1    /* 
2    *A program to perform some basic operations on a list of Strings 
3    * using Java streams. 
4     */
5    
6    
7    package arraylistplay;
8    
9    import java.util.ArrayList;
10   import java.util.Collection;
11   import java.util.List;
12   import java.util.stream.Collectors;
13   
14   
15   public class StreamArrayListProcessing {
16   
17       public static void main(String[] args) {
18           //Point A:  Add some Strings which represent names to an Arraylist.
19           List<String> names = new ArrayList<>();
20           names.add("Holiday, Billie");
21           names.add("Claudel, Camille");
22           names.add("Picasso, Pablo");
23           names.add("Gallen-Kallela, Akseli");
24           names.add("Zotto, Osvaldo");
25           names.add("Harry, Potter");
26           names.add("Khanal, Durga");
27   
28           //  Point B: Use map and the toList collector to create an ArrayList of just the first  names of the names ArrayList.
29           // Use a for loop to print out the names, separated by spaces
30   
31           List<String> firstNamesList =  names.stream()
32                   .map(n -> firstName(n))
33                   .collect(Collectors.toList());
34           System.out.print("First names:");
35           for (String firstName : firstNamesList) {
36               System.out.print(firstName + " ");
37           }
38           System.out.println();
39   
40           //Point C: Use map and the joining collector to create a String of just
41           //the first names of the names ArrayList with each name separated by a comma. Print it.
42           String firstNames= names.stream()
43                   .map(n-> firstName(n))
44                   .collect(Collectors.joining(", "));
45   
46           System.out.println("First names:" + firstNames);
47   
48           //Point D: By Analogy from point C, print a comma-separated list of the last names in the names ArrayList.
49   
50           String lastNames= names.stream()
51                   .map(n-> lastName(n))
52                   .collect(Collectors.joining(","));
53   
54           System.out.println("Last names:" + lastNames);
55   
56           //Point E: Print a comma-separated list of all uppercase first names
57           // from the list of names in the names ArrayList.
58           String upperCaseFirstNames= names.stream()
59                   .map(n-> firstName(n))
60                   .map(n->n.toUpperCase())
61                   .collect(Collectors.joining(", "));
62           System.out.println("Uppercase first names:"+ upperCaseFirstNames);
63   
64           //Point F: print a comma-separated list of all hyphenated last names from the
65           // list of names in the names ArrayList.
66           String hyphenatedLastNames= names.stream()
67                   .map(n-> lastName(n))
68                   .filter(n-> n.contains("-"))
69                   .collect(Collectors.joining(","));
70           System.out.println("Hyphenated last names:"+ hyphenatedLastNames);
71   
72           //Point G: print the integer value of the total length of all names in the names Arraylist.
73           int totalLength= names.stream()
74                   .map(n-> n.length())
75                   .reduce(0,(n1,n2)-> n1 + n2);
76           System.out.println("Total length:"+ totalLength);
77   
78           int totalFirstLength= firstNamesList.stream()
79                   .map(n-> n.length())
80                   .reduce(0,(n1,n2)-> n1 + n2);
81           System.out.println("Total first length:"+ totalFirstLength);
82   
83           int totalProduct= names.stream()
84                   .map(n-> n.length())
85                   .reduce(1,(n1,n2)-> n1 * n2);
86           System.out.println("Total Product:"+ totalProduct);
87   
88   
89       }
90       private static String firstName (String directoryStyleName){
91               int commaPosition = directoryStyleName.indexOf(",");
92               String firstName = directoryStyleName.substring(commaPosition + 2);
93   
94               return firstName;
95           }
96       private static String lastName(String directoryStyleName) {
97           int commaPosition= directoryStyleName.indexOf(",");
98           String lastName= directoryStyleName.substring(0,commaPosition);
99   
100          return lastName;
101      }
102  
103      }
104