1 /* 2 * Program featuring an array to store and interactively manipulate a list of numbers. 3 */ 4 package arraylistplay; 5 6 import java.io.File; 7 import java.io.FileNotFoundException; 8 import java.util.ArrayList; 9 import java.util.Scanner; 10 11 public class WordList { 12 // VARIABLES LOCAL TO THE CLASS, AND HENCE GLOBAL TO THE METHODS 13 private static ArrayList<String> words = new ArrayList<>(); 14 private static int numberOfNumbers = 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 NUMBERS 20 readNumbers(); 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 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 readNumbers() throws FileNotFoundException { 43 Scanner scanner = establishScanner("Wordlist.txt"); 44 while (scanner.hasNext()) { 45 words.add(scanner.next()); 46 numberOfNumbers = numberOfNumbers + 1; 47 } 48 } 49 50 private static void displayNumbers() { 51 for (String word:words){ 52 System.out.println(word); 53 } 54 } 55 56 private static void interpreter() { 57 System.out.print(">>> "); 58 String command = commandReader.next(); 59 if (command.equalsIgnoreCase("DISPLAY")) { 60 interpreterDisplayCommand(); 61 } else if (command.equalsIgnoreCase("PRINT")) { 62 interpretPrintCommand(); 63 } else if (command.equalsIgnoreCase("SWAP")) { 64 interpretSwapCommand(); 65 } else if (command.equalsIgnoreCase("ADD")) { 66 interpretAddCommand(); 67 } else if (command.equalsIgnoreCase("HELP")) { 68 interpretHelpCommand(); 69 } else if (command.equalsIgnoreCase("EXIT")) { 70 System.exit(0); 71 } else { 72 System.out.println("### Unrecognizable command: " + command); 73 } 74 interpreter(); 75 } 76 77 private static void interpreterDisplayCommand() { 78 displayNumbers(); 79 } 80 81 private static void interpretPrintCommand() { 82 String operand = commandReader.next(); 83 if (operand.equalsIgnoreCase("FIRST")) { 84 System.out.println(words.get(0)); 85 } else if (operand.equalsIgnoreCase("LAST")) { 86 System.out.println(words.get(words.size() - 1)); 87 } else { 88 int index = Integer.valueOf(operand); 89 System.out.println(words.get(index - 1)); 90 } 91 } 92 93 private static void interpretHelpCommand() { 94 System.out.println("HELP - display a menu of commands"); 95 System.out.println("DISPLAY - display the list of words"); 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 interpretSwapCommand() { 103 int position1 = commandReader.nextInt(); 104 int position2 = commandReader.nextInt(); 105 String temp = words.get(position1-1); 106 words.set(position1-1,words.get(position2-1)); 107 words.set(position2-1,temp); 108 } 109 110 private static void interpretAddCommand() { 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 numberOfNumbers = numberOfNumbers + 1; 120 } 121 122 private static void addLast() { 123 words.add(commandReader.next()); 124 125 } 126 127 private static void addFirst() { 128 words.add(0,commandReader.next()); 129 130 } 131 } 132