Need help with a java project I need to do. Here is the project specifications :

"""Create a console calculator applicaion that:
* Takes one command line argument: your name and surname. When the
program starts, display the date and time with a welcome message for the
user.
* Display all the available options to the user. Your calculator must include
the arithmetic operations as well as at least five scientific operations of the
Math class.
-Your program must also have the ability to round a number and
truncate it.
-When you multiply by 2, you should not use the '*' operator to perform the
operation.
-Your program must also be able to reverse the sign of a number.
* Include sufficient error checking in your program to ensure that the user
only enters valid input. Make use of the String; Character, and other
wrapper classes to help you.
* Your program must be able to do conversions between decimal, octal and
hex numbers.
* Make use of a menu. You should give the user the option to end the
program when entering a certain option.
* When the program exits, display a message for the user, stating the
current time, and calculate and display how long the user used your
program.
* Make use of helper classes where possible.
* Use the SDK to run your program."""

I am stuck at the moment and don't know how to correct this problem.

I have created a method ' hexadecimalEquivalent(); ' (among others...) which if the user chooses, it converts the numbers he/she provided as input to the hexadecimal equivalent, my ' octalEquivalent(); ' method works but I get an error message with my ' hexadecimalEquivalent(); ' method and it states
" Exception in thread "main" java.lang.NumberFormatException: For input string: "b"
at java.lang.NumberFormatException.forInputString(Unknown Source)
at java.lang.Long.parseLong(Unknown Source)
at java.lang.Long.parseLong(Unknown Source)
at org.Java.Instructor.Project.hexadecimalEquivalent1(Project.java:86)
at org.Java.Instructor.Project.Calculator(Project.java:271)
at org.Java.Instructor.Project.main(Project.java:329)
"

Can anyone please help me.

Here is the code that I have done so far for my Project.class:

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

public class Project {
	
	
	private static String nameSurname = "";	
	private static String num1 = null; 
	private static String num2 = null; 
	private static String choice1 = null;
	private static double answer = 0;
	private static char more;
	
	public double Add() {
		answer = (Double.parseDouble(num1) + Double.parseDouble(num2));
		return answer;
	}
	
	public double Subtract() {
		answer = (Double.parseDouble(num1) - Double.parseDouble(num2));
		return answer;
	}
	
	public double Multiply() {
		answer = (Double.parseDouble(num1) * Double.parseDouble(num2));
		return answer;
	}
	
	public double Divide() {
		answer = (Double.parseDouble(num1) / Double.parseDouble(num2));
		return answer;
	}
	
	public double Modulus() {
		answer = (Double.parseDouble(num1) % Double.parseDouble(num2));
		return answer;
	}
	
	public double maximumValue() {
		answer = (Math.max(Double.parseDouble(num1), Double.parseDouble(num2)));
		return answer;
	}
	
	public double minimumValue() {
		answer = (Math.min(Double.parseDouble(num1), Double.parseDouble(num2)));
		return answer;
	}
	
	public double absoluteNumber1() {
		answer = (Math.abs(Double.parseDouble(num1)));
		return answer;
	}
	
	public double absoluteNumber2() {
		answer = (Math.abs(Double.parseDouble(num2)));
		return answer;
	}
	
	public double Squareroot1() {
		answer = (Math.sqrt(Double.parseDouble(num1)));
		return answer;
	}
	
	public double Squareroot2() {
		answer = (Math.sqrt(Double.parseDouble(num2)));
		return answer;
	}
	
	public double octalEquivalent1() {
		long n1 = Long.parseLong(num1);
		answer = Long.parseLong(Long.toOctalString(n1));
		return answer;
	}
	
	public double octalEquivalent2() {
		long n2 = Long.parseLong(num2);
		answer = Long.parseLong(Long.toHexString(n2));
		return answer;
	}
	
	public double hexadecimalEquivalent1() {
		long n1 = Long.parseLong(num1);
		answer = Long.parseLong(Long.toHexString(n1));
		return answer;
	}
	
	public double hexadecimalEquivalent2() {
		long n2 = Long.parseLong(num2);
		answer = Long.parseLong(Long.toHexString(n2));
		return answer;
	}
	
	public double Round1() {
		answer = Math.round(Double.parseDouble(num1));
		return answer;
	}
	
	public double Round2() {
		answer = Math.round(Double.parseDouble(num2));
		return answer;
	}
	
