素的特性。Р源码的具体实现РCollection部分РCollection是List、Set等集合高度抽象出来的接口,它包含了这些集合的基本操作,它主要又分为两大部分:List和Set。РCollection接口Р/**Р * The root interface in the <i>collection hierarchy</i>. A collectionР * represents a group of objects, known as its <i>elements</i>. SomeР * collections allow duplicate elements and others do not. Some are orderedР * and others unordered. The JDK does not provide any <i>direct</i>Р * implementations of this interface: it provides implementations of moreР * specific subinterfaces like <tt>Set</tt> and <tt>List</tt>. This interfaceР * is typically used to pass collections around and manipulate them whereР * maximum generality is desired.Р */Р集合层次结构的根。一个集合包含一组元素对象。有一些集合允许重复元素,有一些不允许;有一些集合元素是有序的有一些不是。Р定义的方法:Рint size()Рboolean isEmpty()Рboolean contains(Object o)РIterator iterator()
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