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中国企业网站建设外包服务市场,自己怎么做软件,成都广告公司工资一般多少,中企动力公司待遇怎么样文章目录 Collection 系列源码分析 (JDK Amazon corretto 11)Collection接口Iterable接口 子接口 QueueQueue的子接口 Deque双端队列 子接口ListArrayList 实现类序列化与反序列化(后续解决)获取Calss对象的方式 主要有三种#xff1a;Arrays工具类System类 LinkedList实现类t… 文章目录 Collection 系列源码分析 (JDK Amazon corretto 11)Collection接口Iterable接口 子接口 QueueQueue的子接口 Deque双端队列 子接口ListArrayList 实现类序列化与反序列化(后续解决)获取Calss对象的方式 主要有三种Arrays工具类System类 LinkedList实现类transient关键字 Vector实现类Stack ListIterator接口 子接口SetHashSet Collection 系列源码分析 (JDK Amazon corretto 11) Collection接口 //public interface IteratorE {} 支持遍历 public interface CollectionE extends IterableE {//主要抽象方法int size();boolean isEmpty();boolean contains(Object o);Object[] toArray();T T[] toArray(T[] a);boolean add(E e);boolean remove(Object o);boolean containsAll(Collection? c);boolean addAll(Collection? extends E c);boolean removeAll(Collection? c);void clear();//… } Iterable接口 IterableE 接口 public interface IterableT {IteratorT iterator();default void forEach(Consumer? super T action) {Objects.requireNonNull(action);for (T t : this) {action.accept(t);}}default SpliteratorT spliterator() {return Spliterators.spliteratorUnknownSize(iterator(), 0);} } IteratorE 接口 public interface IteratorE {boolean hasNext();E next();default void remove() {throw new UnsupportedOperationException(remove);}default void forEachRemaining(Consumer? super E action) {Objects.requireNonNull(action);while (hasNext())action.accept(next());} }//遍历Collection的三种方式 1.传统for循环 2.java forEach写法 3.通过 继承Iterable接口的容器集合方法 iterator()方法返回迭代对象IteratorE,通过hasNext()和next()进行迭代子接口 Queue public interface QueueE extends CollectionE {//就只有这6个抽象方法//增boolean add(E e);boolean offer(E e);//删E remove();E poll();//返回队首元素E element();E peek(); } // poll() peek()队列为空时返回null remove() element() 抛出异常Queue的子接口 Deque双端队列 public interface DequeE extends QueueE {void addFirst(E e);void addLast(E e);boolean offerFirst(E e);boolean offerLast(E e);E removeFirst();E removeLast();E pollFirst();E pollLast();E getFirst();E getLast();E peekFirst();E peekLast();boolean removeFirstOccurrence(Object o);boolean removeLastOccurrence(Object o);void push(E e);E pop();boolean remove(Object o); // 等价boolean removeFirstOccurrence(Object o); }子接口List public interface ListE extends CollectionE {// default jdk8出现 可以在接口中定义默认方法与静态方法default void sort(Comparator? super E c) {Object[] a this.toArray();Arrays.sort(a, (Comparator) c);ListIteratorE i this.listIterator();for (Object e : a) {i.next();i.set((E) e);}}E get(int index);E set(int index, E element);void add(int index, E element);E remove(int index);int indexOf(Object o);int lastIndexOf(Object o);//List Iterators ListIteratorE继承IteratorE 功能更加强大ListIteratorE listIterator(); //完整的List迭代ListIteratorE listIterator(int index);//返回特定位置的迭代器可以向前和向后遍历//返回子ListListE subList(int fromIndex, int toIndex);//迷惑操作 重载了12个of方法 前11个参数个数从0到10,第12个使用了可变长参数 static E ListE of() {return ImmutableCollections.emptyList();}static E ListE of(E e1) {return new ImmutableCollections.List12(e1);}static E ListE of(E e1, E e2) {return new ImmutableCollections.List12(e1, e2);}// 省略SafeVarargsSuppressWarnings(varargs)static E ListE of(E… elements) {switch (elements.length) { // implicit null check of elementscase 0:return ImmutableCollections.emptyList();case 1:return new ImmutableCollections.List12(elements[0]);case 2:return new ImmutableCollections.List12(elements[0], elements[1]);default:return new ImmutableCollections.ListN(elements);}} }ArrayList 实现类 /* 扩容机制 默认情况下新的容量会是原容量的1.5倍。 新容量旧容量右移一位相当于除于2在加上旧容量ArrayList 的底层是用动态数组来实现的。我们初始化一个空的ArrayList 集合还没有添加元素时其实它是个空数组只有当我们添加第一个元素时内部会调用扩容方法并返回最小容量10也就是说ArrayList 初始化容量为10。 