	
		SimpleDateFormat format1 = new SimpleDateFormat("EEEE, dd MMMM yyyy");
	    Date now = new Date();
	    
	    SimpleDateFormat format2 = new SimpleDateFormat("hh:mm a");
	    Date now2 = new Date();
	    
	    DecimalFormat decimals = new DecimalFormat("#0.00");
	    
	    

	    
	    public String insertNameAndSurname() throws IOException{
	    	boolean inputCorrect = false;
	    		while (inputCorrect == false) {
	    			while (nameSurname == null || nameSurname.length() == 0) {
	    				
	    				for (int i = 0; i < nameSurname.length(); i++) {
	    				    if ((nameSurname.charAt(i) > 'a') && (nameSurname.charAt(i) < 'Z')){
	    				    		inputCorrect = true;
	    			           }
	    			            else{
	    			                    inputCorrect = false;
	    			                    break;
	    			             }
	    			}
	    				
	    			try {
	    				BufferedReader inStream = new BufferedReader (new InputStreamReader(System.in));
	    				System.out.print("Please enter your name and surname: ");
	    				nameSurname = inStream.readLine();
	    				inputCorrect = true;
	    			}catch (IOException ex) {
	    				System.out.println("You did not enter your name and surname, " + nameSurname + " is not a name, please enter your name and surname :");
	    				inputCorrect = false;
	    			}
	    			}
	    			System.out.println("\nA warm welcome " + nameSurname + " ,todays date is: " + format1.format(now));
    				System.out.println("and the time is now exactly " + format2.format(now2) + ".");
	    		}
				return nameSurname;
	    }
			
	    	 

		public String inputNumber1() throws IOException {
	    	boolean inputCorrect = false;
	    		while (inputCorrect == false) {
	    			try {
	    				BufferedReader br = new BufferedReader (new InputStreamReader(System.in));
	    				System.out.print("\nPlease enter a number you want to do a calculation with and hit <ENTER>: ");
	    				num1 = br.readLine();
	    				double number1 = Double.parseDouble(num1);
	    				System.out.println("\nThe number you have entered is: " + number1);
	    				inputCorrect = true;
	    			} catch (NumberFormatException nfe) {
	    				System.out.println("\nYou did not enter a valid number:  " + "\""+ num1 + "\"  is not a number!!");
	    				inputCorrect = false;
	    			} 
	    		}
				return num1;
	    }
		
	    
	    public String calculatorChoice() throws IOException {
	    	System.out.println("Please select an option of what you would like to do with this number from the menu below and hit <ENTER>: ");
	    
	    	System.out.println("\n*********************************************");
	    	System.out.println("---------------------------------------------");
	    	System.out.println("Please select an option from the list below: ");
	    	System.out.println("---------------------------------------------");
	    	System.out.println("1 - Add");
	    	System.out.println("2 - Subtract");
	    	System.out.println("3 - Multiply");
	    	System.out.println("4 - Divide (remainder included)");
	    	System.out.println("5 - Maximum and minimum value of two numbers");
	    	System.out.println("6 - Squareroot");
	    	System.out.println("7 - Absolute value of numbers");
	    	System.out.println("8 - Octal and Hexadecimal equivalent of numbers");
	    	System.out.println("9 - Round numbers");
	    	System.out.println("0 - Exit program");
	    	System.out.println("**********************************************");
	    	
	    	boolean inputCorrect = false;
	    		while (inputCorrect == false) {
	    			try {
	    				BufferedReader inStream = new BufferedReader (new InputStreamReader(System.in));
	    				System.out.print("Please enter your option and hit <ENTER>: ");
	    				choice1 = inStream.readLine();
	    				int c1 = Integer.parseInt(choice1);
	    				System.out.println("\nYou have entered choice number: " + c1);
	    				inputCorrect = true;
	    			} catch (NumberFormatException nfe) {
	    				System.out.println("You did not enter a valid  choice number:  " + "\""+ choice1 + "\"  is not in the list!!");
	    				inputCorrect = false;
	    			} 
	    		}
				return choice1;
	    }
	    
