Iterable&Iterator&Collection

Iterable

概述

Implementing this interface allows an object to be the target of the "for-each loop" statement.

实现Iterable接口 允许一个对象 作为 foreach遍历的目标；

 

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public interface Iterable<T> {       Iterator<T> iterator();   }

　　

Iterator

概述

An iterator over a collection.
{@code Iterator} takes the place of {@link Enumeration} in the Java Collections Framework.

Collection的iterator；

Iterator替代了Java集合框架的Enumeration；

 

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public interface Iterator<E> {       boolean hasNext();     E next();     default void remove() {         throw new UnsupportedOperationException("remove");     }   }

　　

Collection

概述

The root interface in the <i>collection hierarchy</i>.
A collection represents a group of objects, known as its <i>elements</i>.
Some collections allow duplicate elements and others do not.
Some are ordered and others unordered.
The JDK does not provide any <i>direct</i> implementations of this interface: it provides implementations of more specific subinterfaces like <tt>Set</tt> and <tt>List</tt>.
This interface is typically used to pass collections around and manipulate them where maximum generality is desired.

集合的root接口；

collection代表一组对象，称对象为元素；

jdk没有提供直接的collection的实现，提供了子接口：Set、List；

 

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public interface Collection<E> extends Iterable<E> {   }