1    // Word List using an ARRAYLIST <>()
2    
3    package arraylistplay;
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 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               readWords();
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       public static Scanner establishScanner(String fn) throws FileNotFoundException {
35           String separator = File.separator;
36   //        String homeDirectory = System.getProperty("user.home");
37           String path = "data" + separator;
38           String fullFileName = path + fn;
39           return new Scanner(new File(fullFileName));
40       }
41   
42       private static void readWords() throws FileNotFoundException {
43           Scanner scanner = establishScanner("WordSet.txt");
44           while (scanner.hasNext()) {
45               words.add(numberOfWords, scanner.next());
46               numberOfWords = numberOfWords + 1;
47           }
48       }
49   
50       private static void displayWords() {
51           for (int x = 0; x < numberOfWords; x=x+1) {
52               System.out.println(words.get(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           }
62           else if (command.equalsIgnoreCase("PRINT")) {
63               interpreterPrintCommand();
64           }
65           else if (command.equalsIgnoreCase("SWAP")) {
66               interpreterSwapCommand();
67           }
68           else if (command.equalsIgnoreCase("ADD")) {
69               interpreterAddCommand();
70           }
71           else if (command.equalsIgnoreCase("HELP")) {
72               interpreterHelpCommand();
73           }
74           else if (command.equalsIgnoreCase("EXIT")) {
75               System.exit(0);
76           }
77           else {
78               System.out.println("### Unrecognizable command: " + command);
79           }
80           interpreter();
81       }
82   
83       private static void interpreterDisplayCommand() {
84           displayWords();
85       }
86   
87       private static void interpreterPrintCommand() {
88           String operand = commandReader.next();
89           if (operand.equalsIgnoreCase("FIRST")) {
90               System.out.println(words.get(0));
91           }
92           else if (operand.equalsIgnoreCase("LAST")) {
93               System.out.println(words.get(numberOfWords - 1));
94           }
95           else {
96               int index = Integer.valueOf(operand);
97               System.out.println(words.get(index - 1));
98           }
99       }
100  
101  
102      private static void interpreterHelpCommand() {
103          System.out.println("HELP - display the menu of commands");
104          System.out.println("DISPLAY - display the list of numbers");
105          System.out.println("PRINT - print the number (FIRST, LAST; nth");
106          System.out.println("SWAP - exchange two elements (nth;mth)");
107          System.out.println("ADD - add a number to the list (FIRST;LAST)");
108          System.out.println("EXIT - terminate the program");
109      }
110  
111      private static void interpreterSwapCommand() {
112          int position1 = commandReader.nextInt();
113          int position2 = commandReader.nextInt();
114          String temp = words.get(position1 - 1);
115          words.set(position1 - 1, words.get(position2 - 1));
116          words.set(position2 - 1, temp);
117      }
118  
119      private static void interpreterAddCommand() {
120          String position = commandReader.next();
121          if (position.equalsIgnoreCase("LAST")) {
122              addLast();
123          }
124          else if (position.equalsIgnoreCase("FIRST")) {
125              addFirst();
126          }
127          else {
128              System.out.println("### invalid operand for add command");
129          }
130          numberOfWords = numberOfWords + 1;
131      }
132  
133      private static void addLast() {
134          words.add(numberOfWords, commandReader.next());
135      }
136  
137      private static void addFirst() {
138          words.add(0, commandReader.next());
139      }
140  }