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