optionMethods.java

import java.util.Scanner;

public class optionMethods {

	private static String dp = "%.2f";
	/* Declaring the private global variable for decimal point precision and
	 initialising a default precision */
	double result, result2, squareroot, calculation;
	// Declaring the global variables used in both calculations

	public static void setdp(String decp) {
	// Creating the method for setting decimal point precision
		dp = decp;
	}

	public static String getdp() {
	// Creating the method for returning the decimal point precision
		return dp;
	}

	public void accuracy() {
	// Method for user to choose decimal point precision of equations in the program
		int a;
		Boolean validRange = false;
		// Creating Boolean variable to be used for do-while loop condition
		Scanner input = new Scanner(System.in);
		menu menu = new menu();

		try {
		// Creating try-catch block
			do {
			// Creating do-while loop
				System.out.print("Please enter an integer between 1-5 to determine the decimal point precision: ");
				a = input.nextInt();
				if(a>0 && a < 6) {
				// If statement used to validate user input against allowed range
					System.out.println();
					System.out.println("You have picked a decimal point precision of: " + a);
					String decimalplace = "%." + a + "f";
					setdp(decimalplace);
					// Creating precision for application depending on user input for 'a'
					validRange = true;
					// Condition set for do-while loop
				} 
				else {
				// Adding else statement if user has not input within allowed range
					System.out.println();
					System.out.println("ERROR - You need to pick a range between 1-5. Please press the enter key to try again.");
					menu.showNextStep();
					validRange = false;
					// Condition set for do-while loop
				}}
			while(!validRange);
		}
		catch (Exception e) {
		// Error message if user does not input an integer number for a
			System.out.println();
			System.out.println("ERROR - Invalid Entry. You must enter an integer number.");
		}
	}

	public void equation() {
	// method solve quadratic equation depending on user input
		float a, b, c;

		Scanner input = new Scanner(System.in);
		menu menu = new menu();
		System.out.println("The quadratic equation is ax^2 + bx + c = 0");
		// Quadratic equation syntax
		menu.showNextStep();
		// user input for float; a,b,c
		System.out.println("Please now pick the integer values you would like for the equation.");
		menu.showNextStep();

		try {
		// Creating try-catch block
			System.out.print("Integer a: ");
			a = input.nextFloat();
			System.out.print("Integer b: ");
			b = input.nextFloat();
			System.out.print("Integer c: ");
			c = input.nextFloat();

			// Calculations to work out quadratic equation
			calculation = (b * b) - (4 * a * c);
			squareroot = Math.sqrt(calculation);
			result = ((-b) + squareroot) / (2 * a);
			result2 = ((-b) - squareroot) / (2 * a);

			// Converting float a,b,c to int for equation printing.
			int a2 = Math.round(a);
			int b2 = Math.round(b);
			int c2 = Math.round(c);

			// printing the equation with user values, followed by result
			System.out.println();
			System.out.println("Given your values: " + a2 + "x^2 + " + b2 + "x + " + c2 + " =0");
			menu.showNextStep();

			String precision = getdp();
			// Calling the static method to declare new variable precision based on input
			// for dp from option 1
			System.out.println("x = " + String.format(precision, result));
			System.out.println("x = " + String.format(precision, result2));
		}

		catch (Exception e) {
		// Error message if user does not input numbers for variables a,b,c
			System.out.println();
			System.out.println("ERROR - Invalid Entry. You must enter an integer number.");
		}
	}

	public void linerEquation() {
	// Method for linear equation option
		float a, b, c;

		Scanner input = new Scanner(System.in);
		menu menu = new menu();
		System.out.println("The linear equation is ax + b = c");
		// Linear equation syntax
		menu.showNextStep();

		// user input for float; a,b,c
		System.out.println("Please now pick the integer values you would like for the equation.");
		menu.showNextStep();

		try {
		// Creating try-catch block
			System.out.print("Integer a: ");
			a = input.nextFloat();
			System.out.print("Integer b: ");
			b = input.nextFloat();
			System.out.print("Integer c: ");
			c = input.nextFloat();

			result = (c - b) / a;

			// Converting float a,b,c to int for equation printing.
			int a2 = Math.round(a);
			int b2 = Math.round(b);
			int c2 = Math.round(c);

