1    /* 
2    * Program featuring an array to store and interactively manipulate a list of numbers. 
3     */
4    
5    
6    package arrayPlay;
7    
8    import javax.swing.*;
9    import java.io.File;
10   import java.io.FileNotFoundException;
11   import java.util.Scanner;
12   
13   public class NumberList {
14       //Variables local to the class, and hence global to the methods
15       private static final int LIMIT= 1000;
16       private static int[] numbers= new int[LIMIT];
17       private static int numberOfNumbers= 0;
18       private static Scanner commandReader= new Scanner(System.in);
19       
20       public static void main(String[]args) {
21           try {
22   
23               //Establish the array of numbers
24               readNumbers();
25               //Check the data
26               System.out.println("\nThe original list of numbers...");
27               displayNumbers();
28               //Enter the interpreter
29               interpreter();
30           } catch (FileNotFoundException ex) {
31               System.out.println("The file was not found. Please think again.");
32               System.exit(-1);
33   
34           }
35       }
36           private static void readNumbers () throws FileNotFoundException {
37               Scanner scanner = establishScanner("NumberSet.txt");
38               while (scanner.hasNext()) {
39                   numbers[numberOfNumbers] = scanner.nextInt();
40                   numberOfNumbers = numberOfNumbers + 1;
41               }
42           }
43           private static Scanner establishScanner (String fn) throws FileNotFoundException {
44               String separator = File.separator;
45               String homeDirectory = System.getProperty("user.home");
46               String path = homeDirectory + separator + "public_html" + separator + "data" + separator;
47               String fullFileName = path + fn;
48               return new Scanner(new File(fullFileName));
49           }
50           private static void interpreter () {
51               System.out.print(">>>");
52               String command = commandReader.next();
53               if (command.equalsIgnoreCase("DISPLAY")) {
54                   interpreterDisplayCommand();
55               } else if (command.equalsIgnoreCase("PRINT")) {
56                   interpretPrintCommand();
57               } else if (command.equalsIgnoreCase("SWAP")) {
58                   interpretSwapCommand();
59               } else if (command.equalsIgnoreCase("ADD")) {
60                   interpretAddCommand();
61               } else if (command.equalsIgnoreCase("HELP")) {
62                   interpretHelpCommand();
63               } else if (command.equalsIgnoreCase("EXIT")) {
64                   System.exit(0);
65               } else {
66                   System.out.println("### Unrecognizable command:" + command);
67   	    }
68   	    interpreter();
69           }
70   
71       private static void interpreterDisplayCommand() {
72           displayNumbers();
73       }
74   
75       private static void displayNumbers() {
76           for (int x= 0; x<numberOfNumbers; x=x+1){
77               System.out.println(numbers[x]);
78           }
79       }
80   
81       private static void interpretPrintCommand() {
82           String operand= commandReader.next();
83           if (operand.equalsIgnoreCase("FIRST")) {
84               System.out.println(numbers[0]);
85           }else if (operand.equalsIgnoreCase("LAST")) {
86               System.out.println(numbers[numberOfNumbers - 1]);
87           }else {
88               int index= Integer.valueOf(operand);
89               System.out.println(numbers[index-1]);
90           }
91       }
92       private static void interpretSwapCommand() {
93           int position1= commandReader.nextInt();
94           int position2= commandReader.nextInt();
95           int temp= numbers[position1-1];
96           numbers[position1-1]= numbers[position2-1];
97           numbers[position2-1]=temp;
98       }
99       private static void interpretHelpCommand() {
100          System.out.println("HELP - display a menu of commands");
101          System.out.println("DISPLAY - display the list of numbers");
102          System.out.println("PRINT- print a number(FIRST; LAST; nth) ");
103          System.out.println("ADD  - add a number to the list(FIRST; LAST)");
104          System.out.println("EXIT - terminate execution of the program");
105      }
106      private static void interpretAddCommand() {
107          String position= commandReader.next();
108          if (position.equalsIgnoreCase("LAST")) {
109              addLast();
110          }else if (position.equalsIgnoreCase("FIRST")) {
111              addFIRST();
112          }else {
113              System.out.println("### invalid operand for add command");
114          }
115          numberOfNumbers= numberOfNumbers+1;
116      }
117      private static void addLast() {
118          numbers[numberOfNumbers]= commandReader.nextInt();
119      }
120      private static void addFIRST(){
121          for (int x= numberOfNumbers; x>0; x=x-1){
122              numbers[x]=numbers[x-1];
123          }
124          numbers[0]= commandReader.nextInt();
125      }
126  
127  }
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