How do I retrivew elements of an array of unkown size in android studio?

int factors1 = 0;
         int factors12 = 0;
         StringBuilder sb = new StringBuilder();
         String value = edtCommonFact.getText().toString()
             String[] stringsNumber = value.split(",");
             Integer[] integersNumbers = new Integer[stringsNumber.length];
             for (int i = 0; i<stringsNumber.length; i++){
                 integersNumbers[i] = Integer.parseInt(stringsNumber[i]);
             }
             Arrays.sort(integersNumbers);
             for (int i = 1; i<=integersNumbers[0]; i++){
                 if (integersNumbers[0]%i == 0){
                     factors1 = i;
                     sb.append(factors1).append(" ");
              for (int j = 1; j<=integersNumbers.length; j++){
                  if (integersNumbers[j]%j == 0){
                      factors12 = j;
                      sb.append(factors12).append(" ");
                  }
              }
                     }

             }
        String result = sb.toString();
         commonFactResult.setText("Common factors are: " + result);

This line throws the exception.
if (integersNumbers[j]%j == 0){