ArrayIndexOutOfBoundsException in ten's complement arithmetic implementation

Question

My code tries to implement an algorithm to

• take user input for two integer numbers and an operand + or - from the console,
• s

Answer 1

The code after fixing the problems. all thanks to @kriegaex !

import java.util.*;
public class Program9 {

  public static String getOperand() {
    Scanner scan = new Scanner(System.in);
    String stringOfInteger;
    
    System.out.print("Please enter an integer up to 50 numbers: ");
    stringOfInteger = scan.nextLine();
    return stringOfInteger;
  }

  public static int[] convert(String operand) {
    int [] integer = new int[50];
    char ch;
    
    int position = operand.length() - 1;
    for (int i = integer.length - 1; i >= 0; i--) {
      if (position >= 0)
        ch = operand.charAt(position--);
      else
        ch = 0;
      if (ch >= '0' && ch <= '9') {
        integer[i] = ch - '0';
      } else {
        integer[i] = 0;
      }
    }
    return integer;
  }

  public static int[] add(int[] operand1, int[] operand2) {
    int [] result = new int[operand1.length];
    
    int carry = 0;
    for (int i = operand1.length - 1; i >= 0; i--) {
      result[i] = operand1[i] + operand2[i] + carry;
      if (result[i] / 10 == 1) {
        result[i] = result[i] % 10;
        carry = 1;
      } else
        carry = 0;
    }
    return result;
  }

  public static int[] complement(int[] operand2){
    int [] result = new int[operand2.length];
    
    for (int i = operand2.length - 1; i >= 0; i--)
      result[i] = 9 - operand2[i];
    return result;
  }

  public static int[] add1(int[] operand2){
    int [] result = new int[operand2.length];
    
    result[operand2.length - 1] = 1;
    for (int i = result.length - 2; i >= 0; i--)
      result[i] = 0;
    return result;
  }

  public static int[] negate(int[] operand2){
    return add(add1(operand2), complement(operand2));
  }

  public static void print(int[] result, String operation) {
    if (operation.charAt(0) == '+')
      System.out.print("The subtotal of the two integers = ");
    else if (operation.charAt(0) == '-')
      System.out.print("The subtraction of the two integers = ");
    
    if (result[0] == 9) {
        result = negate(result);
        System.out.print("-");
    }
    boolean leadingZero = true;
    for (int i = 0; i < result.length; i++) {
      if (leadingZero) {
        if (result[i] == 0)
          continue;
        leadingZero = false;
      }
      System.out.print(result[i]);
    }
    if (leadingZero == true)
      System.out.println('0' - '0');
    System.out.println();
  }

  public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    int [] result = new int[50];
    String string1 = getOperand();
    String string2 = getOperand();
    int [] integer1 = convert(string1);
    int [] integer2 = convert(string2);
    String operation;
    
    System.out.print("Please enter which operation will be used (+ or -): ");
    operation = scan.nextLine();
    if (operation.charAt(0) == '+')
      add(integer1, integer2);
    else if (operation.charAt(0) == '-')
      integer2 = negate(integer2);
    
    result = add(integer1, integer2);
    
    System.out.println(Arrays.toString(integer1));
    System.out.println(Arrays.toString(integer2));
    System.out.println(Arrays.toString(add(integer1, integer2)));
    print(result, operation);
    
  }
}