Using comparable to sort array

Question

I am writing a program where a user adds a set of Integers, and I have to use a comparable to sort the array. Here's how I'm trying to do it:

public class Set<E extends Comparable<E>> {

String s;
String name;
private static final int INITIAL_CAPACITY = 10;
private E[] theData;
private int size = 0;
private int capacity = INITIAL_CAPACITY;

@SuppressWarnings("unchecked")
public Set() {
    theData = (E[]) new Comparable[capacity];
}

public Set(String name) {
    this.name = name;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public void add(E item) {

    if (size == capacity) {
            reallocate();
        }

        if(size == 0){
            theData[0] = item;
            size++;
        }

        for (int i = 0; i < size; i++) {
            int result = item.compareTo(theData[i]);

            if (result < 0){
                theData[i+1] = theData[i];
                theData[i] = item;
                size++;
            }

            if (result > 0){
                theData[i+1] = item;

            }
        }




}

public E get(int index) {
    if (index < 0 || index >= size) {
        throw new ArrayIndexOutOfBoundsException(index);
    }
    return theData[index];
}

public int size() {
    return size;
}

private void reallocate() {
    capacity = 2 * capacity;
    theData = Arrays.copyOf(theData, capacity);
}

}

My idea with the add method is to compare each added item (the number being added to a set). If the item is less than the value of theData[i], shift theData[i] forward a spot into theData[i+1], and place the item in theData[i].

If it is greater than the value in theData[i], place the item in i+1 and leave the lower value in element i.

I've tried re-writing my loops, using a nested loop to iterate through the rest of the elements, but something must be off in my logic because I'm not getting any better results.

Answer 1

each time "size" in add method is initialized to "0", so your for loop is not working, no comparison is done. try using "for(int i=0; i<theData.length; i++)" instead. but after that you may face NullPointerException coz you have initialised initial capacity to 10. writing a separate compare method may work..

public int compare(E o1, E o2) {
       return o1.compareTo(o2);
}