1    
2    
3    package arraylist;
4    
5    import java.io.File;
6    import java.io.FileNotFoundException;
7    import java.util.ArrayList;
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 ArrayList<String> words = new ArrayList<>(LIMIT);
14       private static int numberOfNumbers = 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               readWordsFromFile();
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 inputFileName) 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 + inputFileName;
39           return new Scanner(new File(fullFileName));
40       }
41   
42       private static void readWordsFromFile() throws FileNotFoundException {
43           Scanner scanner = establishScanner("WordSet.txt");
44           while (scanner.hasNext()) {
45               String word = scanner.next();
46               words.add(word);
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           for (String w : words){
55               System.out.println(w);
56           }
57       }
58   
59       private static void interpreter() {
60           System.out.print(">>> ");
61           String command = commandReader.next();
62           if (command.equalsIgnoreCase("DISPLAY")) {
63               interpreterDisplayCommand();
64           } else if (command.equalsIgnoreCase("PRINT")) {
65               interpretPrintCommand();
66           } else if (command.equalsIgnoreCase("SWAP")) {
67               interpretSwapCommand();
68           } else if (command.equalsIgnoreCase("ADD")) {
69               interpretAddCommand();
70           } else if (command.equalsIgnoreCase("HELP")) {
71               interpretHelpCommand();
72           } else if (command.equalsIgnoreCase("EXIT")) {
73               System.exit(0);
74           } else {
75               System.out.println("### Unrecognizable command: " + command);
76           }
77           interpreter();
78       }
79   
80       private static void interpreterDisplayCommand() {
81           displayNumbers();
82       }
83   
84       private static void interpretPrintCommand() {
85           String operand = commandReader.next();
86           if (operand.equalsIgnoreCase("FIRST")) {
87               System.out.println(words.get(0));
88           } else if (operand.equalsIgnoreCase("LAST")) {
89               System.out.println(words.get(words.size()-1));
90           } else {
91               int index = Integer.valueOf(operand);
92               System.out.println(words.get(index - 1));
93           }
94       }
95   
96       private static void interpretHelpCommand() {
97           System.out.println("HELP - display a menu of commands");
98           System.out.println("DISPLAY - display the list of words");
99           System.out.println("PRINT - print a word (FIRST;LAST;nth)");
100          System.out.println("SWAP - exchange two elements (nth;mth)");
101          System.out.println("ADD - add a number to the list (FIRST;LAST)");
102          System.out.println("EXIT - terminate execution of the program");
103      }
104  
105      private static void interpretSwapCommand() {
106          int position1 = commandReader.nextInt();
107          int position2 = commandReader.nextInt();
108          String temp = words.get(position1 - 1);
109          words.set ((position1 - 1), words.get(position2 - 1));
110          words.set(position2 - 1, temp);
111      }
112  
113      private static void interpretAddCommand() {
114          String position = commandReader.next();
115          if (position.equalsIgnoreCase("LAST")) {
116              addLast();
117          } else if (position.equalsIgnoreCase("FIRST")) {
118              addFirst();
119          } else {
120              System.out.println("### invalid operand for add command");
121          }
122          numberOfNumbers = numberOfNumbers + 1;
123      }
124  
125      private static void addLast() {
126          words.add(words.size(), commandReader.next());
127      }
128  
129      private static void addFirst() {
130          for (int x = numberOfNumbers; x > 0; x = x - 1) {
131              words.add(0,commandReader.next());
132              //           words[x] = words[x-1];
133          }
134      }
135  }