Java Index Array out of Bounds Error for partitioning method. The left pointer seems to be going out of bounds but I can

[answerhappygod]

Java Index Array out of Bounds Error for partitioning method.
The left pointer seems to be going out of bounds but I cant figure
out how to fix it.
import java.io.*;
public class Tester {
static int ran = 93;
public static void main(String[] args) throws IOException {
int[] num = new int[50];
int[] numSave = new int[50];
for (int n = 10; n <= 20; n += 10) {
fillRandom(num, n);
for (int i = 0; i < n; i++) {
numSave = num;
}
System.out.print(" Given array. ");
printArray(numSave, n);
for (int j = 0; j < n; j++) {
for (int i = 0; i < n; i++) {
num = numSave;
}
System.out.print(" pivot: ");
if (num[j] < 10)
System.out.print(" ");
System.out.print(num[j] + " ");
PartitionMethods.partition(num, 0, n - 1, j); //calls
partition
printArray(num, n);
}
System.out.println();
}
System.out.println();
}
public static void fillRandom(int a[], int n) {
for (int i = 0; i < n; i++) {
ran = (ran * 101 + 103) % 1000003;
a = ran / 20000;
}
}
public static void printArray(int a[], int n) {
for (int i = 0; i < n; i++) {
if (a < 10)
System.out.print(" ");
System.out.print(a + " ");
}
System.out.println();
}
}
class PartitionMethods
{
public static void swap(int a[],int i, int j)
{

int temp = a; //method
for swaps
a = a[j];
a[j] = temp;
}

public static int partition(int a[], int start, int end, int
pivot) //left pointer for this one is
messed
{
swap(a, start, pivot); //swap pivot to
start
pivot = start;

int LFPntr = start+1; // lfpt is at
index 1, after the pivot
int RTPntr = end; // rtpt
is at the end of the array
while(LFPntr < RTPntr)
{
while(a[RTPntr]
> a[pivot])
{ // if RTPT is larger
than pivot, move pointer down

RTPntr--;
}
while(a[LFPntr] <
a[pivot])
{ //if LFPT is smaller
than pivot, move pointer up

LFPntr++;

}
if(start <=
end)

swap(a,LFPntr, RTPntr);
}
if (a[RTPntr]<a[pivot])
//swaps the pivot back into correct place
{

swap(a,pivot,RTPntr);
pivot = RTPntr;


}
else
{

swap(a,pivot,RTPntr+1);
pivot = RTPntr+1;
}
return pivot;
}
}