1 /* 2 *Program featuring an array to store and interactively manipulate a list of numbers. 3 */ 4 5 package arrayplay; 6 7 import java.io.File; 8 import java.io.FileNotFoundException; 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 final int LIMIT = 1000; 14 private static String[] words = new String[LIMIT]; 15 private static int numberOfWords = 0; 16 private static Scanner commandReader = new Scanner(System.in); 17 18 public static void main(String[] args) { 19 try { 20 // ESTABLISH THE ARRAY OF NUMBERS 21 readNumbers(); 22 // CHECK THE DATA 23 // System.out.println("nThe original list of numbers ..."); 24 // displayNumbers(); 25 // ENTER THE INTERPRETER 26 interpreter(); 27 } catch (FileNotFoundException ex) { 28 System.out.println("The file was not found. Please think again."); 29 System.exit(-1); 30 } 31 } 32 33 // Assuming that the data file will be found in the public_html/data 34 // subdirectory of the user’s home directory. 35 private static Scanner establishScanner(String fn) throws FileNotFoundException{ 36 String separator = File.separator; 37 String homeDirectory = System.getProperty("user.home"); 38 String path = homeDirectory + separator + "public_html" + separator + "data" + separator; 39 String fullFileName = path + fn ; 40 return new Scanner(new File(fullFileName)); 41 } 42 43 private static void readNumbers()throws FileNotFoundException{ 44 Scanner scanner = establishScanner("WordSet.txt"); 45 while (scanner.hasNext()){ 46 words[numberOfWords] = scanner.next(); 47 numberOfWords = numberOfWords + 1; 48 } 49 } 50 51 private static void displayNumbers(){ 52 for (int x = 0; x < numberOfWords; x=x+1){ 53 System.out.println(words[x]); 54 } 55 } 56 57 private static void interpreter() { 58 System.out.print(">>> "); 59 String command =commandReader.next(); 60 if(command.equalsIgnoreCase("display")){ 61 interpreterDisplayCommand(); 62 }else if (command.equalsIgnoreCase("print")){ 63 interpretPrintCommand(); 64 }else if (command.equalsIgnoreCase("swap")){ 65 interpretSwapCommand(); 66 }else if (command.equalsIgnoreCase("add")){ 67 interpretAddCommand(); 68 }else if (command.equalsIgnoreCase("help")){ 69 interpretHelpCommand(); 70 }else if (command.equalsIgnoreCase("exit")){ 71 System.exit(0); 72 }else { 73 System.out.println("### Unrecognizable command" + command); 74 } 75 interpreter(); 76 } 77 private static void interpreterDisplayCommand(){ 78 displayNumbers(); 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 } 109 110 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 numberOfWords = numberOfWords + 1; 120 } 121 private static void addLast(){ 122 words[numberOfWords] = commandReader.next(); 123 } 124 private static void addFirst(){ 125 for (int x = numberOfWords; x > 0; x=x-1){ 126 words[x] = words[x-1]; 127 } 128 words[0] = commandReader.next(); 129 } 130 } 131