Partitioning example in core java

Partitioning: 

Partitioning is the underlying mechanism of quick sort.It is also useful operation on its own.To partitioning data is to divide it into two  groups so that the items with a key value higher than a specified amount are in one group and all the items with a lower key value are in another.

Code Example:

/**
 * @author Abhinaw.Tripathi
 *
 */

class ArrayPar
{
private long[] theArray;
private int nElems;
public ArrayPar(int max)
{
theArray =new long[max];
nElems=0;
}

public void insert(long values)
{
theArray[nElems] =values;
nElems++;
}

public int size()
{
return nElems;
}

public void display()
{
System.out.println("A=");
for(int j=0;j<nElems; j++)
System.out.println(theArray[j]+ " ");
System.out.println(" ");
}

public void swap(int dex1,int dex2)
{
long temp;
temp=theArray[dex1];
theArray[dex1]=theArray[dex2];
theArray[dex2]=temp;
}

public int partitionIt(int left,int right,long pivot)
{
int leftptr=left-1;
int rightPtr=right+1;
while(true)
{
while(leftptr <right && theArray[++leftptr] <pivot);
while(rightPtr>left && theArray[--rightPtr] > pivot);
if(leftptr >=rightPtr)
break;
else
swap(leftptr, rightPtr);
}
return leftptr;
}

}

public class PartitionApp {

public static void main(String[] args)
{
ArrayPar arr=new ArrayPar(16);
for(int j=0;j<10;j++)
{
long n=(int)(java.lang.Math.random()*99);
arr.insert(n);

}
arr.display();
long pivot=71;
System.out.println("Pivot is :"+pivot);
int size=arr.size();

int partDex=arr.partitionIt(0, size-1, pivot);

System.out.println("partition is at the index"+partDex);
arr.display();

}


}

Efficiency of the Partition Algorithm:

It runs in O(N) time