java - For-Each能够遍历数组(Array)的原理是什么？

Question

比如这样一个例子...

Egg[] eggs = {new Egg(), new Egg()};
for (Egg egg : eggs) {
    egg.eat();
}

自己尝试了一下，冒号后面的对象只要不是数组或者Iterable对象，都是会报出编译错误。
Can only iterate over an array or an instance of java.lang.Iterable

然后我通过调试发现For-Each实际上是不断地调用迭代器的hasNext()和next()方法来实现对Collection类遍历的。

那么遍历数组的原理是什么呢？也是在JDK层面实现的吗？

Answer 1

Yes, this is just syntax sugar~ If you can foreach, you must implement the Iterable interface~

Answer 2

The principle that For-Each can traverse an array is that the JVM translates it into a traditional For-Index loop during compilation, that is:

for (int i = 0; i < arr.length; i++) {
...
}

This is also a syntax sugar provided by the JVM for Java.