有没有办法在Java的for-each循环中访问迭代计数器？ [英] Is there a way to access an iteration-counter in Java's for-each loop?

问题描述

在Java的for-each循环中有没有一种方法？

  for（String s：stringArray）{
 doSomethingWith （一个或多个）; 
} 
  

找出循环已经被处理了多久？

除了使用旧的和众所周知的（int i = 0; i< boundary; i ++） - loop，是构造

  int i = 0; 
 for（String s：stringArray）{
 doSomethingWith（s）; 
 i ++; 
 
 
 
 $ b $ p 
 $ b $ p $是唯一可以在for-each循环中使用这种计数器的方法吗？不过，你可以提供自己的计数器。 
 
   原因在于for-each循环内部没有 一个计数器;它基于 Iterable 界面，即它使用一个 Iterator 来循环集合 - 这可能根本不是一个集合，实际上可能根本不是基于索引的东西（比如作为一个链表）。
 
Is there a way in Java's for-each loop
for(String s : stringArray) {
  doSomethingWith(s);
}
to find out how often the loop has already been processed?

Aside from using the old and well-known for(int i=0; i < boundary; i++) - loop, is the construct
int i = 0;
for(String s : stringArray) {
  doSomethingWith(s);
  i++;
}
the only way to have such a counter available in a for-each loop?
解决方案
No, but you can provide your own counter.

The reason for this is that the for-each loop internally does not have a counter; it is based on the Iterable interface, i.e. it uses an Iterator to loop through the "collection" - which may not be a collection at all, and may in fact be something not at all based on indexes (such as a linked list).

                        
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