It’s called a for-each or enhanced for
statement. See the JLS §14.14.2.
It’s syntactic sugar provided by the compiler for iterating over Iterable
s and arrays. The following are equivalent ways to iterate over a list:
List<Foo> foos = ...;
for (Foo foo : foos)
{
foo.bar();
}
// equivalent to:
List<Foo> foos = ...;
for (Iterator<Foo> iter = foos.iterator(); iter.hasNext();)
{
Foo foo = iter.next();
foo.bar();
}
and these are two equivalent ways to iterate over an array:
int[] nums = ...;
for (int num : nums)
{
System.out.println(num);
}
// equivalent to:
int[] nums = ...;
for (int i=0; i<nums.length; i++)
{
int num = nums[i];
System.out.println(num);
}