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    
9    
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               readNumbers();
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 = homeDirectory + separator + "public_html" + separator + "data" + separator;
37           String fullFileName = path + fn;
38           System.out.println(fullFileName);
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")) { interpreterDisplayCommand(); }
60           else if (command.equalsIgnoreCase("PRINT")) { interpreterPrintCommand(); }
61           else if (command.equalsIgnoreCase("SWAP")) { interpreterSwapCommand(); }
62           else if (command.equalsIgnoreCase("ADD")) { interpreterAddCommand(); }
63           else if (command.equalsIgnoreCase("HELP")) { interpreterHelpCommand(); }
64           else if (command.equalsIgnoreCase("EXIT")) { System.exit(0); }
65           else { System.out.println("### Unrecognizable command: " + command); }
66   
67           interpreter();
68       }
69   
70       private static void interpreterDisplayCommand() { displayNumbers(); }
71   
72       private static void interpreterPrintCommand() {
73           String operand = commandReader.next();
74           if (operand.equalsIgnoreCase("FIRST")) { System.out.println(words[0]); }
75           else if (operand.equalsIgnoreCase("LAST")) { System.out.println(words[numberOfWords - 1]); }
76           else {
77               int index = Integer.valueOf(operand);
78               System.out.println(words[index - 1]);
79           }
80       }
81   
82       private static void interpreterHelpCommand() {
83           System.out.println("HELP - display a menu of command");
84           System.out.println("DISPLAY - display the list of numbers");
85           System.out.println("PRINT - print a number (FIRST;LAST;nth)");
86           System.out.println("SWAP - exchange two elements (nth;mth)");
87           System.out.println("ADD - add a number to the list (FIRST;LAST)");
88           System.out.println("EXIT - terminate execution of the program");
89       }
90   
91       private static void interpreterSwapCommand() {
92           int position1 = commandReader.nextInt();
93           int position2 = commandReader.nextInt();
94           String temp = words[position1 - 1];
95           words[position1 - 1] = words[position2 - 1];
96           words[position2 - 1] = temp;
97       }
98   
99       private static void interpreterAddCommand() {
100          String position = commandReader.next();
101          if (position.equalsIgnoreCase("LAST")) {
102              addLast();
103          }
104          else if (position.equalsIgnoreCase("FIRST")) {
105              addFirst();
106          }
107          else {
108              System.out.println("### invalid operand for add command");
109          }
110          numberOfWords = numberOfWords + 1;
111      }
112  
113      private static void addLast() {
114          words[numberOfWords] = commandReader.next();
115      }
116  
117      private static void addFirst() {
118          for (int x = numberOfWords; x > 0; x = x - 1) {
119              words[x] = words[x - 1];
120          }
121          words[0] = commandReader.next();
122      }
123  
124  
125  }
126