Funny error with Java’s extended for-loop
Java 5 introduced the enhanced for-loop – or for-each loop – which simplifies iterating over many types of collections. Have a look at this simple piece of code and tell me what’s wrong:package de.danielschneller.blog.iterator;
import java.util.HashSet;
import java.util.Set;
public class Demo {
public static void main(String[] args) {
Set set = new HashSet();
set.add("Value 1");
set.add("Value 2");
set.add("Value 3");
set.add("Value 4");
set.add("Value 5");
synchronized (set) {
for (String tEntry : set) {
if (tEntry.endsWith("3")) {
System.out.println("3 has to go");
set.remove(tEntry);
} else {
System.out.println(tEntry + " may stay");
}
}
}
}
}When I wrote this I naively expected something like this to be written out(the order of the iteration is undefined for a HashSet, but bear with me:Value 5 may stay
Value 2 may stay
3 has to go
Value 4…
Value 2 may stay
3 has to go
Value 4…