当前数组长度小于最小容量的长度时前期容量是10当添加第11个元素时就就扩容便开始可以扩容了ArrayList 扩容的真正计算是在一个grow()里面新数组大小是旧数组的1.5倍如果扩容后的新数组大小还是小于最小容量那新数组的大小就是最小容量的大小后面会调用一个Arrays.copyof方法这个方法是真正实现扩容的步骤。/public class ArrayListE extends AbstractListEimplements ListE, RandomAccess, Cloneable, java.io.Serializable {//6个属性//序列化idprivate static final long serialVersionUID 8683452581122892189L;/** Default initial capacity. 默认容量大小为10/private static final int DEFAULT_CAPACITY 10;/** Shared empty array instance used for empty instances.在传入初始容量的构造函数中如果给的初始化容量为0使用这个数组/private static final Object[] EMPTY_ELEMENTDATA {};/** Shared empty array instance used for default sized empty instances. We* distinguish this from EMPTY_ELEMENTDATA to know how much to inflate when* first element is added./private static final Object[] DEFAULTCAPACITY_EMPTY_ELEMENTDATA {};/** The array buffer into which the elements of the ArrayList are stored.* The capacity of the ArrayList is the length of this array buffer. Any* empty ArrayList with elementData DEFAULTCAPACITY_EMPTY_ELEMENTDATA* will be expanded to DEFAULT_CAPACITY when the first element is added.具体的存储通过数组进行/transient Object[] elementData; // non-private to simplify nested class access/** The size of the ArrayList (the number of elements it contains).* 元素的数量 通过属性来确定* serial/private int size;//构造方法//1.空的构造public ArrayList() {this.elementData DEFAULTCAPACITY_EMPTY_ELEMENTDATA;}//2.给定容量public ArrayList(int initialCapacity) {if (initialCapacity 0) {this.elementData new Object[initialCapacity];} else if (initialCapacity 0) {// 用到了6个属性之一this.elementData EMPTY_ELEMENTDATA;} else {throw new IllegalArgumentException(Illegal Capacity: initialCapacity);}}//3.通过其他集合创建ArrayListpublic ArrayList(Collection? extends E c) { // Collection? extends E ?为泛型中的通配符Object[] a c.toArray();if ((size a.length) ! 0) {//类名.class获取这个类的Class对象。只是三种方式之一if (c.getClass() ArrayList.class) {elementData a;} else {elementData Arrays.copyOf(a, size, Object[].class);}} else {// replace with empty array.elementData EMPTY_ELEMENTDATA;}}// Integer.MAX_VALUE0x7fffffff 4字节 1位符号位为0然后全是1private static final int MAX_ARRAY_SIZE Integer.MAX_VALUE - 8;//将容量缩减到数组元素数目大小public void trimToSize() {modCount;if (size elementData.length) {elementData (size 0)? EMPTY_ELEMENTDATA: Arrays.copyOf(elementData, size);}}//扩容用的方法private Object[] grow(int minCapacity) {return elementData Arrays.copyOf(elementData,newCapacity(minCapacity));}private Object[] grow() {return grow(size 1);}private int newCapacity(int minCapacity) {// overflow-conscious codeint oldCapacity elementData.length;int newCapacity oldCapacity (oldCapacity 1);if (newCapacity - minCapacity 0) {if (elementData DEFAULTCAPACITY_EMPTY_ELEMENTDATA)return Math.max(DEFAULT_CAPACITY, minCapacity);if (minCapacity 0) // overflowthrow new OutOfMemoryError();return minCapacity;}return (newCapacity - MAX_ARRAY_SIZE 0)? newCapacity: hugeCapacity(minCapacity);}private void add(E e, Object[] elementData, int s) {if (s elementData.length)elementData grow();elementData[s] e;size s 1;}public boolean add(E e) {modCount;add(e, elementData, size);return true;}//…其他后续再看吧 }ArrayList实现了Serializable接口: 序列化与反序列化(后续解决) 获取Calss对象的方式 主要有三种 通过Class.forName(“类的全名称”)获取通过已经实例化的对象获取getClass()方法获取通过类名.class获取 Arrays工具类 public class Arrays {// 为左移 1左移13位private static final int MIN_ARRAY_SORT_GRAN 1 13;//copyOf 最终还是调用System.arraycopy见下文public static T T[] copyOf(T[] original, int newLength) {return (T[]) copyOf(original, newLength, original.getClass());} }System类 public final class System {HotSpotIntrinsicCandidatepublic static native void arraycopy(Object src, int srcPos,Object dest, int destPos,int length); }LinkedList实现类 //实现ListE 和 DequeE 所以LinkedList是双向链表 public class LinkedListEextends AbstractSequentialListEimplements ListE, DequeE, Cloneable, java.io.Serializable {transient int size 0;/** Pointer to first node./transient NodeE first;/** Pointer to last node./transient NodeE last;//NodeE 是一个内部类双向链表结构主要由Node来维护private static class NodeE {E item;NodeE next;NodeE prev;Node(NodeE prev, E element, NodeE next) {this.item element;this.next next;this.prev prev;}}/** Links e as first element.