1    package arraylistplay;
2    
3    import java.io.File;
4    import java.io.FileNotFoundException;
5    import java.util.ArrayList;
6    import java.util.Scanner;
7    
8    public class WordList {
9        private static ArrayList<String> words = new ArrayList<>();
10       private static int numberOfWords = 0;
11       private static Scanner commandReader = new Scanner(System.in);
12       public static void main(String[] args) {
13           try {
14               readWords();
15               interpreter();
16           } catch (FileNotFoundException ex) {
17               System.out.println("The file was not found. Please think again.");
18               System.exit(-1);
19           }
20       }
21   
22       private static Scanner establishScanner(String fn) throws FileNotFoundException {
23           String separator = System.getProperty("file.separator");
24           String homeDirectory = System.getProperty("user.home");
25           String path = homeDirectory + separator + "public_html" + separator + "data" + separator;
26           String fullFileName = path + fn;
27           return new Scanner(new File(fullFileName));
28       }
29       private static void readWords() throws FileNotFoundException {
30           Scanner scanner = establishScanner("WordSet.txt");
31           while (scanner.hasNext()) {
32               words.add(numberOfWords, scanner.next());
33               numberOfWords ++;
34           }
35       }
36   
37       private static void displayWords() {
38           for (String word : words) {
39               System.out.println(word);
40           }
41       }
42   
43       private static void interpreter() {
44           System.out.print(">>>");
45           String command = commandReader.next();
46           if (command.equalsIgnoreCase("DISPLAY")) {
47               interpreterDisplayCommand();
48           } else if (command.equalsIgnoreCase("PRINT")) {
49               interpreterPrintCommand();
50           } else if (command.equalsIgnoreCase("SWAP")) {
51               interpreterSwapCommand();
52           } else if (command.equalsIgnoreCase("ADD")) {
53               interpreterAddCommand();
54           } else if (command.equalsIgnoreCase("HELP")) {
55               interpreterHelpCommand();
56           } else if (command.equalsIgnoreCase("EXIT")) {
57               System.exit(0);
58           } else {
59               System.out.println("### Unrecognizable command: " + command);
60           }
61           System.out.print("\n");
62           interpreter();
63       }
64   
65       private static void interpreterDisplayCommand() {
66           displayWords();
67       }
68   
69       private static void interpreterPrintCommand() {
70           String operand = commandReader.next();
71           if (operand.equalsIgnoreCase("FIRST")) {
72               System.out.println(words.get(0));
73           } else if (operand.equalsIgnoreCase("LAST")) {
74               System.out.println(words.get(words.size() - 1));
75           } else {
76               int index = Integer.valueOf(operand);
77               System.out.println(words.get(index - 1));         }
78       }
79   
80       private static void interpreterSwapCommand() {
81           int position1 = commandReader.nextInt() - 1;
82           int position2 = commandReader.nextInt() - 1;
83           String temp = words.get(position1);
84           words.set(position1, words.get(position2));
85           words.set(position2, temp);
86       }
87   
88       private static void interpreterAddCommand() {
89   
90           if (isNumeric()) {
91               int index = commandReader.nextInt() - 1;
92               String newWord = commandReader.next();
93               if (index > numberOfWords) {
94                   System.out.println("### invalid operand for add command!");
95               } else {
96                   words.add(index, newWord);
97               }
98           } else {
99               String position = commandReader.next();
100              if (position.equalsIgnoreCase("FIRST")) {//displayWords();
101                  words.add(0, commandReader.next());
102              } else if (position.equalsIgnoreCase("LAST")) {
103                  words.add(words.size(), commandReader.next());
104              } else {
105                  System.out.println("### invalid operand for add command!");
106              }
107  
108          }
109  
110          numberOfWords ++;
111      }
112  
113      private static void interpreterHelpCommand() {
114          System.out.println("HELP    - display menu of commands");
115          System.out.println("DISPLAY - display the list of words");
116          System.out.println("PRINT   - print a word (FIRST; LAST; nth)");
117          System.out.println("SWAP    - exchange two elements (nth; mth)");
118          System.out.println("ADD     - add a word to the list");
119          System.out.println("EXIT    - terminate execution of the program");
120      }
121      private static boolean isNumeric() {
122          return commandReader.hasNextInt();
123      }
124  }
125  
126