Type inference puzzler

August 31, 2010

Does this compile?

public class Puzzle {
    static Object one() {
        return 1;
    static <T> T safeOne() {
        return (T) one();
    public static void main(String[] args) {
        int one = safeOne();

Take a look at it carefully and think before answering. Why or why not? Once you’ve thought it through, give it a try.

Were you surprised by the result? Now try this: if you tried it out in Eclipse, try it with Sun’s javac. If you tried it with javac, try it with Eclipse.