Differences between list, set, and map

The list dynamic set interface can dynamically add elements. It is convenient to use the itractor iterator to traverse collection elements;
Map is a set of key-value pairs. The advantage is that you can find the corresponding value through the corresponding key, just like opening a lock with a key;
Set is also a set. The relationship between adjacent two elements is convenient to search for adjacent set elements horizontally;

 

The list iterative access will be displayed in the order you add (ADD! Hashset is the most common option for adding duplicate elements. duplicate elements cannot be added. During iterative output, the unordered map is not the same as the above two, it stores key-value pairs

 

List and set are under the collection interface, while map is also an interface. Although they are all sets, the underlying principle is quite different!