CIS 260 TArray1.java

Code

/*
    TArray1.java
    David Klick
    CIS 260
    3/23/09

    This program is essentially the same as TArray0 with the exception
    that an ordered array is used instead of an unordered array. 
    Due to the array being ordered, there is no insert instruction
    available.
*/

import java.util.*;
import java.io.*;

public class TArray1 {
    private static final int DEFAULT_ARRAY_LENGTH = 10;
    private static BufferedReader in = new BufferedReader(
        new InputStreamReader(System.in));
    public enum Command { QUIT, PRINT, STATUS, HELP, ADD,
                          DELETE_AT, DELETE, FIND
                        }

    private static Hashtable<String, Command> initCommandTable() {
        Hashtable<String, Command> hash = new Hashtable<String, Command>();
        hash.put("QUIT", Command.QUIT);
        hash.put("Q", Command.QUIT);
        hash.put("EXIT", Command.QUIT);
        hash.put("X", Command.QUIT);
        hash.put("PRINT", Command.PRINT);
        hash.put("P", Command.PRINT);
        hash.put("STATUS", Command.STATUS);
        hash.put("STAT", Command.STATUS);
        hash.put("S", Command.STATUS);
        hash.put("HELP", Command.HELP);
        hash.put("H", Command.HELP);
        hash.put("FIND", Command.FIND);
        hash.put("F", Command.FIND);
        hash.put("?", Command.FIND);
        hash.put("ADD", Command.ADD);
        hash.put("A", Command.ADD);
        hash.put("+", Command.ADD);
        hash.put("DELETE", Command.DELETE);
        hash.put("DEL", Command.DELETE);
        hash.put("D", Command.DELETE);
        hash.put("-", Command.DELETE);
        hash.put("DELETE_AT", Command.DELETE_AT);
        hash.put("DELETEAT", Command.DELETE_AT);
        return hash;
    }

    private static void error(String msg) {
        System.out.println(msg);
    }

    private static boolean isInteger(String s) {
        return s.matches("[+-]?[0-9]+");
    }

    private static void println(String msg) {
        System.out.println(msg);
    }

    public static void main(String[] args) throws IOException {
        boolean done = false;
        int arrayLength = DEFAULT_ARRAY_LENGTH;

        // process command line parameters (array length)
        if (args.length == 1) {
            try {
                arrayLength = Integer.parseInt(args[0]);
                if ((arrayLength > 20) || (arrayLength < 5)) {
                    println("Illegal array length specified");
                    arrayLength = DEFAULT_ARRAY_LENGTH;
                }
            } catch (NumberFormatException e) {
                error("Unrecognized command line argument");
                System.exit(0);
            }
        } else if (args.length > 1) {
            error("Only one command line parameter allowed. "
                  + args.length + " found.");
            System.exit(0);
        } else {
            error("No command line parameters found. Using default"
                  + " array size of " + DEFAULT_ARRAY_LENGTH + ".");
        }

        // create array to be used for application
        OrderedArray a = new OrderedArray(arrayLength);

        // intialize command lookup table
        Hashtable<String, Command> commands = initCommandTable();

        // process commands
        displayHelp();
        println("\nProgram ready for processing");
        while (!done) {
            int position, value;
            String[] cmd = getCommand();
            int cmdLength = cmd.length;
            Command command = commands.get(cmd[0].toUpperCase());
            if (command == null) error("Unrecognized command");
            else {
                switch (command) {
                case QUIT:
                    if (cmdLength > 1) error("QUIT command takes no arguments");
                    else done = true;
                    break;
                case PRINT:
                    if (cmdLength > 1) error("PRINT command takes no arguments");
                    else a.print();
                    break;
                case STATUS:
                    if (cmdLength > 1) error("STATUS command takes no arguments");
                    else displayStatus(a);
                    break;
                case HELP:
                    if (cmdLength > 1) error("HELP command takes no arguments");
                    else displayHelp();
                    break;
                case FIND:
                    if (cmdLength != 2) error("FIND command takes one argument");
                    else {
                        if (!isInteger(cmd[1])) error("FIND command argument must be an integer");
                        else {
                            position = a.findElement(Integer.parseInt(cmd[1]));
                            if (position == -1) println(cmd[1] + " not found in array");
                            else println(cmd[1] + " found at position " + position);
                        }
                    }
                    break;
                case ADD:
                    if (cmdLength != 2) error("ADD command takes one argument");
                    else if (!isInteger(cmd[1])) error("ADD command argument must be an integer");
                    else {
                        try {
                            value = Integer.parseInt(cmd[1]);
                            a.addElement(value);
                            println("Element with value " + value + " added");
                        } catch (MyArrayException e) {
                            error(e.getMessage());
                        }
                    }
                    break;
                case DELETE:
                    if (cmdLength != 2) error("DELETE command takes one argument");
                    else if (!isInteger(cmd[1])) error("DELETE argument must be an integer");
                    else {
                        value = Integer.parseInt(cmd[1]);
                        if (a.deleteElement(value)) println("Element with value " + value + " deleted");
                        else println("Element with value " + value + " not found");
                    }
                    break;
                case DELETE_AT:
                    if (cmdLength != 2) error("DELETE_AT command takes one argument");
                    else if (!isInteger(cmd[1])) error("DELETE_AT argument must be an integer");
                    else {
                        position = Integer.parseInt(cmd[1]);
                        try {
                            a.deleteElementAt(position);
                        } catch (MyArrayException e) {
                            println(e.getMessage());
                        }
                    }
                    break;
                default:
                    error("Unrecognized command");
                }
            }
        }
        // end of command processing loop
        println("End of processing");
    }

