GENERICS

It would be nice if we could write a single sort method that could sort the elements in an Integer array, a String array or an array of any type that supports ordering.
Java Generic methods and generic classes enable programmers to specify, with a single method declaration, a set of related methods or, with a single class declaration, a set of related types, respectively.
Generics also provide compile-time type safety that allows programmers to catch invalid types at compile time.
 
Generic Methods:
All generic method declarations have a type parameter section delimited by angle brackets (< and >) that precedes the method's return type ( < E > in the next example).
Each type parameter section contains one or more type parameters separated by commas. A type parameter, also known as a type variable, is an identifier that specifies a generic type name.
The type parameters can be used to declare the return type and act as placeholders for the types of the arguments passed to the generic method, which are known as actual type arguments.
A generic method's body is declared like that of any other method. Note that type parameters can represent only reference types not primitive types (like int, double and char).
 
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public class GenericMethodTest
    {
        // generic method printArray
        public static < E > void printArray( E[] inputArray )
            {
                // Display array elements
                for ( E element : inputArray )
                    {
                        System.out.printf( "%s ", element );
                    }
                System.out.println();
            }
        public static void main( String args[] )
            {
                // Create arrays of Integer, Double and Character
                Integer[] intArray = { 1, 2, 3, 4, 5 };
                Double[] doubleArray = { 1.1, 2.2, 3.3, 4.4 };
                Character[] charArray = { 'H', 'E', 'L', 'L', 'O' };
                System.out.println( "Array integerArray contains:" );
                printArray( intArray );
                System.out.println( "\nArray doubleArray contains:" );
                printArray( doubleArray );
                // pass a Double array
                System.out.println( "\nArray characterArray contains:" );
                printArray( charArray );
                // pass a Character array
            }
    }