### Question:
MathUtils { public static boolean isInteger(String numberString) { try { Integer.parseInt(numberString); return true; } catch (NumberFormatException ex) { return false; } }  static boolean isNumber(String numberString); static boolean isInteger(String numberString); static boolean isLong(String numberString); static int parseInt(String numberString); static long parseLong(String numberString); static double round(double sourceNum, int scale); static int castToInt(Object value); static long castToLong(Object value); static double castToDouble(Object value); static int castToIntNoException(Object value); static long castToLongNoException(Object value); static double castToDoubleNoException(Object value);  }### Answer:
@Test public void isInteger() throws Exception { Assert.assertTrue(MathUtils.isInteger("121")); Assert.assertFalse(MathUtils.isInteger("999999999999")); }