JAVA进阶训练营(2021最新版)
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接着看实质上调用的扩容办法grow，每次扩容都是之前容量的1.5倍
// 扩容，初次为10、后面为之前的1.5倍 private void grow(int minCapacity) { // overflow-conscious code int oldCapacity = elementData.length; // 初始时elementData为空数组，这里为0 int newCapacity = oldCapacity + (oldCapacity >> 1); // 扩容为1.5倍 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); } 复制代码
3.3 remove(int index)
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删除指定位置index，实质上是System.arraycopy复制，相当于移位
public E remove(int index) { rangeCheck(index); modCount++; E oldValue = elementData(index); int numMoved = size - index - 1; if (numMoved > 0) System.arraycopy(elementData, index+1, elementData, index, numMoved); elementData[--size] = null; // clear to let GC do its work return oldValue; } 复制代码
3.4 remove(E element)
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删除指定元素（当有多个，只会移除最前面的一个）
// 遍历，找出相等的第一个元素运用fastRemove移除 public boolean remove(Object o) { if (o == null) { for (int index = 0; index < size; index++) if (elementData[index] == null) { fastRemove(index); return true; } } else { for (int index = 0; index < size; index++) if (o.equals(elementData[index])) { fastRemove(index); return true; } } return false; } // 跟remove(index)大致相同，只是少了rangeCheck和返回值（毕竟不需求） private void fastRemove(int index) { modCount++; int numMoved = size - index - 1; if (numMoved > 0) System.arraycopy(elementData, index+1, elementData, index, numMoved); elementData[--size] = null; // clear to let GC do its work } 复制代码
