Help Creating Java Program Menu, Classes, and Quit function

Question

I am creating a java program and I do not know how to put my 3 functions into it.

I also need some sort of menu screen and a way to quit the program.

These are my only guidelines:

 

• You must create separate class for the each function.
• There should be one class that contains the main method and that should also display the menu from where user can choose the options. So there should be total 4 java files.
• You must use proper naming convention for classes, objects, variables, etc.

 

Here are the 3 functions.

 

Programs 1 :


import java.util.Scanner;

class Factorial
{
public static void main(String args[])
{
int n, c, fact = 1;

System.out.println("Enter an integer to calculate it's factorial");
Scanner in = new Scanner(System.in);

n = in.nextInt();

if ( n < 0 )
System.out.println("Number should be non-negative.");
else
{
for ( c = 1 ; c <= n ; c++ )
fact = fact*c;

System.out.println("Factorial of "+n+" is = "+fact);
}
}
}

 

 

 

Program 2

import java.util.Scanner;

public class FibonacciSeries {

public static void main(String[] args) {
Scanner s = new Scanner(System.in);
System.out.print("Enter the value of n: ");
int n = s.nextInt();
fibonacci(n);
}

public static void fibonacci(int n) {
if (n == 0) {
System.out.println("0");
} else if (n == 1) {
System.out.println("0 1");
} else {
System.out.print("0 1 ");
int a = 0;
int b = 1;

 

 

Program 3:

 

 

import java.util.Scanner;

class MultiplicationTable
{
public static void main(String args[])
{
int n, c;
System.out.println("Enter an integer to print it's multiplication table");
Scanner in = new Scanner(System.in);
n = in.nextInt();
System.out.println("Multiplication table of "+n+" is :-");

for ( c = 1 ; c <= 10 ; c++ )
System.out.println(n+"*"+c+" = "+(n*c));
}
}

 

 

Answer 1

Make class Factorial as separate class file of its own that is passed and returns an integer. Create a new class file called Menu that contains main(). Its function should simply be to give the user the choice of 4 options: determine a factorial, print a Fibonacci sequence, create a multiplication table or quit. Use a switch to invoke the appropriate class function, quit or tell the user it's an invalid choice and put the whole thing in a while loop that runs until the user selects 'quit'. The rest of the class files should require minimal tweaking other than the factorial one (since it's now being invoked rather than part of main)

Answer 2

// User Interface Utilities

import java.io.*;

class UI_Util

{

private Console console;

UI_Util()

{

console = System.console();

}

public int Menu ( String [] menuOptions, String menuTitle)

{

String inbuff;

int user_menu_choice=-1;

int N = menuOptions.length;

if (menuTitle == null) { menuTitle = new String(" MAIN MENU"); }

while ((user_menu_choice<0) || (user_menu_choice>N))

{

System.out.println("*********************************************");

System.out.println(menuTitle);

System.out.println("*********************************************");

for (int iLoop=0; iLoop<N; iLoop++)

{

System.out.println(" <" + (iLoop+1) + "> " + menuOptions[iLoop]);

}

System.out.println("*********************************************");

System.out.println(" OR INPUT ZER0 to EXIT the menu ");

System.out.println("*********************************************");

System.out.print(" Please input your choice :> ");

inbuff = console.readLine();

user_menu_choice = Integer.parseInt(inbuff);

}

return(user_menu_choice);

}

public int PromptForInteger( String promptMsg)

{

String inbuff;

int iReturn;

System.out.println("******************************************************");

System.out.print(promptMsg + ":> ");

inbuff = console.readLine();

iReturn = Integer.parseInt(inbuff);

return(iReturn);

}

}

//Driver.java

class Driver

{

public int Go()

{

int iReturn = 0;

int n;

UI_Util myUI_Util = new UI_Util();

String[] menuOptions = {"FACTORIAL","FIBONACCI","MULTIPLICATION TABLE"};

int user_menu_choice = -1;

do

{

user_menu_choice = myUI_Util.Menu(menuOptions,"MAIN MENU");

System.out.println("\n\n\n");

switch (user_menu_choice)

{

case 0:

{

System.out.println(" Goodbye \n");

break;

}

case 1:

{

n=myUI_Util.PromptForInteger(" Please input the integer of which to calculate the factorial");

Factorial myFactorial = new Factorial();

System.out.println( n + "! = " + myFactorial.factorial(n));

break;

}

case 2:

{

n=myUI_Util.PromptForInteger(" Please input the integer of which to calculate the fibonacci");

Fibonacci myFibonacci = new Fibonacci();

for (int iLoop=1; iLoop<=n; iLoop++)

{

System.out.print(myFibonacci.fibonacci(iLoop) + " ");

}

break;

}

case 3:

{

n=myUI_Util.PromptForInteger(" Please input the integer of which to show the multiples");

MultiplicationTable myMultiplicationTable = new MultiplicationTable(10);

myMultiplicationTable.Go(n);

System.out.println("\n\n");

break;

}

} //switch

System.out.println("\n");

} //while

while (user_menu_choice != 0);

return iReturn;

} //Go

public static void main(String args[])

{

Driver myDriver = new Driver();

myDriver.Go();

}

}

//Factorial.java

class Factorial

{

// should check n for possible overflow error

int factorial( int n)

{

int iReturn;

if (n==0)

{

iReturn = 1;

}

else

{

iReturn = n * factorial(n-1);

}

return(iReturn);

}

}

//class MultiplicationTable.java

class MultiplicationTable

{

private int nMax;

MultiplicationTable( int maxN) { nMax = maxN; }

public void Go ( int x)

{

for (int iLoop=1; iLoop<=nMax; iLoop++)

{

System.out.print( (iLoop * x) + " ");

}

}

}

//Fibonacci.java

class Fibonacci

{

// should check n for possible overflow error

int fibonacci( int n)

{

int iReturn;

if ((n==0) || (n==1))

{

iReturn = 1;

}

else

{

iReturn = fibonacci(n-1) + fibonacci(n-2);

}

return(iReturn);

}

}