用于（x：y）执行的Java

Question

I have the following for loop:

for(String s : someString.split("\\s+")){
   //do something
}

Does java execute the split() method each time the loop iterates, or does it do it only once and keep a temp array to iterate on?

Answer 1

It only does it once, and uses that array and interates through it.

Edit: from Mat This is the reference

Answer 2

它在使用之前将数组存储在临时变量中。

Answer 3

在字符串上不执行拆分一次，然后循环遍历结果

Answer 4

The split method is only called once. Think of the structure (also known as a for-each) as follows:

• The second argument is evaluated and kept for the duration of the loop.
• If the argument gives an Iterable or is an array (special case), a check is then made to see if the type of the first argument corresponds with the elements that are returned.
• The process enters the loop and executes the code inside the scope and exits when there are no more elements left.

More information can be had here: http://www.leepoint.net/notes-java/flow/loops/foreach.html

PS: This works with Java 5 minimum.