将新元素链接到表头/private void linkFirst(E e) {final NodeE f first;final NodeE newNode new Node(null, e, f);first newNode;if (f null)last newNode;elsef.prev newNode;size;modCount;}/** Links e as last element.将新元素链接到表尾/void linkLast(E e) {final NodeE l last;final NodeE newNode new Node(l, e, null);last newNode;if (l null)first newNode;elsel.next newNode;size;modCount;}/** Inserts element e before non-null Node succ.链接到某个非空节点前面/void linkBefore(E e, NodeE succ) {// assert succ ! null;final NodeE pred succ.prev;final NodeE newNode new Node(pred, e, succ);succ.prev newNode;if (pred null)first newNode;elsepred.next newNode;size;modCount;}/** Unlinks non-null first node f./private E unlinkFirst(NodeE f) {// assert f first f ! null;final E element f.item;final NodeE next f.next;f.item null;f.next null; // help GCfirst next;if (next null)last null;elsenext.prev null;size–;modCount;return element;}/** Unlinks non-null last node l./private E unlinkLast(NodeE l) {// assert l last l ! null;final E element l.item;final NodeE prev l.prev;l.item null;l.prev null; // help GClast prev;if (prev null)first null;elseprev.next null;size–;modCount;return element;}/** Unlinks non-null node x.*/E unlink(NodeE x) {// assert x ! null;final E element x.item;final NodeE next x.next;final NodeE prev x.prev;if (prev null) {first next;} else {prev.next next;x.prev null;}if (next null) {last prev;} else {next.prev prev;x.next null;}x.item null;size–;modCount;return element;}/后面这6个方法都是对上面方法的封装/public E getFirst() {final NodeE f first;if (f null)throw new NoSuchElementException();return f.item;}public E getLast() {final NodeE l last;if (l null)throw new NoSuchElementException();return l.item;}public E removeFirst() {final NodeE f first;if (f null)throw new NoSuchElementException();return unlinkFirst(f);}public E removeLast() {final NodeE l last;if (l null)throw new NoSuchElementException();return unlinkLast(l);}public void addFirst(E e) {linkFirst(e);}public void addLast(E e) {linkLast(e);} }transient关键字 Java语言的关键字变量修饰符如果用transient声明一个实例变量当对象存储时它的值不需要维持。换句话来说就是用transient关键字标记的成员变量不参与序列化过程 Vector实现类 //底层和ArrayList差不多都是基于数组实现 public class VectorEextends AbstractListEimplements ListE, RandomAccess, Cloneable, java.io.Serializable {protected Object[] elementData;protected int elementCount;protected int capacityIncrement;/** use serialVersionUID from JDK 1.0.2 for interoperability /private static final long serialVersionUID -2767605614048989439L;//4个构造方法public Vector(int initialCapacity, int capacityIncrement) {super();if (initialCapacity 0)throw new IllegalArgumentException(Illegal Capacity: initialCapacity);this.elementData new Object[initialCapacity];this.capacityIncrement capacityIncrement;}public Vector(int initialCapacity) {this(initialCapacity, 0);}public Vector() {this(10);}public Vector(Collection? extends E c) {Object[] a c.toArray();elementCount a.length;if (c.getClass() ArrayList.class) {elementData a;} else {elementData Arrays.copyOf(a, elementCount, Object[].class);}}private static final int MAX_ARRAY_SIZE Integer.MAX_VALUE - 8;public int indexOf(Object o) {return indexOf(o, 0);}public synchronized int indexOf(Object o, int index) {if (o null) {for (int i index ; i elementCount ; i)if (elementData[i]null)return i;} else {for (int i index ; i elementCount ; i)if (o.equals(elementData[i]))return i;}return -1;}public synchronized int lastIndexOf(Object o) {return