1    // Word List using an ARRAY OBJECT
2    
3    package arrayPlay;
4    
5    import java.io.File;
6    import java.io.FileNotFoundException;
7    import java.util.Scanner;
8    
9    public class WordList {
10       // VARIABLES LOCAL TO THE CLASS, AND HENCE GLOBAL TO THE METHODS
11       private static final int LIMIT = 1000;
12       private static String[] words = new String[LIMIT];
13       private static int numberOfWords = 0;
14       private static Scanner commandReader = new Scanner(System.in);
15   
16       public static void main(String[] args) {
17           try {
18               // ESTABLISH THE ARRAY OF NUMBERS
19               readWords();
20               // CHECK THE DATA
21               // System.out.println("nThe original list of numbers ...");
22               // displayNumbers();
23               // ENTER THE INTERPRETER
24               interpreter();
25           } catch (FileNotFoundException ex) {
26               System.out.println("The file was not found. Please think again.");
27               System.exit(-1);
28           }
29       }
30   
31       // Assuming that the data file will be found in the public_html/data
32       // subdirectory of the user's home directory.
33       private static Scanner establishScanner(String fn) throws FileNotFoundException {
34           String separator = File.separator;
35           String homeDirectory = System.getProperty("user.home");
36           String path = "data" + separator;
37           String fullFileName = path + fn;
38           return new Scanner(new File(fullFileName));
39       }
40   
41       private static void readWords() throws FileNotFoundException {
42           Scanner scanner = establishScanner("WordSet.txt");
43           while (scanner.hasNext()) {
44               words[numberOfWords] = scanner.next();
45               numberOfWords = numberOfWords + 1;
46           }
47       }
48   
49       private static void displayNumbers() {
50           for (int x = 0; x < numberOfWords; x=x+1) {
51               System.out.println(words[x]);
52           }
53       }
54   
55       private static void interpreter() {
56           System.out.print(">>> ");
57           String command = commandReader.next();
58           if (command.equalsIgnoreCase("DISPLAY")) {
59               interpreterDisplayCommand();
60           }
61           else if (command.equalsIgnoreCase("PRINT")) {
62               interpreterPrintCommand();
63           }
64           else if (command.equalsIgnoreCase("SWAP")) {
65               interpreterSwapCommand();
66           }
67           else if (command.equalsIgnoreCase("ADD")) {
68               interpreterAddCommand();
69           }
70           else if (command.equalsIgnoreCase("HELP")) {
71               interpreterHelpCommand();
72           }
73           else if (command.equalsIgnoreCase("EXIT")) {
74               System.exit(0);
75           }
76           else {
77               System.out.println("### Unrecognizable command: " + command);
78           }
79           interpreter();
80       }
81   
82       private static void interpreterDisplayCommand() {
83           displayNumbers();
84       }
85   
86       private static void interpreterPrintCommand() {
87           String operand = commandReader.next();
88           if (operand.equalsIgnoreCase("FIRST")) {
89               System.out.println(words[0]);
90           }
91           else if (operand.equalsIgnoreCase("LAST")) {
92               System.out.println(words[numberOfWords - 1]);
93           }
94           else {
95               int index = Integer.parseInt(operand);
96               System.out.println(words[index - 1]);
97           }
98       }
99   
100  
101      private static void interpreterHelpCommand() {
102          System.out.println("HELP - display the menu of commands");
103          System.out.println("DISPLAY - display the list of numbers");
104          System.out.println("PRINT - print the number (FIRST, LAST; nth");
105          System.out.println("SWAP - exchange two elements (nth;mth)");
106          System.out.println("ADD - add a number to the list (FIRST;LAST)");
107          System.out.println("EXIT - terminate the program");
108      }
109  
110      private static void interpreterSwapCommand() {
111          int position1 = commandReader.nextInt();
112          int position2 = commandReader.nextInt();
113          String temp = words[position1 - 1];
114          words[position1 - 1] = words[position2 - 1];
115          words[position2 -1] = temp;
116      }
117  
118      private static void interpreterAddCommand() {
119          String position = commandReader.next();
120          if (position.equalsIgnoreCase("LAST")) {
121              addLast();
122          }
123          else if (position.equalsIgnoreCase("FIRST")) {
124              addFirst();
125          }
126          else {
127              System.out.println("### invalid operand for add command");
128          }
129          numberOfWords = numberOfWords + 1;
130      }
131  
132      private static void addLast() {
133          words[numberOfWords] = commandReader.next();
134      }
135  
136      private static void addFirst() {
137          for (int x = numberOfWords; x > 0; x = x - 1) {
138              words[x] = words[x - 1];
139          }
140          words[0] = commandReader.next();
141      }
142  }