1+ package com .udemy .dsapart1 .hashmaps ;
2+ import java .util .HashMap ;
3+ import java .util .Map ;
4+ import java .util .Map .Entry ;
5+ import java .util .Set ;
6+ 7+ /**
8+ *
9+ * This class act as driver code to start execution via main() for HashMap
10+ * examples.
11+ *
12+ */
13+ public class TestDriverFromHashMaps {
14+ 15+ public static void main (String [] args ) {
16+ Map hash1Map =new HashMap <>();
17+ hash1Map .put ("clr" ,"Value-AL" );
18+ hash1Map .put ("01" ,"IBM" );
19+ hash1Map .put (null ,500 );
20+ hash1Map .put (2 ,"(*(#*($*" );
21+ hash1Map .put (3.99 ,9999 );
22+ hash1Map .put (null ,-777 );
23+ System .out .println ("\n Newly created HashMap status : " +hash1Map );
24+ System .out .println ("\n Size of HashMap / No of elements : " +hash1Map .size ());
25+ System .out .println ("\n Check key exits in hashMap : " +hash1Map .containsKey (null ));
26+ System .out .println ("\n Check value exits in hashMap : " +hash1Map .containsValue (9999 ));
27+ System .out .println ("\n Check value -1 exits in hashMap : " +hash1Map .containsValue (-1 ));
28+ System .out .println ("\n Get hashcode of hashMap : " +hash1Map .hashCode ());
29+ 30+ //Iteration over hashMap.
31+ Set <Entry > entrySetRef =hash1Map .entrySet ();
32+ //Using filter on-top of collections
33+ entrySetRef .parallelStream ()
34+ .filter (t ->t .getKey ()!=null )
35+ .forEach (t ->
36+ System .out .println ("\n Key : " +t .getKey ()+"=>hashcode : " +t .getKey ().hashCode ()+" --> Value : " +t .getValue ()+" " )
37+ );
38+ 39+ //Time complexity is constant - O(1) - to access element
40+ System .out .println ("\n Access element using key : " +hash1Map .get (null ));
41+ 42+ }
43+ 44+ }
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