数组跟list的使用

Question

Person[] p = new Person[10];//Person是自定义的一个类型
ArrayList<Person> pList = new ArrayList<Person>();

上边的p跟pList都能用来存放person类型的数据,怎么选择?
ArrayList可以实现的功能数组也能实现,为啥会有ArrayList呢?

Answer 1

ArrayList底层就是Object数组 transient Object[] elementData 不过它可以动态扩容，这是它的扩容方法 private void grow(int minCapacity) { // overflow-conscious code int oldCapacity = elementData.length; int newCapacity = oldCapacity + (oldCapacity >> 1); if (newCapacity - minCapacity < 0) newCapacity = minCapacity; if (newCapacity - MAX_ARRAY_SIZE > 0) newCapacity = hugeCapacity(minCapacity); // minCapacity is usually close to size, so this is a win: elementData = Arrays.copyOf(elementData, newCapacity); }