public ArrayList(Collection<? extends E> c) {
elementData = c.toArray();
if ((size = elementData.length) != 0) {
// c.toArray might (incorrectly) not return Object[] (see 6260652)
if (elementData.getClass() != Object[].class)
elementData = Arrays.copyOf(elementData, size, Object[].class);
} else {
// replace with empty array.
this.elementData = EMPTY_ELEMENTDATA;
}
}
我们看到toArray,会有疑惑,如果返回的不是拷贝,那原数组改变时也会影响到elementData,所以我们找到set(set也是toArray)的toArray的声明,并查看注释
set的toArray声明
this method must allocate a new array even if this set is backed by an array.
所以说,toArray必须返回拷贝的数组,不能直接返回引用本身。
elementData
get
elementData
https://www.cnblogs.com/liuling/archive/2013/05/05/transient.html
transient声明的成员不可被序列化, 反序列化后,该成员也只能被初始化。
未检查的cast
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);
}
int newCapacity = oldCapacity + (oldCapacity >> 1);
放大为1.5倍