Look at how the for-each loop internally works, see How does the Java ‘for each’ loop work?
for(Iterator<String> i = someList.iterator(); i.hasNext(); ) {
String item = i.next();
System.out.println(item);
}
Each time it declares the String variable item. Hence in your case its doing essentially
State state;
\\and inside
State state = i.next();
which obviously wont work. Now inside the implementation, they it could rather only do
item = i.next();
but then you always have to define that item outside for-each, which would be pain majority of time.