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StreamArrayListProcessing.java
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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 string 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("Galeen-Kallella, Akseli");
21 names.add("Zotto, Osvaldo");
22 names.add("Curry, Steph");
23 names.add("Carney, Emily");
24 names.add("TIller, Chyenne");
25 names.add("Sackey-Mensah, Mariah");
26
27 //POINT B: Use map and the toList collector to create an ArrayList of just
28 // the first names of the names ArrayList. Use a for loop to print
29 // 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.println("First Name: ");
35 for (String firstName : firstNamesList) {
36 System.out.print(firstName + " "); }
37 System.out.println();
38
39 //POINT C: Use map and the joining collector to create a String of just
40 // the first names of the names ArrayList with each name separated
41 // by a coma. Print it.
42
43 String firstNames = names.stream()
44 .map(n -> firstName(n))
45 .collect(Collectors.joining(", "));
46 System.out.println("First Names: " + firstNames);
47
48 //POINT D: By analogy from point C, print a comma-separated list of the
49 // last names in the names ArrayList.
50
51 String lastNames = names.stream()
52 .map(n->lastName(n))
53 .collect(Collectors.joining(", "));
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
59 String upperCaseFirstNames = names.stream()
60 .map(n -> firstName(n))
61 .map(n -> n.toUpperCase())
62 .collect(Collectors.joining(", "));
63 System.out.println("UpperCase First Names: " + upperCaseFirstNames);
64
65 //POINT F: Print a comma-separated list of all hyphenated last names
66 // from the list of names in the names ArrayList.
67
68 String hyphenated = names.stream()
69 .map(n -> lastName(n))
70 .filter(n->n.contains("-"))
71 .collect(Collectors.joining(", "));
72 System.out.println("All Hyphenated Last Names: " + hyphenated);
73
74 //POINT G: Print the integer value of the total length
75 // of all names in the names ArrayList.
76
77 int totalLength = names.stream()
78 .map(n -> n.length())
79 .reduce(0, (n1, n2) -> n1 + n2);
80 System.out.println("Total Length:" + totalLength);
81
82 //POINT H: Print the integer value of the total length of all
83 // first names in the names ArrayList.
84
85 int firstNameLength = names.stream()
86 .map(n -> firstName(n))
87 .map(n -> n.length())
88 .reduce(0, (n1, n2) -> n1 + n2);
89 System.out.println("The Length Of The First Name:" + firstNameLength);
90
91 //POINT I: Print the integer value of the product of the length of
92 // all first names in the names ArrayList.
93
94 int productLength = names.stream()
95 .map(n -> firstName(n))
96 .map(n -> n.length())
97 .reduce(1, (n1, n2) -> n1 * n2);
98 System.out.println("The Product Of The Length Of All First Names: " + productLength);
99 }
100
101
102 private static String firstName(String directoryStyleName) {
103 return (directoryStyleName.substring(directoryStyleName.lastIndexOf((" "))));
104 }
105
106 private static String lastName(String directoryStyleName) {
107 return (directoryStyleName.substring(0,directoryStyleName.lastIndexOf((","))));
108 }
109
110 private static List<String> hyphenatedNames(List<String> names) {
111 List<String> hyphenateds = new ArrayList<>();
112 for (String name : names) {
113 if (name.contains("-")) {
114 hyphenateds.add(name);
115 }
116 }
117 return hyphenateds;
118 }
119
120 }
121
122