Person[] p = new Person[10];//Person是自定義的一個(gè)類型
ArrayList<Person> pList = new ArrayList<Person>();
上邊的p跟pList都能用來存放person類型的數(shù)據(jù),怎么選擇?ArrayList可以實(shí)現(xiàn)的功能數(shù)組也能實(shí)現(xiàn),為啥會(huì)有ArrayList呢?
1 回答
慕桂英546537
TA貢獻(xiàn)1848條經(jīng)驗(yàn) 獲得超10個(gè)贊
ArrayList底層就是Object數(shù)組
transient Object[] elementData
不過它可以動(dòng)態(tài)擴(kuò)容，這是它的擴(kuò)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);
}添加回答
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