Question

The following pseudo-code describes a menu-driven algorithm:

loop
ask the user to input one of the characters a, b, c, d, e, q read in a character from the keyboard
if the character is

'a' output your name and your tutor's name (hard-coded) 'b' input 3 double numbers x, y, z and output the largest

and the smallest of the three numbers
'c' input 2 integer numbers m and n, and display all the

numbers between m and n (both inclusive) with five numbers per line (note that the last line may have less than 5 numbers). At the end, display the sum of all the odd numbers between m and n (both inclusive)

'd' input 3 integer numbers representing the sides of a triangle and display the numbers together with a message indicating whether or not the numbers form a triangle (Note: for the numbers to form a triangle, the sum of any two sides must be greater than the third side)

'e' input an integer number n and determine whether or not n is a prime number (Note: a number is a prime number if it is greater than 1 and has no divisors other than
1 and itself)

'q' exit from the loop

other: output an error message end if

end loop

1. Implement the above pseudo-code in a Java program using a while loop and a switch-case statement. The program should be well structured, and the task performed under each option (at least options 'b' to 'e') should be implemented as a separate method.

NOTE: The Scanner class does not have a method to input a character. In order to read a character from the keyboard, use one of the following methods (after declaring the Scanner object):

static Scanner sc = new Scanner(System.in);

1. char ch = sc.nextLine().charAt(0); OR
2. char ch = sc.nextLine().toLowerCase().charAt(0);

where sc is a Scanner class object.

The second method above also converts the input to lowercase, which is often useful. Though these methods allow the user to input more than one character on the input line, the rest of the line (after capturing the first character withcharAt(0)) is discarded.

If you also want to ignore the leading spaces before the first character then use:

1. char ch = sc.nextLine().trim().charAt(0); OR
2. char ch = sc.nextLine().trim().toLowerCase().charAt(0);

2. Write a program to extend question 1, by adding an option 'f' to your menu program. If this option is chosen, the program should ask the user to enter 10 integers. The program should store each integer into an array (as each one is entered). Once the array contains the 10 integers, the program should output: a) The sum of the 10 numbers entered

b) The average of the 10 numbers entered c) The highest number entered
d) The lowest number entered

3. Write a program that gets a string from the user and reports whether or not there are repeated characters in it.

4. Write a program that gets a string from the user and swaps the first and last characters.

Answer 1

/*

 * Question #1

*/

 

import java.util.*;

 

public class Menu {

         

        public static int largest(int x, int y, int z) {

                int large = x;

                if(x >= y && x >= z)

                        large = x;

                else if(y>=x && y >=z)

                        large = y;

                else

                        large = z;

                return large;           

        }

         

        public static int smallest(int x, int y, int z) {

                int small = x;

                if(x <= y && x <= z)

                        small = x;

                else if(y<=x && y <=z)

                        small = y;

                else

                        small = z;

                return small;           

        }

         

        public static void largeSmall() {

                Scanner sc = new Scanner(System.in);

                System.out.print("Enter three numbers: ");

                int x = sc.nextInt();

                int y = sc.nextInt();

                int z = sc.nextInt();

                System.out.println("Largest Number is " + largest(x,y,z));

                System.out.println("Smallest Number is " + smallest(x,y,z));

        }

         

        public static void numList() {

                Scanner sc = new Scanner(System.in);

                System.out.print("Enter two numbers: ");

                int m = sc.nextInt();

                int n = sc.nextInt();

                int count = 0;

                int sumOdd = 0;

                int i;

                for(i=m; i<=n; ++i) {

                        System.out.print(i + " ");

                        ++count;

                        if(count==5) {

                                System.out.println();

                                count = 0;

                        }

                        if(i%2 != 0)

                                sumOdd = sumOdd + i;

                }

                System.out.println();

                System.out.println("Sum of odd numbers between " + m + " and " + n + " is " + sumOdd);

        }

         

        public static void isTriangle() {

                Scanner sc = new Scanner(System.in);

                System.out.print("Enter three sides of triangle: ");

                int a = sc.nextInt();

                int b = sc.nextInt();

                int c = sc.nextInt();

                String res = "";

                if(!((a+b) > c && (b+c) > a && (a+c) > b))

                        res = "not";

                System.out.println("The three sides " + a + ", " + b + ", " + c + " can" + res + " form a triangle");

        }

         

        public static void isPrime() {

                Scanner sc = new Scanner(System.in);

                System.out.print("Enter a number: ");

                int n = sc.nextInt();

                int i;

                boolean prime = true;

                if(n<2)

                        prime = false;

                else {

                        for(i=2; i<(n/2); ++i) {

                                if(n%i == 0) {

                                        prime = false;

                                        break;

                                }

                        }

                }

                if(prime)

                        System.out.println(n + " is a Prime number");

                else

                        System.out.println(n + " is not a Prime number");

        }

         

        public static void arrayNum() {

                Scanner sc = new Scanner(System.in);

                System.out.print("Enter ten numbers: ");

                int a[] = new int[10];

                int i;

                int sum = 0;

                double avg = 0.0;

                int max, min;

                 

                for(i=0; i<10; ++i)

                        a[i] = sc.nextInt();

                         

                max = min = a[0];

                for(i=0; i<10; ++i) {

                        sum = sum + a[i];

                        if(a[i] > max)

                                max = a[i];

                        if(a[i] < min)

                                min = a[i];

                }

                         

                avg = sum/10.0;

                System.out.println("Sum of the 10 numbers is " + sum);

                System.out.println("Average of the 10 numbers is " + avg);

                System.out.println("Highest Number is " + max);

                System.out.println("Lowest Number is " + min);

        }

         

    public static void main(String[] args) {

         

        Scanner sc = new Scanner(System.in);

        char ch;

        loop:

        do {                    

                System.out.print("Enter a character: ");

                ch = sc.next().toLowerCase().trim().charAt(0);

                switch(ch) {

                        case 'a':

                                System.out.println("MyName");           //Replace MyName with your name

                                System.out.println("TutorName");        //Replace MyName with your tutor's name

                                break;

                        case 'b':

                                largeSmall();

                                break;

                        case 'c':

                                numList();

                                break;

                        case 'd':

                                isTriangle();

                                break;

                        case 'e':

                                isPrime();

                                break;

                        case 'f':

                                arrayNum();

                                break;

                        case 'q':

                                break loop;

                        default:

                                System.out.println("Invalid     Character. Please re-try OR type 'q' to exit");

                                break;

                }               

         }while(ch!='q');  

                  

    }  

     

}

 

 

/*

 * Question #2

*/

 

import java.util.*;

 

public class RepeatChar {

 

    public static void main(String []args) {

         

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter a String: ");

        String s = sc.nextLine();

        int i;

        char ch;

        String res = "does not have";

        for(i=0; i< s.length(); ++i) {

                ch = s.charAt(i);

                if(s.indexOf(ch) != s.lastIndexOf(ch)) {

                        res = "has";

                }                       

        }

        System.out.println("String " + res + " repeated characters");

         

    }

     

}

 

 

/*

 * Question #3

*/

 

import java.util.*;

 

public class SwapChar {

 

   public static void main(String []srgs) {

         

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter a String: ");

        String s = sc.nextLine();

        int i;

        int l = s.length();

        String swap = "";

        swap = swap + s.charAt(l-1);

        for(i=1; i<l-1; ++i) {

            swap = swap + s.charAt(i);

        }

        swap = swap + s.charAt(0);

        System.out.println("String after swapping first and last character is " + swap);

         

    }

     

}