    public static String[] getCommand() {
        String s = new String();
        System.out.print("\n> ");
        try {
            while ((s = in.readLine()).length() == 0);
        } catch (IOException e) {
            println("I/O Exception");
        }
        s = s.toUpperCase();

        StringTokenizer p = new StringTokenizer(s);
        String[] cmds = new String[p.countTokens()];
        try {
            int i = 0;
            while (p.hasMoreTokens())
                cmds[i++] = p.nextToken();
        } catch (NoSuchElementException e) {
            println(e.getMessage());
        }
        if (cmds.length > 0) {
            // This handles the special case where the first character
            // is a plus (insert) or minus (delete) and is followed by
            // a number without any delimiter in between. This code
            // breaks the single "word" into two separate "words"
            char c = cmds[0].charAt(0);
            if ((cmds[0].length() > 1) && ((c == '+') || (c == '-'))) {
                String[] newCmds = new String[cmds.length + 1];
                for (int i=1; i<cmds.length; i++) newCmds[i+1] = cmds[i];
                newCmds[0] = cmds[0].substring(0,1);
                newCmds[1] = cmds[0].substring(1);
                cmds = newCmds;
            }
        }
        return cmds;
    }

    public static void displayHelp() {
        println("\nThis program lets you manipulate a small int array using");
        println("keyboard commands. Commands may be entered in either");
        println("upper or lower case. Put spaces between commands and values");
        println("if values are involved. All values must be integers.");
        println("The available commands are:\n");
        println("exit, x, quit, q: quit the program");
        println("print, p: display the contents of the array");
        println("status, stat, s: display stats about the array");
        println("help, h: display program help");
        println("find, f, ?: a value must follow the command; finds");
        println("      an element with that value");
        println("add, a, +: a value must follow the command; adds the");
        println("      value as the new last element if room is available");
        println("delete, del, d, -: a value must follow the command; deletes");
        println("      element with that value");
        println("delete_at, deleteat: an index must follow the command; deletes");
        println("      the element at that position in the array");
    }

    public static void displayStatus(OrderedArray a) {
        println("Status: size = " + a.size + ", number of elements = " + a.numElements);
    }
}

class OrderedArray {
    int[] arr;
    int numElements = 0;
    int size = 0;

    public OrderedArray() {
        this(10);
    }

    public OrderedArray(int n) {
        arr = new int[n];
        numElements = 0;
        size = n;
    }

    public void clear() {
        numElements = 0;
    }

    public int getElementAt(int pos) throws MyArrayException {
        if (pos < 0) throw new MyArrayException("Index out of bounds");
        else if (numElements <= pos) throw new MyArrayException("No element at position specified");
        return arr[pos];
    }

    public void deleteElementAt(int pos) throws MyArrayException {
        if (pos < 0) throw new MyArrayException("Index out of bounds");
        else if (numElements <= pos) throw new MyArrayException("No element at position specified");
        for (int i=pos; i<numElements-1; i++) arr[pos] = arr[pos+1];
        numElements--;
    }

    public boolean deleteElement(int val) {
        boolean found = false;
        for (int i=0; i<numElements; i++) {
            if (arr[i] == val) {
                for (int j=i; j<numElements-1; j++) {
                    arr[j] = arr[j+1];
                }
                numElements--;
                found = true;
                break;
            }
        }
        return found;
    }

    public void addElement(int val) throws MyArrayException {
        if (numElements >= size) throw new MyArrayException("Array full");
        else {
            arr[numElements++] = val;
            Arrays.sort(arr, 0, numElements);
        }
    }

    public int findElement(int val) {
        for (int i=0; i<numElements; i++)
            if (arr[i] == val) return i;
        return -1;
    }

    public void print() {
        for (int i=0; i<numElements; i++)
            System.out.print(Integer.toString(arr[i]) + "  ");
        System.out.println();
    }
}

class MyArrayException extends Exception {
    public MyArrayException() {}
    public MyArrayException(String msg) {
        super(msg);
    }
}