自己手寫簡單的ArrayList

public class MyArrayList {

	Object[] elements; //用於存儲元素
	int size=0;  //用於指示當前存的元素個數
	
	public MyArrayList(){
		elements=new Object[5];
	}
	
	public void add(Object o){
		ensureCapacity();
		elements[size++]=o;
	}
	
	public void ensureCapacity(){
		if(size==elements.length){
			int newLength=size*2;
			Object[] temp=new Object[newLength];
			for(int i=0;i<size;i++) temp[i]=elements[i];
			elements=temp;
		}
	}
	
	public boolean remove(Object o){
		for(int i=0;i<size;i++){
			if(o.equals(elements[i])){
				for(int j=i;j<size-1;j++){
					elements[j]=elements[j+1];
				}
				elements[--size]=null;
				return true;
			}
		}
		return false;		
	}
	
	public int size(){
		return size;
	}
	
    public String toString() {
    	StringBuffer sb=new StringBuffer("[");
    	if(size>0){
    		for(int i=0;i<size;i++){
    			if(i!=size-1){
    				sb.append(elements[i]+", ");
    			}else{
    				sb.append(elements[i]+"]");
    			}
    			
    		}
    	}
    	if(size==0) sb.append("]");
    	return sb.toString();
    }
}