Commit 016ec72

committed

Merge pull request giantray#46 from ArronDon/master

Create how-does-the-java-for-each-loop-work.md

2 parents f092ace + 5d872de commit 016ec72Copy full SHA for 016ec72

File tree

+23

-0

lines changed

+23

-0

lines changed

Lines changed: 23 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,23 @@`
	`1`	`+## Java的foreach循环是如何工作的?`
	`2`	`+### 问题`
	`3`	+````java
	`4`	`+List<String> someList = new ArrayList<String>();`
	`5`	`+// add "monkey", "donkey", "skeleton key" to someList`
	`6`	`+for (String item : someList) {`
	`7`	`+ System.out.println(item);`
	`8`	`+}`
	`9`	+````
	`10`	`+如果不用for each语法,等价的循环语句是什么样的?`
	`11`	`+### 回答`
	`12`	+````java
	`13`	`+for(Iterator<String> i = someList.iterator(); i.hasNext(); ) {`
	`14`	`+ String item = i.next();`
	`15`	`+ System.out.println(item);`
	`16`	`+}`
	`17`	+````
	`18`	`+记住,如果需要在循环中使用i.remove;或者以某种方式获取实际的iterator,你不能使用for(:)语法,因为实际的Iterator很难被推断出来。`
	`19`	`+正如Denis Bueno写的那样,这种代码对任何实现了Iterable接口的对象都奏效。`
	`20`	`+此外,如果for(:)句法中右侧是一个数组而不是一个可迭代对象,那么内部代码用一个int型的计数器来防止数组越界。详见Java Language Specification:`
	`21`	`+http://docs.oracle.com/javase/specs/jls/se8/html/jls-14.html#jls-14.14.2`
	`22`	`+`
	`23`	`+stackoverflow链接:http://stackoverflow.com/questions/85190/how-does-the-java-for-each-loop-work`

Comments

(0)