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