标签:Node capacityIncrement int elementData newCapacity Collection minCapacity 源码
ArrayList源码
/** *添加元素, */ public boolean add(E e) { ensureCapacityInternal(size + 1); // 扩容 elementData[size++] = e; return true; } /** *ArrayList初始为空数组{},minCapacity第一次为1==》默认长度10 */ private void ensureCapacityInternal(int minCapacity) { if (elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA) { minCapacity = Math.max(DEFAULT_CAPACITY, minCapacity); } ensureExplicitCapacity(minCapacity); } /** * 当minCapacity小于数组长度时==》扩容grow */ private void ensureExplicitCapacity(int minCapacity) { modCount++; // overflow-conscious code if (minCapacity - elementData.length > 0) grow(minCapacity); } /** * 新的数组扩容为1.5倍, */ private void grow(int minCapacity) { int oldCapacity = elementData.length; int newCapacity = oldCapacity + (oldCapacity >> 1); //1.5倍原数组长度扩容 if (newCapacity - minCapacity < 0)//长度还有剩余就继续使用 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); // }
Vector源码:
/** * Vector的无参构造会默认指定10大小, */ public Vector() { this(10); } /** * 第一次容量增长系数:capacityIncrement为0 */ public Vector(int initialCapacity) { this(initialCapacity, 0); } public Vector(int initialCapacity, int capacityIncrement) { super(); if (initialCapacity < 0) throw new IllegalArgumentException("Illegal Capacity: "+ initialCapacity); this.elementData = new Object[initialCapacity]; this.capacityIncrement = capacityIncrement; } ====== /** * 添加 synchronized 修饰==》线程安全 */ public synchronized boolean add(E e) { modCount++; ensureCapacityHelper(elementCount + 1); elementData[elementCount++] = e; return true; } /** * 当最小容量小于数组长度时==》扩容 */ private void ensureCapacityHelper(int minCapacity) { // overflow-conscious code if (minCapacity - elementData.length > 0) grow(minCapacity); } /** * capacityIncrement 第一次为0,后面为10,==》每次扩容2倍 */ private void grow(int minCapacity) { // overflow-conscious code int oldCapacity = elementData.length; int newCapacity = oldCapacity + ((capacityIncrement > 0) ? capacityIncrement : oldCapacity); if (newCapacity - minCapacity < 0) newCapacity = minCapacity; if (newCapacity - MAX_ARRAY_SIZE > 0) newCapacity = hugeCapacity(minCapacity); elementData = Arrays.copyOf(elementData, newCapacity); }
LinkedList源码:
/** * LinkedList新增,双向链表 */ private static class Node<E> { E item; Node<E> next; Node<E> prev; Node(Node<E> prev, E element, Node<E> next) { this.item = element; this.next = next; this.prev = prev; } } public boolean add(E e) { linkLast(e); return true; } /** * Linked首次first 、last 为同一节点,后续默认插入到最后节点 */ void linkLast(E e) { final Node<E> l = last; final Node<E> newNode = new Node<>(l, e, null); last = newNode; if (l == null) first = newNode; else l.next = newNode; size++; modCount++; }
HashSet源码:
标签:Node,capacityIncrement,int,elementData,newCapacity,Collection,minCapacity,源码 来源: https://www.cnblogs.com/Jiedeman/p/16365116.html
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