Java毫秒转时分秒

import java.util.Scanner;

public class test {
    public static void main ( String[] args ) {
        Scanner input = new Scanner( System.in );
        long n = input.nextLong( );
        System.out.println( convertMillis( n ) );
    }

    private static String convertMillis ( long n ) {
        long a = n / ( 1000 * 60 * 60 );
        long b = n % ( 1000 * 60 * 60 ) / ( 1000 * 60 );
        long c = n % ( 1000 * 60 * 60 ) / 1000;
        return ( a + ":" + b + ":" + c );
    }
}