CODEWITHSUNDEEP
java
robert
robert

Reputation: 135

Java - array list to output all factors

I've been asked to create a method that returns all of the factors as an array list. Any help would be appreciated as I've been stuck for some while now.

/**
 * Determines whether the number has factors.
 * 
 * @return   true iff the number has a factor
 */
public boolean hasMoreFactors()
{
    if (number >= 2) {
        return true;
    } else {
        return false;
    }
    // return (number >= 2);
}

/**
 * Is number divisible by a given other number?
 * 
 * @param otherNumber the number we test whether it divides the object's number
 * @return true iff the number is divisible by otherNumber
 */
public boolean isDivisible(int otherNumber)
{
    if (number % otherNumber == 0) {
        return true; 
    } else {
        return false;
    }
}

/**
 * Determine next factor.
 * pre-condition: call only if hasMoreFactors 
 * returns true
 * 
 * @return a factor of the object's number
 */
public int nextFactor()
{
    int triedFactor = 2;
    while (! isDivisible(triedFactor)) {
        triedFactor = triedFactor+1;

    }
    number = number / triedFactor;
    return triedFactor;
}

/**
 * Print all factors of the generator's number on standard output.
 */
public void printAllFactors()
{
    System.out.println("Factors of " + number);
    while (hasMoreFactors()) {
        System.out.println(nextFactor());
    }
    System.out.println("That's it.");
}

 /**
 * Main method: Read an integer and print all its factors.
 */
public static void main(String[] args)
{
    System.out.print("Please enter a number greater or equal 2: ");
    Scanner sc = new Scanner(System.in);
    int num = sc.nextInt();
    System.out.println();
    FactorGenerator gen = new FactorGenerator(num);
    gen.printAllFactors();
}

}

Upvotes: -1

Views: 3196

Answers (2)

Ray
Ray

Reputation: 4869

It looks like what you missed it the case where a number has the same factor multiple times. For example, 4 = 2 * 2, but after you've tried 2, you increment and try 3 next. You need to keep trying each candidate until it is no longer a factor.

Upvotes: 0

dogbane
dogbane

Reputation: 274650

Instead of printing them out in this line:

System.out.println(nextFactor());

create an ArrayList:

List<Integer> list = new ArrayList<Integer>();

and store them in it:

list.add(nextFactor());

Upvotes: 1

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