1 /*
  2  * Program featuring an array to store and interactively manipulate a list
  3  * of words
  4  */
  5 package arraylistplay;
  6 
  7 import java.io.File;
  8 import java.io.FileNotFoundException;
  9 import java.io.PrintWriter;
 10 import java.util.ArrayList;
 11 import java.util.Scanner;
 12 import java.util.logging.Level;
 13 import java.util.logging.Logger;
 14 
 15 /**
 16  *
 17  * @author akc
 18  */
 19 public class WordList {
 20 
 21     // VARIABLES LOCAL TO THE CLASS, AND HENCE GLOBAL TO THE METHODS
 22     private static ArrayList<String> words = new ArrayList<>();
 23     private static Scanner commandReader = new Scanner(System.in);
 24     
 25     /**
 26      * @param args the command line arguments
 27      */
 28     public static void main(String[] args) {
 29         try {
 30             // ESTABLISH THE ARRAY OF WORDS
 31             readWords();
 32             // CHECK THE DATA
 33             System.out.println("\nThe original list of words ...");
 34             displayWords();
 35             // ENTER THE INTERPRETER
 36             interpreter();
 37         } catch (FileNotFoundException ex) {
 38             System.out.println("The file was not found. Please think again.");
 39             System.exit(-1);
 40         }
 41     }
 42         
 43     // Assuming that the data file will be found in the public_html/data
 44     // subdirectory of the user’s home directory.
 45     private static Scanner establishScanner(String fn) throws FileNotFoundException {
 46         String separator = System.getProperty("file.separator");
 47         String homeDirectory = System.getProperty("user.home");
 48         String path = homeDirectory + separator + "CS1Files/data" + separator;
 49         String fullFileName = path + fn;
 50         return new Scanner(new File(fullFileName));
 51     }
 52 
 53     private static void readWords() throws FileNotFoundException {
 54         Scanner scanner = establishScanner("WordSet.text");
 55         while (scanner.hasNext()) {
 56             words.add(scanner.next());
 57         }
 58     }
 59 
 60     private static void displayWords() {
 61         for ( String word : words ) {
 62             System.out.println(word);
 63         }
 64     }
 65 
 66     private static void interpreter() {
 67         System.out.print(">>> ");
 68         String command = commandReader.next();
 69         if (command.equalsIgnoreCase("DISPLAY")) {
 70             interpreterDisplayCommand();
 71         } else if (command.equalsIgnoreCase("PRINT")) {
 72             interpretPrintCommand();
 73         } else if (command.equalsIgnoreCase("SWAP")) {
 74             interpretSwapCommand();
 75         } else if (command.equalsIgnoreCase("ADD")) {
 76             interpretAddCommand();
 77         } else if (command.equalsIgnoreCase("HELP")) {
 78             interpretHelpCommand();
 79         } else if (command.equalsIgnoreCase("EXIT")) {
 80             System.exit(0);
 81         } else {
 82             System.out.println("### Unrecognizable command: " + command);
 83         }
 84         interpreter();
 85     }
 86 
 87     private static void interpreterDisplayCommand() {
 88         displayWords();
 89     }
 90 
 91     private static void interpretPrintCommand() {
 92         String operand = commandReader.next();
 93         if (operand.equalsIgnoreCase("FIRST")) {
 94             System.out.println(words.get(0));
 95         } else if (operand.equalsIgnoreCase("LAST")) {
 96             System.out.println(words.get(words.size() - 1));
 97         }else if (Integer.valueOf(operand) > words.size()) {
 98             System.out.println("null");
 99         }else {
100             int index = Integer.valueOf(operand);
101             System.out.println(words.get(index - 1));
102         }
103     }
104 
105     private static void interpretHelpCommand() {
106         System.out.println("HELP - display a menu of commands");
107         System.out.println("DISPLAY - display the list of words");
108         System.out.println("PRINT - print a word (FIRST;LAST;nth)");
109         System.out.println("SWAP - exchange two elements (nth;mth)");
110         System.out.println("ADD - add a word to the list (FIRST;LAST)");
111         System.out.println("EXIT - terminate execution of the program");
112     }
113 
114     private static void interpretSwapCommand() {
115         int position1 = commandReader.nextInt();
116         int position2 = commandReader.nextInt();
117         String temp = words.get(position1 - 1);
118         words.set(position1 - 1, words.get(position2 - 1));
119         words.set(position2 - 1,temp);
120     }
121 
122     private static void interpretAddCommand() {
123         String position = commandReader.next();
124         if (position.equalsIgnoreCase("LAST")) {
125             addLast();
126         } else if (position.equalsIgnoreCase("FIRST")) {
127             addFirst();
128         } else {
129             System.out.println("### invalid operand for add command");
130         }
131     }
132 
133     private static void addLast() {
134         words.add(commandReader.next());
135     }
136 
137     private static void addFirst() {
138         words.add(0, commandReader.next());
139     }
140 }
141     
142