Question

class ArrayReverse1{
public static void reverse(int[] a, int index) {
if (index >0)
{
index= index - 1; // Decrementing the index
System.out.printf("%d%n", a[index]);
reverse(a, index); // Recursive call
}
return;
}
public static void main (String args[])
{
int [] array = { 1, 2, 3, 4, 5 };
int n=array.length;
reverse(array,n); // function call
}
}

Write a generic version of the corrected recursive reverse method that could be used to print any of the following arrays (or arrays of other reference types) in reverse order.

Integer[] integerArray = {1,2,3,4,5,6};

Double[] doubleArray = {1.1, 2.2, 3.3, 4.4, 5.5, 6.6};

String[] numbers = {"one", "two", "three", "four", "five", "six"};

Will the generic version of the reverse method (part (d)) work if the array is of type int? Explain your answer.                                                                                          Both generic and non-generic methods can be overloaded. The compiler performs a matching process to determine which method to call when a method is invoked. Under what circumstances does an attempt to make a match result in a compile-time error?

Answer 1

• public class ArrayReverse1{
    public static void main(String[] args) {
          String[] names = { "hi", "you", "there" };
          Integer[] a ={1,2,3,4};
          Double[] d = {1.0,2.4,5.4};
      
          reverse(names,names.length-1);
          reverse(a,a.length-1);
          reverse(d,d.length-1);
      }
  
      public static <T> void reverse(T[] array,int i) {
          
              if(i<0){
                  System.out.println("");
                  return;
              } 
              System.out.print(array[i] + " ");
              reverse(array,i-1);
  
      }
  }

• We can not use primitive like 'int','char' or 'double' in generic parameter. We can only use classes, interfaces and user defined objects.
• Both generic and non generic type methods can be overloaded.
• During function overloading java checks function signatures as in overloading functions have same name java compiler will check of whether functions have different parameter list or not((i.e. different number of the parameters, order of the parameters, and data types of the parameters) at compile time to distinguish the methods , if two methods have the same method signature present in the same class then we will get compile time error.
• Method signature consists of method name and parameter list.