Understanding the while loop in in this program Binary addition in java -

i found solution binary addition in java , struggling understand program, not program found on internet. while loop im struggling understand. thanks

package java_excersises;        import java.util.scanner;          public class practice17 {             public static void main(string args[]) {                 long binary1, binary2;                   int = 0, remainder = 0;                   int[] sum = new int[20];                   scanner in = new scanner(system.in);                    system.out.print("input first binary number: ");                   binary1 = in.nextlong();                   system.out.print("input second binary number: ");                   binary2 = in.nextlong();                    while (binary1 != 0 || binary2 != 0)                    {                    sum[i++] = (int)((binary1 % 10 + binary2 % 10 + remainder) % 2);                    remainder = (int)((binary1 % 10 + binary2 % 10 + remainder) / 2);                    binary1 = binary1 / 10;                    binary2 = binary2 / 10;                   }                   if (remainder != 0) {                       sum[i++] = remainder;                   }                   --i;                   system.out.print("sum of 2 binary numbers: ");                   while (i >= 0) {                    system.out.print(sum[i--]);                   }                    system.out.print("\n");                    }             }