			// printing the equation with user values, followed by result
			System.out.println();
			System.out.println("Given your values: " + a2 + "x + " + b2 + " = " + c2);
			menu.showNextStep();
			String precision = getdp();
			/* Calling the static method to declare new variable precision based on input
			for dp from Accuracy method */
			System.out.println("x = " + String.format(precision, result));
		}

		catch (Exception e) {
		// Error message if user does not input numbers for variables a,b,c
			System.out.println();
			System.out.println("ERROR - Invalid Entry. You must enter an integer number.");
		}
	}

	public void bubblesort() {
	// Using the bubblesort method to sort the user input for Student ID number
		menu menu = new menu();
		Scanner input = new Scanner(System.in);
		// Scanner input for user ID number
		String studentnumber;

		System.out.println("Please enter your 7 digit student ID when prompted!");
		// using e1 so variable does not clash with catch statement
		menu.showNextStep();

		try {
		// Creating try-catch block
			Boolean validID = false;
			// Declaring boolean validID for the do-while loop

			do {
			// Creating do while loop to validate student ID number inputed by user
				System.out.print("Enter your student ID number here; ");
				studentnumber = input.nextLine();
				// User to input their Student ID number
				int s;

				for(s=0; s < studentnumber.length(); s++) {
					// For loop used to create variable s for each entered digit by user
					if (Character.isLetter(studentnumber.charAt(s))) {
						// Creating if statement to validate whether user has inputed letters
						validID = false;
						// Creating condition for do-while loop to validate Student ID number length
						System.out.println();
						System.out.println("Error - this is not a valid Student ID, please press the enter key to try again.");
						menu.showNextStep();
						break;
						// Break used to terminate loop if condition is true

					} else
						validID = true;
						// Condition for else statement for do-while loop
				}
			} while (!validID);
			// loop condition for if-else statement to validate Student ID number 

			long sNumber = Long.parseLong(studentnumber);
			/* Converting 'studentnumber' to long 'sNumber' to validate user input 
			 against try-catch block for special characters. 
			 sNumber variable has no other use in the method */

			System.out.println();
			System.out.print("Your Student ID is: ");
			// Printing inputed student ID number to the console
			int studentID[] = new int[studentnumber.length()];
			// Creating array 'studentID' for numbers inputed by user
			for (int n = 0; n < studentID.length; n++) {
				studentID[n] = Character.getNumericValue(studentnumber.charAt(n));
				System.out.print(studentID[n]);
				// for loop used to obtain individual digits from user string input
			}
			System.out.println();
			System.out.println();
			bubblesort.bubblesort(studentID);
			// Calling the static bubble-sort method to be used for user input
			System.out.println("Please press enter to bubble sort your Student ID number!");
			menu.showNextStep();
			System.out.print("Your Student ID after the Bubble Sort is; ");
			// Printing bubble-sorted student ID number using array

			for (int i : studentID) {
			// Enhanced For loop used to call sorted ID numbers using index
				System.out.print(i);
			}
			System.out.println();	
		} catch (Exception e) {
		/* Error message if user does not input integer values for Student ID, returning
		user to main menu */
			System.out.println();
			System.out.println("ERROR - Invalid Entry. You must enter an integer number.");
		}
	}

	public void seconds() {
	// User to input int a - amount of seconds
		Scanner input = new Scanner(System.in);
		int a;

		try {
		// Creating try-catch block
			System.out.print("Enter a number of seconds: ");
			a = input.nextInt();
			System.out.println();
			// calculations to convert seconds into hours, minutes, seconds
			int hours = a / 3600;
			int remainder = a % 3600;
			int minutes = remainder / 60;
			int seconds = remainder % 60;
			System.out.println(a + " Seconds = " + hours + " hours " + minutes + " minutes " + seconds + " seconds ");
			// Printing the result
		} catch (Exception e) {
		// Error message if user does not input numbers for variables a,b,c
			System.out.println();
			System.out.println("ERROR - Invalid Entry. You must enter an integer number.");
		}
	}

	public void exit() {
	// Menu program exit method
		menu menu = new menu();
		System.out.println("Thank you for using my program today.");
		menu.showNextStep();
		System.exit(0);
	}
	
}