Sequence of map implementation classes

Map The implementation classes of are ：LinkedHashMap,TreeMap,HashMap

LinkedHashMap： Record the order of adding order . Inherited from HashMap, Than HashMap Added double linked list , The front and back pointers are added to the node ,LinkedHashMap Added in head,tail The pointer

TreeMap： Default ascending order , Red and black trees

HashMap： disorder , Array + Linked list + Red and black trees

// LinkedHashMap Output the results in the order of insertion 
Map<Character,Integer> map = new LinkedHashMap<>();
map.put('c',2);
map.put('a',4);
map.put('g',3);
map.put('d',1);
// {c=2, a=4, g=3, d=1}

// TreeMap according to key Output results in sequence 
Map<Character,Integer> map = new TreeMap<>();
map.put('c',2);
map.put('a',4);
map.put('g',3);
map.put('d',1);
// {a=4, c=2, d=1, g=3}

// HashMap  disorder 
Map<Character,Integer> map = new HashMap<>();
map.put('c',2);
map.put('a',4);
map.put('g',3);
map.put('d',1);
// {a=4, c=2, d=1, g=3}