MERGE SORT PROGRAM IN JAVA

  class Mergesort_Algorithm  
 {  
     public void mergesort(int a[],int low, int upper)  
     {  
         if (low==upper)  
         {  
             return;  
         }  
         else  
         {  
             int mid=(low+upper)/2;  
             mergesort(a,low,mid);  
             mergesort(a,mid+1,upper);  
             merge(a,low,mid+1,upper);  
         }  
     }  
     public void merge(int a[],int low, int high, int upper)  
     {  
         int lower_start=low;  
         int lower_bound=high-1;  
         int upper_start=high;  
         int upper_bound=upper;  
         int n=upper-low+1;  
         int i=0;  
         int sArray[]=new int[n];  
         while ((lower_start <=lower_bound) && (upper_start<=upper_bound ))  
         {  
             if (a[lower_start]<a[upper_start])  
             {  
                 sArray[i]=a[lower_start++];  
                 i++;  
             }  
             else  
             {  
                 sArray[i]=a[upper_start++];  
                 i++;  
             }  
         }  
         while (lower_start <=lower_bound)  
         {  
             sArray[i]=a[lower_start++];  
             i++;  
         }  
         while (upper_start<=upper_bound )  
         {  
             sArray[i]=a[upper_start++];  
             i++;  
         }  
         for (i=0;i<n;i++)  
         {  
             //System.out.println("-----"+(lower_start-1));  
             a[low+i]=sArray[i];              
         }  
     }  
 }  
 class Merge  
 {  
     public static void main(String[] args)  
     {  
         Mergesort_Algorithm obj=new Mergesort_Algorithm();  
         int a[] = {2,4,5,9,0,1,7,8,10,6};  
         //Printing the Given Array.......  
         System.out.println("Given Array Before Sorting!....");  
         for(int i=0; i<a.length; i++)  
         {  
             System.out.print(a[i]+" ");  
         }  
         System.out.println();  
         obj.mergesort(a, 0, a.length-1);  
         System.out.println("Given Array Before Sorting!....");  
         for(int i=0; i<a.length; i++)  
         {  
             System.out.print(a[i]+" ");  
         }  
         System.out.println();  
         //System.out.println("Hello World!");  
     }  
 }