1 /* 2 * Program featuring an array to store and interactively manipulate a list of words. 3 */ 4 package arrayplay; 5 6 import java.io.File; 7 import java.io.FileNotFoundException; 8 import java.util.Scanner; 9 10 public class WordsList { 11 // VARIABLES LOCAL TO THE CLASS, AND HENCE GLOBAL TO THE METHODS 12 private static final int LIMIT = 1000; 13 private static String[] words = new String[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 words 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 // Assuming that the data file will be found in the public_html/data 32 // subdirectory of the user’s home directory. 33 private static Scanner establishScanner(String fn) throws FileNotFoundException { 34 String separator = File.separator; 35 String homeDirectory = System.getProperty("user.home"); 36 String path = homeDirectory + separator + "public_html" + separator + "data" + separator; 37 String fullFileName = path + fn; 38 return new Scanner(new File(fullFileName)); 39 } 40 41 private static void readWords() throws FileNotFoundException { 42 Scanner scanner = establishScanner("WordSet.txt"); 43 while (scanner.hasNext()) { 44 words[numberOfWords] = scanner.next(); 45 numberOfWords = numberOfWords + 1; 46 } 47 } 48 49 private static void displayWords() { 50 for (int x = 0; x < numberOfWords; x = x + 1) { 51 System.out.println(words[x]); 52 } 53 } 54 55 private static void interpreter() { 56 System.out.print(">>> "); 57 String command = commandReader.next(); 58 if (command.equalsIgnoreCase("DISPLAY")) { 59 interpreterDisplayCommand(); 60 } else if (command.equalsIgnoreCase("PRINT")) { 61 interpretPrintCommand(); 62 } else if (command.equalsIgnoreCase("SWAP")) { 63 interpretSwapCommand(); 64 } else if (command.equalsIgnoreCase("ADD")) { 65 interpretAddCommand(); 66 } else if (command.equalsIgnoreCase("HELP")) { 67 interpretHelpCommand(); 68 } else if (command.equalsIgnoreCase("EXIT")) { 69 System.exit(0); 70 } else { 71 System.out.println("### Unrecognizable command: " + command); 72 } 73 interpreter(); 74 } 75 76 private static void interpreterDisplayCommand() { 77 displayWords(); 78 } 79 80 private static void interpretPrintCommand() { 81 String operand = commandReader.next(); 82 if (operand.equalsIgnoreCase("FIRST")) { 83 System.out.println(words[0]); 84 } else if (operand.equalsIgnoreCase("LAST")) { 85 System.out.println(words[numberOfWords - 1]); 86 } else { 87 int index = Integer.valueOf(operand); 88 System.out.println(words[index - 1]); 89 } 90 } 91 92 private static void interpretHelpCommand() { 93 System.out.println("HELP - display a menu of commands"); 94 System.out.println("DISPLAY - display the list of numbers"); 95 System.out.println("PRINT - print a number (FIRST;LAST;nth)"); 96 System.out.println("SWAP - exchange two elements (nth;mth)"); 97 System.out.println("ADD - add a number to the list (FIRST;LAST)"); 98 System.out.println("EXIT - terminate execution of the program"); 99 } 100 101 private static void interpretSwapCommand() { 102 int position1 = commandReader.nextInt(); 103 int position2 = commandReader.nextInt(); 104 String temp = words[position1 - 1]; 105 words[position1 - 1] = words[position2 - 1]; 106 words[position2 - 1] = temp; 107 } 108 109 private static void interpretAddCommand() { 110 String position = commandReader.next(); 111 if (position.equalsIgnoreCase("LAST")) { 112 addLast(); 113 } else if (position.equalsIgnoreCase("FIRST")) { 114 addFirst(); 115 } else { 116 System.out.println("### invalid operand for add command"); 117 } 118 numberOfWords = numberOfWords + 1; 119 } 120 121 private static void addLast() { 122 words[numberOfWords] = commandReader.next(); 123 } 124 125 private static void addFirst() { 126 for (int x = numberOfWords; x > 0; x = x - 1) { 127 words[x] = words[x - 1]; 128 } 129 words[0] = commandReader.next(); 130 } 131 }