Some basics of using Java Map

. 1          // the Map Key value is not the same, value may be the same value
 2          // the Entry HashMap objects are randomly oriented
 . 3          
. 4          // instantiate. 1 
. 5          the Map <String, String> Maps = new new HashMap <> ();
 . 6          // instantiate 2 
. 7          the Map <String, String> = entends new new the HashMap <> ();
 . 8  
. 9          // additive elements 
10          maps.put ( "A", "Joe Smith" );
 . 11          maps.put ( "b" "John Doe" );
 12 is          maps.put ( "C", "Wang Wu" );
 13 is          entends.put ( "D","Zhao Si orphan" );
 14         entends.put ( "pent", "king pock" );
 15  
16          // instantiate an absorbent of Example 2 
. 17          maps.putAll (entends); // presence will remain the original value
 18 is  
. 19          @ added element Return value 
20 is          String str1 = maps.put ( "cyclohexyl", "Wed" );
 21 is          String str2 maps.put = ( "C", "Wang Wu" );
 22 is          System.out.println (str1); // null (formerly absent output null) 
23 is          System.out.println (str2); // Wang Wu (existing output)
 24  
25          // traversal key and value 
26 is          for (of Map.Entry <String, String> entry: Maps.
entrySet()) {
27             System.out.println("key:" + entry.getKey() + ";value:" + entry.getValue());
28         }
29 
30         // foreach遍历（Java8新特性）
31         maps.forEach((k, v) -> System.out.println("key:" + k + ";value:" + v));
32 
33         // 遍历key值1
34         for(String key:maps.keySet()){
35             System.out.println("key:"+key);
36         }
37 
38         // 遍历key值2
39         maps.keySet().forEach(k-> System.out.println("key:"+k));
40 
41         //Value traversal value. 1 
42 is          for (String value: maps.values ()) {
 43 is              System.out.println ( "value:" + value);
 44 is          }
 45  
46 is          // iterate value value 2 
47          . Maps.values () forEach (V-> System.out.println ( "value:" + V));
 48          
49          // query element 
50          String maps.get STR = ( "D" );
 51 is          
52 is          // delete the element 
53 is          maps.remove ( " D " );
 54 is          
55          // Clear 
56 is          maps.clear ();
 57 is          System.out.println (" D: "+ str);    

Reference Bowen: https://www.cnblogs.com/jpwz/p/5680494.html

https://www.cnblogs.com/gongxr/p/7777717.html