1 /*
  2     * Program featuring an array to store and interactively manipulate a list
  3  */
  4 package arrayplay;
  5 
  6 import java.io.File;
  7 import java.io.FileNotFoundException;
  8 import java.util.Scanner;
  9 
 10 /**
 11  *
 12  * @author ffrigin
 13  */
 14 public class NumberList {
 15 
 16     // VARIABLES LOCAL TO THE CLASS, AND HENCE GLOBAL TO THE METHODS
 17     private static final int LIMIT = 1000;
 18     private static int[] numbers = new int[LIMIT];
 19     private static int numberOfNumbers = 0;
 20     private static Scanner commandReader = new Scanner(System.in);
 21 
 22     /**
 23      * @param args the command line arguments
 24      */
 25     public static void main(String[] args) {
 26         try {
 27             // ESTABLISH THE ARRAY OF NUMBERS
 28             readNumbers();
 29             // CHECK THE DATA
 30             System.out.println("\nThe original list of numbers...");
 31             displayNumbers();
 32             // ENTER THE INTERPRETER
 33             interpreter();
 34         } catch (FileNotFoundException ex) {
 35             System.out.println("The file was not found. Please think again.");
 36             System.exit(-1);
 37         }
 38     }
 39 
 40     // Assuming that the data file will be found in the public_html/data 
 41     // subdirectory of the user's home directory
 42     private static Scanner establishScanner(String fn) throws FileNotFoundException {
 43         String separator = System.getProperty("file.separator");
 44         String homeDirectory = System.getProperty("user.home");
 45         String path = homeDirectory + separator + "CS1Files" + separator + "data" + separator;
 46         String fullFileName = path + fn;
 47         return new Scanner(new File(fullFileName));
 48     }
 49 
 50     private static void readNumbers() throws FileNotFoundException {
 51         Scanner scanner = establishScanner("NumberSet.text");
 52         while (scanner.hasNext()) {
 53             numbers[numberOfNumbers] = scanner.nextInt();
 54             numberOfNumbers = numberOfNumbers + 1;
 55         }
 56     }
 57 
 58     private static void displayNumbers() {
 59         for (int x = 0; x < numberOfNumbers; x = x + 1) {
 60             System.out.println(numbers[x]);
 61         }
 62     }
 63 
 64     private static void interpreter() {
 65         System.out.print(">>> ");
 66         String command = commandReader.next();
 67         if (command.equalsIgnoreCase("DISPLAY")) {
 68             interpreterDisplayCommand();
 69         } else if (command.equalsIgnoreCase("PRINT")) {
 70             interpretPrintCommand();
 71         } else if (command.equalsIgnoreCase("SWAP")) {
 72             interpretSwapCommand();
 73         } else if (command.equalsIgnoreCase("ADD")) {
 74             interpretAddCommand();
 75         } else if (command.equalsIgnoreCase("HELP")) {
 76             interpretHelpCommand();
 77         } else if (command.equalsIgnoreCase("EXIT")) {
 78             System.exit(0);
 79         } else {
 80             System.out.println("### Unrecognizable command: " + command);
 81         }
 82             interpreter();
 83         }
 84     
 85 
 86     private static void interpreterDisplayCommand() {
 87         displayNumbers();
 88     }
 89 
 90     private static void interpretPrintCommand() {
 91         String operand = commandReader.next();
 92         if (operand.equalsIgnoreCase("FIRST")) {
 93             System.out.println(numbers[0]);
 94         } else if (operand.equalsIgnoreCase("LAST")) {
 95             System.out.println(numbers[numberOfNumbers - 1]);
 96         } else {
 97             int index = Integer.valueOf(operand);
 98             System.out.println(numbers[index - 1]);
 99         }
100     }
101 
102     private static void interpretHelpCommand() {
103         System.out.println("HELP - display a menu of commands");
104         System.out.println("DISPLAY - display the list of numbers");
105         System.out.println("PRINT -  print a 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 execution of the program");
109     }
110 
111     private static void interpretSwapCommand() {
112         int position1 = commandReader.nextInt();
113         int position2 = commandReader.nextInt();
114         int temp = numbers[position1 - 1];
115         numbers[position1 - 1] = numbers[position2 - 1];
116         numbers[position2 - 1] = temp;
117     }
118 
119     private static void interpretAddCommand() {
120         String position = commandReader.next();
121         if (position.equalsIgnoreCase("LAST")) {
122             addLast();
123         } else if (position.equalsIgnoreCase("FIRST")) {
124             addFirst();
125         } else {
126             System.out.println("### invalid operand for add command");
127         }
128         numberOfNumbers = numberOfNumbers + 1;
129 
130     }
131 
132     private static void addLast() {
133         numbers[numberOfNumbers] = commandReader.nextInt();
134 
135     }
136 
137     private static void addFirst() {
138         for (int x = numberOfNumbers; x > 0; x = x - 1) {
139             numbers[x] = numbers[x - 1];
140         }
141         numbers[0] = commandReader.nextInt();
142 
143     }
144 
145 }
146