Java || Find The Prime, Perfect & All Known Divisors Of A Number Using A For, While & Do/While Loop

June 24, 2012 admin No comments

This program was designed to better understand how to use different loops which are available in Java, as well as more practice using objects with classes.

This program first asks the user to enter a non negative number. After it obtains a non negative integer from the user, the program determines if the user obtained number is a prime number or not, aswell as determining if the user obtained number is a perfect number or not. After it obtains its results, the program will display to the screen if the user inputted number is prime/perfect number or not. The program will also display a list of all the possible divisors of the user obtained number via stdout.

REQUIRED KNOWLEDGE FOR THIS PROGRAM

Class Objects - How TO Use Constructors - What Are They? Do/While Loop While Loop For Loop Modulus Basic Math - Prime Numbers Basic Math - Perfect Numbers Basic Math - Divisors





		
		
			Is It Prime or Perfect? List All Possible Divisors
			
Java
			
			import java.util.Scanner;

public class PrimePerfectNums
{
	// global variable declaration
	int userInput = 0;	
	static Scanner cin = new Scanner(System.in);
	
	public PrimePerfectNums(int input)
	{// this is the constructor
		// give the global variable a value
		userInput = input;

	}// end of PrimePerfectNums
	
	public void CalcPrimePerfect() 
	{
		// declare variables
		int divisor = 0;
		int sumOfDivisors = 0;		
		
		System.out.print("nInput number: " + userInput);
		
		// for loop adds sum of all possible divisors
		for(int counter=1; counter <= userInput; ++counter)
		{
			divisor = (userInput % counter);
			if(divisor == 0)
			{
				// this will repeatedly add the found divisors together
				sumOfDivisors += counter;
			}
		}
		
		System.out.println("");
		// uses the 'sumOfDivisors' variable from ^ above for loop to
		// check if 'userInput' is prime
		if(userInput == (sumOfDivisors - 1))
		{
			System.out.print(userInput + " is a prime number.");
		}
		else
		{
			System.out.print(userInput + " is not a prime number.");
		}
		
		System.out.println("");
		// uses the 'sumOfDivisors' variable from ^ above for loop to
		// check if 'userInput' is a perfect number
		if (userInput == (sumOfDivisors - userInput))
		{
			System.out.print(userInput + " is a perfect number.");
		}
		else
		{
			System.out.print(userInput + " is not a perfect number.");
		}
		
		System.out.print("nDivisors of " + userInput + " are: ");
		// for loop lists all the possible divisors for the
		// 'userInput' variable by using the modulus operator
		for(int counter=1; counter <= userInput; ++counter)
		{
			divisor = (userInput % counter);
			if(divisor == 0 && counter !=userInput)
			{
				System.out.print(counter + ", ");
			}
		}
		
		System.out.print("and " + userInput);					
	}// end of CalcPrimePerfect
	
	public static void main(String[] args)
	{
		// declare variables
		int input = 0;
		char response ='n';
		
		do{ // this is the start of the do/while loop
			
			System.out.print("Enter a number: ");
			input = cin.nextInt();
			
			// if the user inputs a negative number, do this code
			while(input < 0) 
			{
				System.out.print("ntSorry, but the number entered is less " +
						"than the allowable limit.ntPlease try again.....");
				System.out.print("nnEnter an number: ");
				input = cin.nextInt();
			}
			// entry point to class declaration
			PrimePerfectNums myClass = new PrimePerfectNums(input);
			
			// function call to obtain data using the number
			// which was passed from main to the constructor
			myClass.CalcPrimePerfect();
			
			// asks user if they want to enter new data
			System.out.print("nntDo you want to input another number?(Y/N): ");
			response = cin.next().toLowerCase().charAt(0);
			
			System.out.println("---------------------------" +
				"---------------------------------");		
		}while(response =='y');
		// ^ End of the do/while loop. As long as the user chooses
		// 'Y' the loop will keep going.
		// It stops when the user chooses the letter 'N'
		
		System.out.println("BYE!");		
	}// end of main	
}// http://programmingnotes.org/
			
				
					
