Moving all positive elements to right side (position not preserved)

import java.util.Scanner;

import java.util.ArrayList;

import java.util.*;

class LBArrayPosRightSide{

public static void main(String arg[]){

Scanner sc=new Scanner(System.in);

System.out.println("Enter the number of elements in array : ");

int n=sc.nextInt();

int arr[]=new int[n];

System.out.println("Enter elements in array : ");

for(int i=0;i<n;i++){

arr[i]=sc.nextInt();

}

int start=0;

int end=n-1;

while(start<end){

if(arr[start]>0 && arr[end]<0){

end--;

}

else if(arr[start]<0 && arr[end]>0){

int temp=0;

temp=arr[start];

arr[start]=arr[end];

arr[end]=temp;

start++;

end--;

}

else if(arr[start]>0 && arr[end]>0){

start++;

}

else{

end--;

}

}

System.out.println("New Modified array is : ");

for(int i=0;i<n;i++){

System.out.print(arr[i]+" ");

}

//here we are taking as a category of a negative number 

}

}

Time:O(n)

Space:O(1)

Concept:Double Pointers