Merge Sort

public class MergeSort {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		 int arr[] = { 12, 11, 13, 5, 6, 7,99,87,0,2,103 };
		 
		 System.out.println("printing an array :::");
		 printArray(arr);
		 
		 sort(arr,0,arr.length-1);
		 
		 System.out.println("printing a sorted array :::");
		 printArray(arr);
	}

	
	static void printArray(int arr[])
    {
        int n = arr.length;
        for (int i = 0; i < n; ++i)
            System.out.print(arr[i] + " ");
        System.out.println();
    }
	
	public static void sort(int arr[], int startIndex, int endIndex){
		
		if(startIndex==endIndex)
			return;
		int midIndex = (startIndex+endIndex)/2;
		
		sort(arr,startIndex, midIndex);
		sort(arr,midIndex+1,endIndex);
		
		merge(arr, startIndex, midIndex, endIndex);
		
	}
	
	public static void merge(int arr[], int startIndex, int midIndex, int endIndex ){
		
		int size1 = midIndex-startIndex+1;
		int size2 = endIndex-midIndex;
		int firstPart[] = new int[size1];
		int secondPart[] = new int[size2];
		
		System.out.println("startIndex::"+startIndex+", midIndex::"+midIndex+", endIndex::"+endIndex);
		System.out.println("size1 ::"+size1);
		System.out.println("size2 ::"+size2);
		
		
		int i=0,j=0,k=0;
		
		//copy data into the array
		for(i=0;i<size1;i++){
			firstPart[i] = arr[startIndex+i];
		}

		for(j=0;j<size2;j++){
			secondPart[j]=arr[j+midIndex+1];
		}
		
		i=0;
		j=0;
		k=startIndex;
		
		System.out.println("firstPart::");
		printArray(firstPart);
		System.out.println("secondPart::");
		printArray(secondPart);
		
		
		while(i<size1 && j<size2){
			
			if(firstPart[i]<secondPart[j]){
				arr[k]=firstPart[i];
				i++;
				k++;
			} else if(firstPart[i]>=secondPart[j]){
				arr[k]=secondPart[j];
				j++;
				k++;
			}
			
		}
		
		while(i<size1){
			arr[k] = firstPart[i];
			i++;
			k++;
		}
		
		while(j<size2){
			arr[k]=secondPart[j];
			j++;
			k++;
		}
		
		System.out.println("Merget Array::");
		printArray(arr);
		
	}
}