				
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						import java.util.Scanner;
 
public class PrimePerfectNums
{
	// global variable declaration
	int userInput = 0;	
	static Scanner cin = new Scanner(System.in);
	
	public PrimePerfectNums(int input)
	{// this is the constructor
		// give the global variable a value
		userInput = input;
 
	}// end of PrimePerfectNums
	
	public void CalcPrimePerfect() 
	{
		// declare variables
		int divisor = 0;
		int sumOfDivisors = 0;		
		
		System.out.print("nInput number: " + userInput);
		
		// for loop adds sum of all possible divisors
		for(int counter=1; counter <= userInput; ++counter)
		{
			divisor = (userInput % counter);
			if(divisor == 0)
			{
				// this will repeatedly add the found divisors together
				sumOfDivisors += counter;
			}
		}
		
		System.out.println("");
		// uses the 'sumOfDivisors' variable from ^ above for loop to
		// check if 'userInput' is prime
		if(userInput == (sumOfDivisors - 1))
		{
			System.out.print(userInput + " is a prime number.");
		}
		else
		{
			System.out.print(userInput + " is not a prime number.");
		}
		
		System.out.println("");
		// uses the 'sumOfDivisors' variable from ^ above for loop to
		// check if 'userInput' is a perfect number
		if (userInput == (sumOfDivisors - userInput))
		{
			System.out.print(userInput + " is a perfect number.");
		}
		else
		{
			System.out.print(userInput + " is not a perfect number.");
		}
		
		System.out.print("nDivisors of " + userInput + " are: ");
		// for loop lists all the possible divisors for the
		// 'userInput' variable by using the modulus operator
		for(int counter=1; counter <= userInput; ++counter)
		{
			divisor = (userInput % counter);
			if(divisor == 0 && counter !=userInput)
			{
				System.out.print(counter + ", ");
			}
		}
		
		System.out.print("and " + userInput);					
	}// end of CalcPrimePerfect
	
	public static void main(String[] args)
	{
		// declare variables
		int input = 0;
		char response ='n';
		
		do{ // this is the start of the do/while loop
			
			System.out.print("Enter a number: ");
			input = cin.nextInt();
			
			// if the user inputs a negative number, do this code
			while(input < 0) 
			{
				System.out.print("ntSorry, but the number entered is less " +
						"than the allowable limit.ntPlease try again.....");
				System.out.print("nnEnter an number: ");
				input = cin.nextInt();
			}
			// entry point to class declaration
			PrimePerfectNums myClass = new PrimePerfectNums(input);
			
			// function call to obtain data using the number
			// which was passed from main to the constructor
			myClass.CalcPrimePerfect();
			
			// asks user if they want to enter new data
			System.out.print("nntDo you want to input another number?(Y/N): ");
			response = cin.next().toLowerCase().charAt(0);
			
			System.out.println("---------------------------" +
				"---------------------------------");		
		}while(response =='y');
		// ^ End of the do/while loop. As long as the user chooses
		// 'Y' the loop will keep going.
		// It stops when the user chooses the letter 'N'
		
		System.out.println("BYE!");		
	}// end of main	
}// http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

Once compiled, you should get this as your output:

Enter a number: 41
Input number: 41 41 is a prime number. 41 is not a perfect number. Divisors of 41 are: 1, and 41 Do you want to input another number?(Y/N): y ------------------------------------------------------------ Enter a number: 496 Input number: 496 496 is not a prime number. 496 is a perfect number. Divisors of 496 are: 1, 2, 4, 8, 16, 31, 62, 124, 248, and 496 Do you want to input another number?(Y/N): y ------------------------------------------------------------ Enter a number: 1858 Input number: 1858 1858 is not a prime number. 1858 is not a perfect number. Divisors of 1858 are: 1, 2, 929, and 1858 Do you want to input another number?(Y/N): y ------------------------------------------------------------ Enter a number: -9 Sorry, but the number entered is less than the allowable limit. Please try again..... Enter an number: 12 Input number: 12 12 is not a prime number. 12 is not a perfect number. Divisors of 12 are: 1, 2, 3, 4, 6, and 12
Do you want to input another number?(Y/N): n ------------------------------------------------------------ BYE!

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Java || Find The Prime, Perfect & All Known Divisors Of A Number Using A For, While & Do/While Loop

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