	    
	    public String inputNumber2() throws IOException {
	    	boolean inputCorrect = false;
	    		while (inputCorrect == false) {
	    			try {
	    				BufferedReader br2 = new BufferedReader (new InputStreamReader(System.in));
	    				System.out.print("\nPlease enter another number you want to do the calculation with and hit <ENTER>: ");
	    				num2 = br2.readLine();
	    				double n2 = Double.parseDouble(num2);
	    				System.out.println("\nThe second number you have entered is: " + n2);
	    				System.out.println("\nYour numbers are: " + num1 + " and " + num2);
	    				inputCorrect = true;
	    			} catch (NumberFormatException nfe) {
	    				System.out.println("You did not enter a valid number:  " + "\""+ num2 + "\"  is not a number!!");
	    				inputCorrect = false;
	    			} 	
	    		}
				return num2;
	    }
	    
	    
	    public int Calculator() {
	    	int choice2 = (int) Double.parseDouble(choice1);
	    	switch (choice2) {
				case 1 :
					Add();
					System.out.print("The answer of " + num1 + " + "  + num2 + " is: " + decimals.format(answer));
					break;
				case 2 :
					Subtract();
					System.out.print("The answer of " + num1 + " - " + num2 + " is: " + decimals.format(answer));
					break;
				case 3 :
					Multiply();
					System.out.print("The answer of " + num1 + " * " + num2 + " is: " + decimals.format(answer));
					break;
				case 4 :
					Divide();
					System.out.print("The answer of " + num1 + " / " + num2 + " is: " + decimals.format(answer));
					Modulus();
					System.out.print(" and the remainder is "  + decimals.format(answer));
					break;
				case 5 :
					maximumValue();
					System.out.println("The maximum number between the numbers " + num1 + " and " + num2 + " is: " + decimals.format(answer));
					minimumValue();
					System.out.println("The minimum number between the numbers " + num1 + " and " + num2 + " is: " + decimals.format(answer));
					break;
				case 6 :
					Squareroot1();
					System.out.println("The squareroot of value " + num1 + " is: " + decimals.format(answer));
					Squareroot2();
					System.out.println("The squareroot of value " + num2 + " is: " + decimals.format(answer));
					break;
				case 7 :
					absoluteNumber1();
					System.out.println("The absolute number of " + num1 + " is: " + decimals.format(answer));
					absoluteNumber2();
					System.out.println("The absolute number of " + num2 + " is: " + decimals.format(answer));
					break;
				case 8 :
					octalEquivalent1();
					System.out.println("The octal equivalent of " + num1 + " is: " + decimals.format(answer));
					hexadecimalEquivalent1();
					System.out.println("The hexadecimal equivalent of " + num1 + " is: " + decimals.format(answer));
					octalEquivalent2();
					System.out.println("\nThe octal equivalent of " + num2 + " is: " + decimals.format(answer));
					hexadecimalEquivalent2();
					System.out.println("The hexadecimal equivalent of " + num2 + " is: " + decimals.format(answer));
					break;
				case 9 :
					Round1();
					System.out.println("The rounded number of " + num1 + " is: " + decimals.format(answer));
					Round2();
					System.out.println("The rounded number of " + num2 + " is: " + decimals.format(answer));
					break;
				case 0 :
					if (choice2 == 0) {
						System.exit(1);
					}
					break;
	    	}
			return choice2;
	    }
	    

		public char anotherCalculation() throws IOException {
	    	try {
	    	   	System.out.print("\nWould you like to do another calculation? Y/N");
	    	   	more = (char) System.in.read();
	    	   	do {
	    	   		inputNumber1();
	    	   		System.out.println("");
	    	   		calculatorChoice();
	    	   		System.out.println("");
	    	   		inputNumber2();
	    	   		System.out.println("");
	    	   		Calculator();
	    	   		System.out.println("");
	    	   		anotherCalculation();
	    			System.out.println("");
	    	   	} 	while((more == 'y') | (more == 'Y')); 
	    	   	System.exit(0);
	    	} catch (IOException ex){
	    		System.exit(0);
	    	}
			return more;
	    }
	    
	    
	    public static void main(String[] args) throws IOException {
	    	Project p1 = new Project();
	  
	    	p1.insertNameAndSurname();
	    	System.out.println("");
	    	p1.inputNumber1();
	    	System.out.println("");
	    	p1.calculatorChoice();
	    	System.out.println("");
	    	p1.inputNumber2();
	    	System.out.println("");
	    	p1.Calculator();
			System.out.println("");
			p1.anotherCalculation();
			System.out.println("");
			
	    }
}

Your help will be much appreciated.
Thanks

How is Long.toHexString working for octal ? where you are supposed to convert a string in hex format ?

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