Java8のラムダとクロージャ

http://d.hatena.ne.jp/nowokay/comment?date=20130522#c

import java.util.List;
import java.util.function.Supplier;
import java.util.ArrayList;

public class MyClass {
    public static void main(String args[]) {
        List<Supplier<String>> list = new ArrayList<>();
        for(int i = 1; i <= 10; ++i){
            list.add( () -> String.format("%d番目", i));
        }
        list.forEach(s -> System.out.println(s.get()));
    }
}

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/MyClass.java:9: error: local variables referenced from a lambda expression must be final or effectively final
            list.add( () -> String.format("%d番目", i));
                                                  ^
1 error