Partially filled array - get minimum value and toString

Question

I am working on a bonus for one of my assignments. I'm supposed to create a really large array, but the user doesn't have to use all the slots in the array. Previously I used an enhanced for loop for a regular array that had all its indexes filled. I'm not really sure how to change that to fit the new criteria.

Whenever I enter the numbers in the tester, the toString returns the empty spots and the minimum value returns 0 because the empty spot's values are 0s.

public class NumberSetBonus
{   
    private int[] numbers;
    private int count;

    /**
     * Constructs an empty NumberSet of a specified size
     * @param size the number of elements in the set
     */
    public NumberSetBonus(int size)
    {
        numbers = new int[size];
        count = 0;
    }

    /**
     * addNumber adds a number to the number set 
     * @param num new number
     */
    public void addNumber(int num)
    {
        numbers[count] = num;
        count++; 
    }

    /**
     * getMin finds the minimum value stored in the NumberSet
     * @return the minimum value
     * precondition:  array is full of values
     */
    public int getMin()
    {
        int min = numbers[0];

        for(int n : numbers)
            if(n < min)
                min = n;

        return min;
    }

    /**
     * getMax finds the maximum value stored in the NumberSet
     * @return the maximum value
     * precondition:  array is full of values
     */
    public int getMax()
    {
        int max = numbers[0];

        for(int n : numbers)
            if(n > max)
                max = n;

        return max;
    }

    /** 
     * find determines whether a specified value exists in the set.
     * @param num the number to find
     * @return whether the value exists
     */
    public boolean find(int num)
    {
        boolean find = true;

        for(int n : numbers)
            if(n == num)
                find = true;    

        return find;    
    }

    /**
     * getSum calculates the sum of the values in the set.
     * @return the sum
     */
    public int getSum()
    {
        int sum = 0;

        for(int n : numbers)
            sum += n;

        return sum;
    }

    /**
     * getMean calculates the mean of the values in the set.
     * @return the mean as a double
     * precondition:  array is full of values
     * NOTE: use the length field of the array
     */ 
    public double getMean()
    {
        return getSum() / (double) numbers.length;
    }

    /**
     * count counts the occurrence of a specified number within the set.
     * @param num the number to find
     * @return the number of times num occurs in the set
     */
    public int count(int num)
    {
        int quantity = 0;

        for(int n : numbers)
            if(n == num)
                quantity++;

        return quantity;
    }

    /**
     * toString returns a String containing the values in the set on a 
     * single line with a space between each value.
     * @return the String version of the set
     */
    public String toString()
    {
        String set = " ";

        for(int n : numbers)
            set += n + " "; 
        return set;
    }
}

Here's my tester, where I ask for the user's input, and where the toString() returns the 0s

public class NumberSetBonusTester
{
    public static void main(String[] args)
    {
        Scanner input = new Scanner(System.in);
        final int LENGTH = 100;
        NumberSetBonus list = new NumberSetBonus(LENGTH);
        int arraySize = 0;

        System.out.print("You can enter up to 100 numbers in this array. \nType in a negative number if you want to stop adding numbers.\nEnter a number: ");

        while(arraySize < LENGTH)
        {
            int number = input.nextInt();
            if(number <= 0)
                break;
            list.addNumber(number);
            arraySize++;
        }           

        System.out.print("\nset 1:\t\t");
        System.out.println(list);
        System.out.println("list sum:\t" + list.getSum());
        System.out.println("list mean:\t" + list.getSum() / arraySize);
        System.out.println("list max:\t" + list.getMax());
        System.out.println("list min:\t" + list.getMin());
        System.out.println();
        System.out.print("Enter a number to find ==> ");
        int searchNum = input.nextInt();
        if (list.find(searchNum))
            System.out.println(searchNum + " is in the set " + list.count(searchNum) + " times");
        else
            System.out.println(searchNum + " is not in the set");
    }
}

Answer 1

You can simply change all your for loops to the form for (int i = 0; i < count; i++) - this way the loops will only loop the numbers that were actually set, not all numbers in the array.

BTW: If you ever need some variable-sized array in the future you can use a List (from the java.util package). In your example I would use an ArrayList<Integer>. This is a list that uses an array internally, but increases its size if the array gets too small (by creating a new array and copying the contents).