JDK源码阅读(三) Collection接口,Iterable接口

package java.util;



public interface Collection<E> extends Iterable<E> {
 
    //返回该集合中元素的数量 
    int size();
    //判断该集合中元素是否为空 size() == 0
    boolean isEmpty();
    
    boolean contains(Object o);
    
    Iterator<E> iterator();

    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);
   
    boolean retainAll(Collection<?> c);

    void clear();
   
    boolean equals(Object o);

    int hashCode();
}

package java.lang;

import java.util.Iterator;

/** Implementing this interface allows an object to be the target of
 *  the "foreach" statement.
 * @since 1.5
 */
public interface Iterable<T> {

    /**
     * Returns an iterator over a set of elements of type T.
     * 
     * @return an Iterator.
     */
    Iterator<T> iterator();
}