HashMap&&TreeMap&&HashTable

/*

• HashMap -> thread safe

• The bottom layer is achieved by the hash table

• hashmap deduplication -> The key to the weight data from the reference data types defined: hashCode () and equals ()

• Hashtable and HashMap similar -> thread-safe

• TreeMap

• The bottom layer is implemented by a red-black tree

• TreeMap deduplication -> The key to the weight, the custom data reference data types: internal | external comparator

• Select: If you want to do some sort of rule based on key selection TreeMap, or select HashMap
  * /
  public class HashMapDemo {
  public static void main (String [] args) {
  // HashMap <the Person, Boolean> = the Map new new HashMap () ;

  TreeMap<Person, Boolean> map=new TreeMap((o1,o2)->((Person)o2).getAge()-((Person)o1).getAge());
  map.put(new Person("饶瑞",22),true);
  map.put(new Person("林源",24),false);
  map.put(new Person("韩龙",23),true);
  map.put(new Person("徐敏生",20),false);
  map.put(new Person("林源2",24),true);
  System.out.println(map);
  

  }
  }