menu.java

Linked List implementation for education purposes.

// menu class displays a menu of choices to a user
//               and performs the chosen task. It will keep asking a user to
//               enter the next choice until the choice of 'Q' (Quit) is
//               entered.

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class menu
{
    public static void main(String[] args)
    {
        char input1='\0';
        String inputInfo = new String();
        int operation2;
        String line = new String();

        //create a linked list to be used in this method.
        LinkedList list1 = new LinkedList();

        try
        {
            // print out the menu
            printMenu();

            // create a BufferedReader object to read input from a keyboard
            InputStreamReader isr = new InputStreamReader(System.in);
            BufferedReader stdin = new BufferedReader(isr);

            do
            {
                do
                {
                    System.out.print("What action would you like to perform?\n");
                    line = stdin.readLine().trim();  //read a line
                    if (line.length() > 0)
                    {
                        input1 = line.charAt(0);
                        input1 = Character.toUpperCase(input1);
                    }
                }
                while (line.length() == 0);

                if (line.length() == 1)   //check if a user entered only one character
                {
                    switch (input1)
                    {
                        case'A':   //Add String
                            System.out.print("Please enter a string to add:\n");
                            String str1 = stdin.readLine().trim();
                            System.out.print("Please enter an index to add:\n");
                            inputInfo = stdin.readLine().trim();
                            int addIndex = Integer.parseInt(inputInfo);
                            list1.addElement(addIndex, str1);
                            break;
                        case'D':   //Search for the Index of a String
                            System.out.print("Please enter a string to search:\n");
                            inputInfo = stdin.readLine().trim();
                            operation2 = list1.searchElement(inputInfo);
                            if (operation2 > -1)
                                System.out.print("string found at " + operation2 + "\n");
                            else
                                System.out.print("string not found\n");
                            break;
                        case'L':   //List Strings
                            System.out.print(list1.toString());
                            break;
                        case'O':  // List Current Size
                            System.out.print("The current size is " + list1.size() + "\n");
                            break;
                        case'Q':   //Quit
                            break;
                        case'R':  //Remove String
                            System.out.print("Please enter the index of a string to remove:\n");
                            inputInfo = stdin.readLine().trim();
                            int removeIndex = Integer.parseInt(inputInfo);
                            System.out.println(list1.removeElement(removeIndex) + " was removed");
                            break;
                        case'T':   //Find the smallest
                            if (!list1.isEmpty())
                                System.out.print("The smallest is: " + list1.findSmallest() + "\n");
                            else
                                System.out.print("The list is empty\n");
                            break;
                        case'U':   //Remove all the occurence of a given string
                            System.out.print("Please enter a string to remove:\n");
                            inputInfo = stdin.readLine().trim();
                            int index = list1.searchElement(inputInfo);
                            if (index > -1)
                            {
                                list1.removeAllOccurrences(inputInfo);
                                System.out.print("All occurences of " + inputInfo + " removed\n");
                            }
                            else
                                System.out.print("string not found\n");
                            break;
                        case'?':   //Display Menu
                            printMenu();
                            break;
                        default:
                            System.out.print("Unknown action\n");
                            break;
                    }
                }
                else
                {
                    System.out.print("Unknown action\n");
                }
            }
            while (input1 != 'Q' || line.length() != 1);
        }
        catch (IOException exception)
        {
            System.out.print("IO Exception\n");
        }
    }

    /**
     * The method printMenu displays the menu to a user *
     */
    public static void printMenu()
    {
        System.out.print(
                "Choice\t\tAction\n" + "------\t\t------\n" + "A\t\tAdd String\n" + "D\t\tSearch for Index\n" + "L\t\tList Strings\n" + "O\t\tList Current Size\n" + "Q\t\tQuit\n" + "R\t\tRemove String\n" + "T\t\tFind Smallest\n" + "U\t\tRemove All Occurrences\n" + "?\t\tDisplay Help\n\n");
    } //end of printMenu()
}