java Lambda访问变量

final int num = 1;

Converter<Integer, String> stringConverter =

        (from) -> String.valueOf(from + num);

stringConverter.convert(2);     // 3

class Lambda4 {

    static int outerStaticNum;

    int outerNum;

    void testScopes() {

        Converter<Integer, String> stringConverter1 = (from) -> {

            outerNum = 23;

            return String.valueOf(from);

        };

        Converter<Integer, String> stringConverter2 = (from) -> {

            outerStaticNum = 72;

            return String.valueOf(from);

        };

    }

}