lastIndexOf(o, elementCount-1);}public synchronized int lastIndexOf(Object o, int index) {if (index elementCount)throw new IndexOutOfBoundsException(index elementCount);if (o null) {for (int i index; i 0; i–)if (elementData[i]null)return i;} else {for (int i index; i 0; i–)if (o.equals(elementData[i]))return i;}return -1;}public synchronized E elementAt(int index) {if (index elementCount) {throw new ArrayIndexOutOfBoundsException(index elementCount);}return elementData(index);}public synchronized E firstElement() {if (elementCount 0) {throw new NoSuchElementException();}return elementData(0);}public synchronized E lastElement() {if (elementCount 0) {throw new NoSuchElementException();}return elementData(elementCount - 1);}public synchronized void setElementAt(E obj, int index) {if (index elementCount) {throw new ArrayIndexOutOfBoundsException(index elementCount);}elementData[index] obj;}public synchronized void removeElementAt(int index) {if (index elementCount) {throw new ArrayIndexOutOfBoundsException(index elementCount);}else if (index 0) {throw new ArrayIndexOutOfBoundsException(index);}int j elementCount - index - 1;if (j 0) {System.arraycopy(elementData, index 1, elementData, index, j);}modCount;elementCount–;elementData[elementCount] null; / to let gc do its work */}public synchronized void insertElementAt(E obj, int index) {if (index elementCount) {throw new ArrayIndexOutOfBoundsException(index elementCount);}modCount;final int s elementCount;Object[] elementData this.elementData;if (s elementData.length)elementData grow();System.arraycopy(elementData, index,elementData, index 1,s - index);elementData[index] obj;elementCount s 1;}public synchronized void addElement(E obj) {modCount;add(obj, elementData, elementCount);}public synchronized boolean removeElement(Object obj) {modCount;int i indexOf(obj);if (i 0) {removeElementAt(i);return true;}return false;}public synchronized void removeAllElements() {final Object[] es elementData;for (int to elementCount, i elementCount 0; i to; i)es[i] null;modCount;}public synchronized E set(int index, E element) {}public synchronized boolean add(E e) {}public boolean remove(Object o) {return removeElement(o);}public void add(int index, E element) {insertElementAt(element, index);}public synchronized E remove(int index) {}public void clear() {removeAllElements();} }Stack public class StackE extends VectorE {public Stack() {}public E push(E item) {addElement(item);return item;}public synchronized E pop() {E obj;int len size();obj peek();removeElementAt(len - 1);return obj;}public synchronized E peek() {int len size();if (len 0)throw new EmptyStackException();return elementAt(len - 1);}public boolean empty() {return size() 0;}public synchronized int search(Object o) {int i lastIndexOf(o);if (i 0) {return size() - i;}return -1;} }ListIterator接口 // ListIteratorE 功能更加强大 // 对于有n的元素的列表 共有n1个游标位置public interface ListIteratorE extends IteratorE {boolean hasNext();//判断游标后有没有元素E next();//返回游标后的元素并后移boolean hasPrevious();//判断游标前有没有元素E previous();//返回游标前的元素并前移int nextIndex();//返回游标后边元素的索引位置int previousIndex();//返回游标前面元素的位置初始时为 -1/删除迭代器最后一次操作的元素注意事项和 set 一样。/void remove();/更新迭代器最后一次操作的元素为 E也就是更新最后一次调用 next() 或者 previous() 返回的元素。 注意当没有迭代也就是没有调用 next() 或者 previous() 直接调用 set 时会报 java.lang.IllegalStateException 错;/void set(E e);void add(E e);//在游标 前面 插入一个元素。注意是前面 }子接口Set public interface SetE extends CollectionE {//没看出有什么新的东西 }HashSet //底层使用HashMap实现 public class HashSetEextends AbstractSetEimplements SetE, Cloneable, java.io.Serializable {static final long serialVersionUID -5024744406713321676L;//HashMap实现private transient HashMapE,Object map;// Dummy value to associate with an Object in the backing Mapprivate static final Object PRESENT new Object(); }