### Question:
NumberHelper { public static boolean isNumber(final String string) { try { Integer.parseInt(string); return true; } catch (NumberFormatException nfe) { return false; } } private  NumberHelper(); static int boundInteger(int toBound, IntRange range); static int boundInteger(int toBound, int minimum, int maximum); static long boundLong(long toBound, LongRange range); static long boundLong(long toBound, long minimum, long maximum); static int parseInt(final String string, final int defaultValue); static int parseInt(final String string); static int parseInt(final String string, final int defaultValue,
      final int minimum, final int maximum); static long parseLong(final String string, final long defaultValue); static long parseLong(final String string); static long parseLong(final String string, final long defaultValue,
      final long minimum, final long maximum); static boolean isNumber(final String string); static int parseIntPermissive(String numStr, int defaultValue); static float parseFloat(String numStr, float defaultValue); static double parseDouble(String numStr, double defaultValue); static double round(double value, int decimalPlaces); static int getPageStartOffset(int page, int pageSize); static int getPageStartOffset(int page, int pageSize, int maximum); static int getPageEndOffset(int page, int pageSize, int maximum); static int getPageCount(int items, int pageSize); static Double getMedian(List<Integer> values); static boolean almostEquals(double a, double b); static boolean almostEquals(double a, double b, double epsilon);  }### Answer:
@Test public void isNumber() { assertTrue(NumberHelper.isNumber("-1")); assertTrue(NumberHelper.isNumber("0")); assertTrue(NumberHelper.isNumber("1")); assertFalse(NumberHelper.isNumber("")); assertFalse(NumberHelper.isNumber("abc")); assertFalse(NumberHelper.isNumber("1abc")); }