Please help me find error in this code

#1

import java.util.*;
public class Main {
public static void main(String args[]) {
Scanner scn = new Scanner(System.in);
int T = scn.nextInt();

	for(int ia=0; ia< T; ia++){
		int n = scn.nextInt();
		long [] arr = new long[n];
		//values for array
		for(int i= 0; i< n; i++){
			arr[i] = scn.nextInt();
		}

		for(int i = 0; i< n-1 ; i++){
			for(int j = i+1; j< n; j++){
				if(strCmp(arr[i], arr[j])){
					long temp = arr[i];
					arr[i] = arr[j];
					arr[j] = temp;
				}
			}
		}
		for(int i = 0; i<n; i++)
			System.out.print(arr[i]);
		
	}
}
public static boolean strCmp(long a, long b){
	String str1 = String.valueOf(a) + String.valueOf(b);
	String str2 = String.valueOf(b) + String.valueOf(a);
	
	long ij = Long.parseLong(str1);
	long ji = Long.parseLong(str2);

	if(ij > ji){
		return false;
	}
	else{
		return true;
	}
}

}