How to access variables using java Lambda

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);
        };
    }
}