered Set: Elements in the set can be accessed by key or index

. Unordered set: the elements in the set can only be traversed.

An ordered set has good performance in adding, deleting, and modifying attributes.

2.

Unordered set: Set

Ordered Set: List

Therefore, all implementations of the Set abstractset, copyonwritearrayset, enumset, hashset, jobstatereasons, linkedhashset, treeset

They are all unordered.

List

Abstractlist, abstractsequentiallist, arraylist, attributelist,
Copyonwritearraylist, rule list, rolelist, roleunresolvedlist, stack,
Vector
They are all ordered.

For supplement

MAP is stored based on the key.

Therefore, from this perspective, it is ordered.