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, Camllie");
18           names.add("Picasso, Pablo");
19           names.add("Gallen-Kallela, Akseli");
20           names.add("Zotto, Osvaldo");
21           names.add("Aung, KoKo");
22           names.add("Kyaw-Aung, Khant");
23           // POINT B: Use map and the toList collector to create an ArrayList of just the first names of the names ArrayList.
24           //          Use a for loop to print out the names, separated by spaces.
25           List<String> firstNameList = names.stream().map(n -> firstName(n)).collect(Collectors.toList());
26           System.out.print("First names: ");
27           for (String firstName : firstNameList) {
28               System.out.print(firstName + " ");
29           }
30           System.out.println();
31           // POINT C: Use map and the joining collector to created a String of just the first names of the names ArrayList
32           //          with each name separated by a comma. Print it.
33           String firstNames = names.stream().map(n -> firstName(n)).collect(Collectors.joining(", "));
34           System.out.println("First names: " + firstNames);
35           // POINT D: By analogy from point C, print a comma-separated list of the last names in the names ArrayList.
36           List<String> lastNameList = names.stream().map(n -> lastName(n)).collect(Collectors.toList());
37           System.out.print("Last names: ");
38           for (String lastName : lastNameList) {
39               System.out.print(lastName + " ");
40           }
41           System.out.println();
42           String lastNames = names.stream().map(n -> lastName(n)).collect(Collectors.joining(", "));
43           System.out.println("Last names: " + lastNames);
44           // POINT E: Print a comma-separated list of all uppercase first names from the list of names in the names ArrayList.
45           String upperCaseFirstNames = names.stream().map(n -> firstName(n)).map(n -> n.toUpperCase()).collect(Collectors.joining(", "));
46           System.out.println("Uppercase first names: " + upperCaseFirstNames);
47           // POINT F: Print a comma-separated list of all hyphenated last names from the list of names in the names ArrayList.
48           String hyphenatedLastNames = names.stream().map(n -> lastName(n)).filter(n -> n.contains("-")).collect(Collectors.joining(", "));
49           System.out.println("HyphenatedLastNames: " + hyphenatedLastNames);
50           // POINT G: Print the integer value of the total length of all names in the names ArrayList.
51           int totalLength = names.stream().map(n -> n.length()).reduce(0,(n1,n2) -> n1 + n2);
52           System.out.println("Total Length: " + totalLength);
53           // POINT H: Print the integer value of the total length of all first names in the names ArrayList.
54           int firstNameTotalLength = firstNameList.stream().map(n -> n.length()).reduce(0,(n1, n2) -> n1 + n2);
55           System.out.println("Total first names length: " + firstNameTotalLength);
56           // POINT I: Print the integer value of the product of the length of all first names in the names ArrayList.
57           int namesProductLength = firstNameList.stream().map(n -> n.length()).reduce(1,(n1,n2) -> n1*n2);
58           System.out.println("Total product of names length: " + namesProductLength);
59       }
60       private static String lastName(String directoryStyleName) {
61           int lastNameComma = directoryStyleName.indexOf(",");
62           String lastName = directoryStyleName.substring(0,lastNameComma);
63           return lastName;
64       }
65       private static String firstName(String directoryStyleName) {
66           int firstNameComma = directoryStyleName.indexOf(",");
67           String firstName = directoryStyleName.substring(firstNameComma+2);
68           return firstName;
69       }
70   
71   }