Four ways to traverse Map, four ways to traverse map

Four ways to traverse Map, four ways to traverse map

In Java programming, collection traversal is used all the time. Thanks for the following methods of Map traversal:

Public static void main (String [] args) {Map <String, String> map = new HashMap <String, String> (); map. put ("1", "value1"); map. put ("2", "value2"); map. put ("3", "value3"); // the first type is commonly used. The second value is System. out. println ("through Map. keySet traversal key and value: "); for (String key: map. keySet () {System. out. println ("key =" + key + "and value =" + map. get (key);} // second System. out. println ("through Map. entrySet uses iterator to Traverse key and value: "); Iterator <Map. entry <String, String> it = map. entrySet (). iterator (); while (it. hasNext () {Map. entry <String, String> entry = it. next (); System. out. println ("key =" + entry. getKey () + "and value =" + entry. getValue ();} // The third type is recommended, especially when the capacity is large. out. println ("through Map. entrySet traverses key and value "); for (Map. entry <String, String> entry: map. entrySet () {System. out. println ("key =" + entry. getKey () + "and value =" + entry. getValue ();} // The fourth System. out. println ("through Map. values () traverses all values, but cannot Traverse key "); for (String v: map. values () {System. out. println ("value =" + v );}}