1        /* 
2         * Program featuring an array to store and interactively manipulate a list of numbers. 
3         */
4        package arrayPlay;
5    
6        import java.io.File;
7        import java.io.FileNotFoundException;
8        import java.util.Scanner;
9    
10       public class WordList {
11           // VARIABLES LOCAL TO THE CLASS, AND HENCE GLOBAL TO THE METHODS
12           private static final int LIMIT = 1000;
13           private static String[] words = new String[LIMIT];
14           private static int numberOfWords = 0;
15           private static Scanner commandReader = new Scanner(System.in);
16   
17           public static void main(String[] args) {
18               try {
19                   // ESTABLISH THE ARRAY OF NUMBERS
20                   readNumbers();
21                   // CHECK THE DATA
22                   // System.out.println("nThe original list of numbers ...");
23                   // displayNumbers();
24                   // ENTER THE INTERPRETER
25                   interpreter();
26               } catch (FileNotFoundException ex) {
27                   System.out.println("The file was not found. Please think again.");
28                   System.exit(-1);
29               }
30           }
31   
32           // Assuming that the data file will be found in the public_html/data
33           // subdirectory of the user’s home directory.
34           private static Scanner establishScanner(String fn) throws FileNotFoundException {
35               String separator = File.separator;
36               String homeDirectory = System.getProperty("user.home");
37               String path = homeDirectory + separator + "public_html" + separator + "data" + separator;
38               String fullFileName = path + fn;
39               return new Scanner(new File(fullFileName));
40           }
41   
42           private static void readNumbers() throws FileNotFoundException {
43               Scanner scanner = establishScanner("WordSet.txt");
44               while (scanner.hasNext()) {
45                  words[numberOfWords] = scanner.next();
46                   numberOfWords = numberOfWords + 1;
47               }
48           }
49   
50           private static void displayNumbers() {
51               for (int x = 0; x < numberOfWords; x = x + 1) {
52                   System.out.println(words[x]);
53               }
54           }
55   
56           private static void interpreter() {
57               System.out.print(">>> ");
58               String command = commandReader.next();
59               if (command.equalsIgnoreCase("DISPLAY")) {
60                   interpreterDisplayCommand();
61               } else if (command.equalsIgnoreCase("PRINT")) {
62                   interpretPrintCommand();
63               } else if (command.equalsIgnoreCase("SWAP")) {
64                   interpretSwapCommand();
65               } else if (command.equalsIgnoreCase("ADD")) {
66                   interpretAddCommand();
67               } else if (command.equalsIgnoreCase("HELP")) {
68                   interpretHelpCommand();
69               } else if (command.equalsIgnoreCase("EXIT")) {
70                   System.exit(0);
71               } else {
72                   System.out.println("### Unrecognizable command: " + command);
73               }
74               interpreter();
75           }
76   
77           private static void interpreterDisplayCommand() {
78               displayNumbers();
79           }
80   
81           private static void interpretPrintCommand() {
82               String operand = commandReader.next();
83               if (operand.equalsIgnoreCase("FIRST")) {
84                   System.out.println(words[0]);
85               } else if (operand.equalsIgnoreCase("LAST")) {
86                   System.out.println(words[numberOfWords - 1]);
87               } else {
88                   int index = Integer.valueOf(operand);
89                   System.out.println(words[index]);
90               }
91           }
92   
93           private static void interpretHelpCommand() {
94               System.out.println("HELP - display a menu of commands");
95               System.out.println("DISPLAY - display the list of numbers");
96               System.out.println("PRINT - print a number (FIRST;LAST;nth)");
97               System.out.println("SWAP - exchange two elements (nth;mth)");
98               System.out.println("ADD - add a number to the list (FIRST;LAST)");
99               System.out.println("EXIT - terminate execution of the program");
100          }
101  
102          private static void interpretSwapCommand() {
103              int position1 = commandReader.nextInt();
104              int position2 = commandReader.nextInt();
105              String temp = words[position1];
106              words[position1] = words[position2];
107              words[position2] = temp;
108          }
109  
110          private static void interpretAddCommand() {
111              String position = commandReader.next();
112              if (position.equalsIgnoreCase("LAST")) {
113                  addLast();
114              } else if (position.equalsIgnoreCase("FIRST")) {
115                  addFirst();
116              } else {
117                  System.out.println("### invalid operand for add command");
118              }
119              numberOfWords = numberOfWords + 1;
120          }
121  
122          private static void addLast() {
123              words[numberOfWords] = commandReader.next();
124          }
125  
126          private static void addFirst() {
127              for (int x = numberOfWords; x > 0; x = x - 1) {
128                  words[x] = words[x - 1];
129              }
130              words[0] = commandReader.next();
131          }
132      }