A basic ArrayList implementation(Java)

MyArrayList.java

public class MyArrayList {

    private static final int DEFAULT_CAPACITY = 10;

    private int theSize;
    private int[] theItems;

    public MyArrayList() {
        clear();
    }

    public void clear() {
        theSize = 0;
        ensureCapacity(DEFAULT_CAPACITY);
    }

    public void ensureCapacity(int newCapacity) {
        if (newCapacity < theSize) return;

        int[] old = theItems;
        theItems = (int[]) new Object[newCapacity];
        for (int i = 0; i < size(); i++) {
            theItems[i] = old[i];
        }
    }

    public int size() {
        return theSize;
    }

    public boolean isEmpty() {
        return size() == 0;
    }

    public void trimToSize() {
        ensureCapacity(size());
    }

    public int get(int index) {
        if (index < 0 || index >= size()) throw new ArrayIndexOutOfBoundsException();

        return theItems[index];
    }

    public int set(int index, int newVal) {
        if (index < 0 || index >= size()) throw new ArrayIndexOutOfBoundsException();
        int old = theItems[index];
        theItems[index] = newVal;
        return old;
    }

    /**
     * add the element to the end of list
     *
     * @param element is the element you want to add
     * @return true if add successfully, otherwise return false
     */
    public boolean add(int element) {
        add(size(), element);
        return true;
    }

    // remove from specific spot
    public int remove(int index) {
        int removeItem = theItems[index];
        // Shift everything to the left
        for (int i = index; i < size() - 1; i++) {
            theItems[i] = theItems[i + 1];
        }
        theSize--;
        return removeItem;
    }
}