1 /* 2 *Program featuring an arraylist to store and interactively manipulate a list of words. 3 */ 4 package arraylistplay; 5 6 import java.io.File; 7 import java.io.FileNotFoundException; 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 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 //displayNumber(); 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 private static Scanner establishScanner(String fn) throws FileNotFoundException { 35 String separator = File.separator; 36 String homeDirectory = System.getProperty("user.home"); 37 String path = homeDirectory + separator + "public_html" + separator + "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[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[x]); 53 } 54 } 55 56 private static void interpreter() { 57 System.out.println(">>> "); 58 String command = commandReader.next(); 59 if (command.equalsIgnoreCase("DISPLAY")) { 60 interpreterDisplayCommand(); 61 } else if (command.equalsIgnoreCase("PRINT")) { 62 interpreterPrintCommand(); 63 }else if (command.equalsIgnoreCase("SWAP")) { 64 interpreterSwapCommand(); 65 }else if (command.equalsIgnoreCase("ADD")) { 66 interpreterAddCommand(); 67 }else if (command.equalsIgnoreCase("HELP")) { 68 interpreterHelpCommand(); 69 }else if (command.equalsIgnoreCase("EXIT")) { 70 System.exit(0); 71 }else { 72 System.out.println("### Unrecognized command: " + command); 73 } 74 interpreter(); 75 } 76 77 private static void interpreterDisplayCommand() { 78 displayWords(); 79 } 80 81 private static void interpreterPrintCommand() { 82 String operand = commandReader.next(); 83 if (operand.equalsIgnoreCase("FIRST")) { 84 System.out.println(words[0]); 85 }else if (operand.equalsIgnoreCase("LAST")) { 86 System.out.println(words[numberOfWords - 1]); 87 }else { 88 int index = Integer.valueOf(operand); 89 System.out.println(words[index - 1]); 90 } 91 } 92 93 private static void interpreterHelpCommand() { 94 System.out.println("HELP - display a menu of commands"); 95 System.out.println("DISPLAY - display the list of numbers"); 96 System.out.println("PRINT - print a number (FIRST;LAST;nth"); 97 System.out.println("SWAP - exchange two elements (nth;mth)"); 98 System.out.println("ADD - add a number to the list (FIRST;LAST)"); 99 System.out.println("EXIT - terminate execution of the program "); 100 } 101 102 private static void interpreterSwapCommand() { 103 int position1 = commandReader.nextInt(); 104 int position2 = commandReader.nextInt(); 105 String temp = words[position1 - 1]; 106 words[position1 - 1] = words[position2 - 1]; 107 words[position2 -1] = temp; 108 } 109 110 private static void interpreterAddCommand() { 111 String position = commandReader.next(); 112 if (position.equalsIgnoreCase("LAST")) { 113 addLast(); 114 } else if (position.equalsIgnoreCase("FIRST")) { 115 addFirst(); 116 } else { 117 System.out.println("### invalid operand for add command"); 118 } 119 numberOfWords = numberOfWords + 1; 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(); 130 131 132 } 133 } 134 135 136 137