// Demonstrate a method reference for a static method.
// A functional interface for string operations.
interface StringFunc {
    String func(String n);
}
// This class defines a static method called strReverse().
class MyStringOps {
    // A static method that reverses a string.
    static String strReverse(String str) {
        String result = "";
        int i;
        for(i = str.length()-1; i >= 0; i--) {
            result += str.charAt(i);
        }
        return result;
    }
}
class MethodRefDemo {
    // This method has a functional interface as the type of
    // its first parameter. Thus, it can be passed any instance
    // of that interface, including a method reference.
    static String stringOp(StringFunc sf, String s) {
        return sf.func(s);
    }
    public static void main(String args[])
    {
        String inStr = "Lambdas add power to Java";
        String outStr;
        // Here, a method reference to strReverse is passed to stringOp().
        outStr = stringOp(MyStringOps::strReverse, inStr);
        System.out.println("Original string: " + inStr);
        System.out.println("String reversed: " + outStr);
    }
}