Java Programming 1) Generics and Wildcards 1.Write a static generic method calle
ID: 3710784 • Letter: J
Question
Java Programming
1) Generics and Wildcards
1.Write a static generic method called swapPlaces that swaps the position of two elements in an array. This method should take in an array of a generic type (Object and all subclasses) and two int values to represent the array positions to swap (no need to perform error checking – although in a real application, you definitely should!)
2.Create a method that overloads the method created in (1.1). This overloaded method should take an array of Number (and any subclasses).
3.Create a method that overloads the method created in (1.1). This overloaded method should take an array of Integer (and any subclasses)
Explanation / Answer
class Solution
{
// generic method
public static <E> void swapPlaces(E[] arr, int i, int j)
{
// swap elements at position i and j
E temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
// overloaded Number class method
public static void swapPlaces(Number[] arr, int i, int j)
{
// swap elements at position i and j
Number temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
// overloaded integer method
public static void swapPlaces(int[] arr, int i, int j)
{
// swap elements at position i and j
Integer temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
public static void main(String[] args)
{
int i;
int[] arr = { 0 , 1 , 2 , 3 , 4 , 5 };
System.out.print("arr1 : ");
for( i = 0 ; i < arr.length ; i++ )
System.out.print(arr[i] + " ");
System.out.println();
swapPlaces( arr, 2 , 5 );
System.out.print(" arr1 after swapping places at 2 and 5 : ");
for( i = 0 ; i < arr.length ; i++ )
System.out.print(arr[i] + " ");
System.out.println();
}
}
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