Program:

// GeneralizedMergeSort.java
public class GeneralizedMergeSort
{
	public static void sort(Comparable[] arr, int be, int en)
	{
		if((en - be) >= 1)
		{
			int splPt = split(arr, be, en);
			sort(arr, be, splPt);
			sort(arr, splPt + 1, en);
			join(arr, be, splPt, en);
		}
	}

	private static int split(Comparable[] arr, int be, int en)
	{
		return ((be + en) / 2);
	}

	private static void join(Comparable[] arr, int be, int splPt, int en)
	{
		int splitSize = (en - be + 1);
		Comparable[] tempArr = new Comparable[splitSize];
		int nextLeft = be;
		int nextRight = splPt + 1;
		int i = 0;

		while((nextLeft <= splPt) && (nextRight <= en))
		{
			if(arr[nextLeft].compareTo(arr[nextRight]) < 0)
			{
				tempArr[i] = arr[nextLeft];
				i++;
				nextLeft++;
			}

			else
			{
				tempArr[i] = arr[nextRight];
				i++;
				nextRight++;
			}
		}

		while(nextLeft <= splPt)
		{
			tempArr[i] = arr[nextLeft];
			i++;
			nextLeft++;
		}

		while(nextRight <= en)
		{
			tempArr[i] = arr[nextRight];
			i++;
			nextRight++;
		}

		for(i = 0; i < splitSize; i++)
		{
			arr[be + i] = tempArr[i];
		}
	}
}

// TestGeneralizedMergeSort.java
public class TestGeneralizedMergeSort
{
	public static void main(String[] args)
	{
		Double[] doubles = new Double[6];
		doubles[0] = 369.0;
		doubles[1] = 891.0;
		doubles[2] = 591.0;
		doubles[3] = 753.0;
		doubles[4] = 214.0;
		doubles[5] = 435.0;

		System.out.println("Double values before sorting:");
		printArray(doubles);

		GeneralizedMergeSort.sort(doubles, 0, doubles.length - 1);

		System.out.println("\nDouble values after sorting:");
		printArray(doubles);

		String[] strings = new String[6];
		strings[0] = "Plate";
		strings[1] = "Bucket";
		strings[2] = "Shampoo";
		strings[3] = "Bag";
		strings[4] = "Apples";
		strings[5] = "Mobile";

		System.out.println("\n\nString values before sorting:");
		printArray(strings);

		GeneralizedMergeSort.sort(strings, 0, strings.length - 1);

		System.out.println("\nString values after sorting:");
		printArray(strings);

	}

	public static void printArray(Comparable[] arr)
	{
		for(int i = 0; i < arr.length; i++)
		{
			System.out.print(arr[i]);

			if(i != arr.length - 1)
				System.out.print(", ");
		}
		System.out.println();
	}
}

Output:

Double values before sorting:
369.0, 891.0, 591.0, 753.0, 214.0, 435.0

Double values after sorting:
214.0, 369.0, 435.0, 591.0, 753.0, 891.0


String values before sorting:
Plate, Bucket, Shampoo, Bag, Apples, Mobile

String values after sorting:
Apples, Bag, Bucket, Mobile, Plate, Shampoo