// GenericApplier.java is a generalization of applier2.java
// with generic types.

// UnaryFun<T,S> is a generic interface declaring f as a function taking
// an input of type T and returning a value of type S.

interface UnaryFun<T,S> {
     public S f(T x); }


// Incr instantiates method f to be the increment function on Integers

class Incr implements UnaryFun<Integer,Integer> {

   public Integer f(Integer i) { return new Integer(i+1); }

} // end Incr

// IntSqrt instantiates method f to be the square root

class IntSqrt implements UnaryFun<Integer,Float> {

   public Float f(Integer i) { return new Float(Math.sqrt(i)); }

} // end IntSqrt


class Applier<T,S>  {  // Generic class

// ApplyToArray applies Q.f to the elements of A and puts the result in B.
public void ApplyToArray(UnaryFun<T,S> Q, T[] A, S[] B) {
     for (int i = 0; i < A.length; i++) B[i] = Q.f(A[i]); }
}  // end Applier
   
public class GenericApplier {

public static void main(String args[]) {
Integer A[] = new Integer[] { 1,2,3 };
Integer B[] = new Integer[3];
Float C[] = new Float[3];
Incr Inc = new Incr();
IntSqrt ISQ = new IntSqrt();
Applier<Integer,Integer> IIApp = new Applier<Integer,Integer>();
Applier<Integer,Float> IFApp = new Applier<Integer,Float>();

IIApp.ApplyToArray(Inc,A,B);
System.out.println(B[0] + " " + B[1] + " " + B[2]);
IFApp.ApplyToArray(ISQ,A,C);
System.out.println(C[0] + " " + C[1] + " " + C[2]);
} 


} // end GenericApplier