Is it possible to use a specific method of an object (or a static method) as a functor in Java 8

Question

I am trying to understand functional interfaces in Java 8. Suppose f() to the functor:

public class A {
    private double a;

    public A(double a_) {
        a = a_;
    }

    public void f(double[] b, double[] c, double[] d) {
        d[0] = a * (b[0] + c[0]);
    }
}

Is it possible to create a similar construction using the Java 8 functional interface ?

public class B {
    public double g(Function funct, double[] b, double[] c, double[] d) {
        funct(b, c, d); //Call the functor, minor calculations
        return d[0];
    }

    public static void main(String[] args) {
        A a = new A(1);
        double[] b = {2};
        double[] c = {3};
        double[] d = {4};
        double res = g(a.f, b, c, d);
    }
}

In other word,is it possible to use a specific method of the object (or a static method) as a functor? If so, could you give a short example?

The functor represent an illustration of the function working with a data member (a) and some additional parameters (b, c, d )...

Answer 1

I found the following solution. Initially, the interface IFunction is created:

public interface IFunction {
   double eval(double [] a, double [] b, double [] c) ;
}

The class A remains:

 public class A {
    private double a;

    public A(double a_) {a = a_;}

    public void f(double[] b, double[] c, double[] d) {
        d[0] = a * (b[0] + c[0]);
    }
 }

However, the class B uses a function pointer:

public class B {

  public double g(IFunction funct, double[] b, double[] c, double[] d) {
    funct.eval(b, c, d);
    return d[0];
  }

  public static void main(String[] args) {
     A a = new A(1);
     double[] b = {2};
     double[] c = {3};
     double[] d = {4};

     double res = g(a::f, b,c, d);
 }

I hope it helps... Maybe,there is a better solution :-)