Map and set Traversal (EntrySet method, supplementing enumeration and iterator)

 public  void   Mearge (map map) {map Returnmap  = new  Ha        Shmap<> ();  //  convert to Entry  set<map.entry        <object, object>> entries = Map.entryset ();  //  traverse  for  (map.entry<object, Object> Entry:entries) {Object key = Entry.getkey ();            Object val  = Entry.getvalue ();        System.out.println ( "key:value#" +key+ ":" +val "); }    }

The main use of the Map.entryset () method; Entry can be understood as a single key-value pair.

This also skips the process of set conversion to iterator and then traversal. Use foreach directly, in a concise manner.

Add a bit of knowledge about enumeration and iterator, before you see a blog post that says, use enumeration sparingly and use iterator more.

Enumeration interface main implementation of the two methods:

boolean	hasMoreElements()Tests If this enumeration contains more elements.
E	nextElement()Returns the next element of this enumeration if this enumeration object have at least one more element to provide.

boolean hasmoreelemerts (): Tests whether the enumeration enumeration object also contains elements, and if true, indicates that there are at least one element.
· Object Nextelement (): If the Bnumeration enumeration object also contains elements, the method gets the next element in the object.

Iterator interface Main method:

boolean	hasNext()Returns true If the iteration have more elements.
E	next()Returns the next element in the iteration.
void	remove()Removes from the underlying collection The last element of returned by this iterator (optional operation).

As can be seen above, iterator more than enumeration a deletion method, the other two methods function is similar, so it is recommended to use the iterator interface.

Map and set Traversal (EntrySet method, supplementing enumeration and iterator)