ArrayList中的size问题

以下是我自己写ArrayList的代码，没有给其中的变量size赋值，但是结果输出的size确实对的，我觉得应该添加我在下面注释的代码才应该对呀


public class SxAarryList  {
    private Object[] elementData;
    private int size;
    public int size(){
        return size;
    }
   
    public boolean isEmpty(){
    return size==0;
    }
    public SxAarryList(){
        this(10);
        
    }
   
    public SxAarryList(int initicalCapacity){
        if(initicalCapacity<0){
            try {
                throw new Exception();
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
       //size=initicalCapacity 是这个地方应该加这句代码呀，为什么不加也是对的
        elementData=new Object[initicalCapacity];
    }
   
    public void add(Object obj)
    {
        if(size==elementData.length){
            Object[] newArray=new Object[size* 2+1];
            System.arraycopy(elementData, 0, newArray, 0, elementData.length);
            //for(int i=0;i<elementData.length;i++){
                //newArray[i]=elementData[i];
            //}
            elementData=newArray;
        }
        
        
        elementData[size]=obj;
        size++;
    }
   
    public Object get(int index){
        if(index<0||index>=size){
            try {
                throw new Exception();
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        return elementData[index];
    }
    public void remove(int index){
        
    }
   
     public static void main(String[] args) {
        SxAarryList list =new SxAarryList(3);
        list.add("666");
        list.add("bbb");
        list.add("fff");
        list.add("fff");
        list.add("fff");
        list.add("fff");
        list.add("fff");
        System.out.println(list.size());
        System.out.println(list.get(3));

        
        
    }

}