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   
14       private static ArrayList < String> numbers = new ArrayList <String> ();
15       private static int numberOfNumbers = 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   //        System.out.println(homeDirectory);
39           String path = homeDirectory + separator + "public_html" + separator + "data" + separator;
40           String fullFileName = path + fn;
41           return new Scanner(new File(fullFileName));
42       }
43   
44       private static void readNumbers() throws FileNotFoundException {
45           Scanner scanner = establishScanner("WordSet.txt");
46   
47           //checks to see if there is any thing else left to scan
48           while (scanner.hasNext()) {
49   
50               // gives you the next value that the scanner sees
51               numbers.add(scanner.next());
52               numberOfNumbers = numberOfNumbers + 1;
53           }
54       }
55   
56   
57       // Display everything in arraylist
58       private static void displayNumbers() {
59           //ForEach- the functions in the for each block will be applied to everything in the stream
60           numbers.stream().forEach( x -> System.out.println(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       private static void interpreterDisplayCommand() {
86           displayNumbers();
87       }
88   
89       private static void interpretPrintCommand() {
90           String operand = commandReader.next();
91           if (operand.equalsIgnoreCase("FIRST")) {
92               System.out.println (numbers.get(0));
93           } else if (operand.equalsIgnoreCase("LAST")) {
94               System.out.println(numbers.get(numberOfNumbers - 1));
95           } else {
96               int index = Integer.valueOf(operand);
97               System.out.println(numbers.get(index - 1));
98           }
99       }
100  
101      private static void interpretHelpCommand() {
102          System.out.println("HELP - display a menu of commands");
103          System.out.println("DISPLAY - display the list of numbers");
104          System.out.println("PRINT - print a number (FIRST;LAST;nth)");
105          System.out.println("SWAP - exchange two elements (nth;mth)");
106          System.out.println("ADD - add a number to the list (FIRST;LAST)");
107          System.out.println("EXIT - terminate execution of the program");
108      }
109  
110      private static void interpretSwapCommand() {
111          int position1 = commandReader.nextInt();
112          int position2 = commandReader.nextInt();
113          //temporary
114          String temp = numbers.get(position1 - 1);
115  
116          //we took out what was in position 1-1 and moved that to temp. We copied and now position 1 is empty so we copy
117          //what was in position 2 to position 1
118  
119          numbers.add(position1-1, numbers.get(position2-1));
120          numbers.remove(position1);
121          numbers.add(position2-1, temp);
122          numbers.remove (position2);
123      }
124  
125      private static void interpretAddCommand() {
126          String position = commandReader.next();
127          if (position.equalsIgnoreCase("LAST")) {
128              addLast();
129          } else if (position.equalsIgnoreCase("FIRST")) {
130              addFirst();
131          } else {
132              System.out.println("### invalid operand for add command");
133          }
134          numberOfNumbers = numberOfNumbers + 1;
135      }
136  
137      private static void addLast() {
138          //whenever we add something to an arraylist it gets added to the end of the arraylist.
139          numbers.add (commandReader.next());
140      }
141  
142      private static void addFirst() {
143  
144          numbers.add(0, commandReader.next());
145  
146  
147  
148      }
149  }
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