### Question:
CrontabElement { public boolean isFixedValue() { return this.toString().matches("\\d+"); } CrontabElement(String element); @Override String toString(); @Override boolean equals(Object obj); int toInt(); long toLong(); boolean isFixedValue(); boolean isWildcard(); boolean isNotWildcard();  }### Answer:
@Test public void isFixedValue_A$String_true() throws Exception { assertTrue(new CrontabElement("5").isFixedValue()); assertTrue(new CrontabElement("54").isFixedValue()); assertTrue(new CrontabElement("999").isFixedValue()); }
@Test public void isFixedValue_A$String_false() throws Exception { assertFalse(new CrontabElement("5*").isFixedValue()); assertFalse(new CrontabElement("12/3").isFixedValue()); assertFalse(new CrontabElement("*/2").isFixedValue()); assertFalse(new CrontabElement("2,3,4*").isFixedValue()); assertFalse(new CrontabElement("").isFixedValue()); }