都可以对容器进行从头到尾的遍历 for(String s:list){ System.out.PRint(s); } Iterator it = list.iterator(); while(it.hasNext()){ System.out.print(it.next()); }实现了Iterable接口的类，for-each在编译器中的实现就是IteratorList<String> list = new ArrayList<String>();for(String s:list){ System.out.print(s);}
不同点
For-each只能读取元素内容，无法对collection进行结构性修改（ps:结构性修改一般指改变大小，或者在迭代过程中打乱）public class test { static class Person { private int id; private String name; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } @Override public String toString() { return "Person [id=" + id + ", name=" + name + "]"; } } public static void main(String[] args) { List<Person> list = new ArrayList<Person>(); Person p1 = new Person(); for (int i = 0; i < 5; i++) { Person p = new Person(); p.setId(1); p.setName("name"); list.add(p); } for (Person p : list) { System.out.println(p); list.remove(p);//throws ConcurrentModificationException list.add(p1);//throws ConcurrentModificationException } }}For-each只能读取当前元素，前后元素不可见，而部分Iterator可以获取前后元素（如实现了ListIterator接口的..etc）For-each只能单向从头到尾遍历，Iterator可以实现双向遍历For-each是语法糖，有很好的阅读体验，同时避免了迭代器变量多次出现减小BUG几率；Iterator模式是设计模式之一：迭代器模式
