1    /* 
2     * A program to perform some basic operations on a list of Strings 
3     * using Java streams 
4     */
5    
6    package arraylists;
7    
8    import java.util.ArrayList;
9    import java.util.List;
10   import java.util.stream.Collectors;
11   
12   public class StreamArrayListProcessing {
13   
14       public static void main(String[] args) {
15           //POINT A: Add some strings which represent names to an ArrayList.
16           List<String> names = new ArrayList<>();
17           names.add("Holiday, Billie");
18           names.add("Claudel, Camille");
19           names.add("Picasso, Pablo");
20           names.add("Gallen-Kallela, Akseli");
21           names.add("Zotto, Osvaldo");
22           names.add("Palta-Tito, Robert");
23           names.add("Arc, Juane");
24   
25           // POINT B: Use map and the toList collector to create an ArrayList of just
26           //          the first names of the names ArrayList. Use a for loop to print
27           //          out the names, separated by spaces.
28           List<String> firstNamesList = names.stream()
29                   .map(n -> firstName(n))
30                   .collect(Collectors.toList());
31   
32           System.out.print("First names: ");
33           for (String firstName : firstNamesList) {
34               System.out.print(firstName + " ");
35           }
36           System.out.println();
37   
38           //POINT C: Use map and the joining collector to create a String of just
39           //         the first names of the names ArrayList with each name separated
40           //         by a comma. Print it.
41           String firstNames = names.stream()
42                   .map(n -> firstName(n))
43                   .collect(Collectors.joining(", "));
44   
45           System.out.println("First names: " + firstNames);
46   
47           //Point D: By analogy from point C, print a comma-separated list of the
48           //         last names in the names ArrayList.
49           String lastNames = names.stream()
50                   .map(n -> lastName(n))
51                   .collect(Collectors.joining(", "));
52   
53           System.out.println("Last names: " + lastNames);
54   
55           //POINT E: Print a comma-separated list of all uppercase first names
56           //         from the list of names in the names ArrayList.
57           String upperCaseFirstNames = names.stream()
58                   .map(n -> firstName(n))
59                   .map(n -> n.toUpperCase())
60                   .collect(Collectors.joining(", "));
61   
62           System.out.println("Uppercase first names: " + upperCaseFirstNames);
63   
64           //POINT F: Print a comma-separated list of all hyphenated last names
65           //         from the 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   
71           System.out.println("Last names with a hypen: " + hyphenatedLastNames);
72   
73           //POINT G: Print the integer value of the total length of all names
74           //         in the names ArrayList.
75           int totalLength = names.stream()
76                   .map(n-> n.length())
77                   .reduce(0, (n1, n2) -> n1 + n2);
78   
79           System.out.println("Total Length: " + totalLength);
80   
81           //POINT H: Print the integer value of the total length of all
82           //         first names in the names ArrayList.
83           int firstNamestotalLength = names.stream()
84                   .map(n -> firstName(n))
85                   .map(n-> n.length())
86                   .reduce(0, (n1, n2) -> n1 + n2);
87   
88           System.out.println("First Name Total Length: " + firstNamestotalLength);
89   
90           //POINT I: Print the integer value of the product of the length of
91           //         all first names in the names ArrayList
92           int firstNamestotalProduct = names.stream()
93                   .map(n -> firstName(n))
94                   .map(n-> n.length())
95                   .reduce(1, (n1, n2) -> n1 * n2);
96   
97           System.out.println("First Name Total Product: " + firstNamestotalProduct);
98       }
99   
100      private static String firstName(String directoryStyleName) {
101          String first = directoryStyleName.substring( directoryStyleName.indexOf(",") + 2, directoryStyleName.length() + 0);
102          return first;
103      }
104  
105      public static String lastName(String directoryStyleName)
106      {
107          String last = directoryStyleName.substring(0, directoryStyleName.indexOf(","));
108          return last;
109      }
110  }