### Question:
RealValue extends Value { @Override Value greaterThan (Value v) { return new BooleanValue (mValue > v.toRealValue ().mValue); } RealValue(double value);   RealValue(String value); @Override String toString();  }### Answer:
@Test public void testGreaterThan () { assertEquals ("false", mNegativeValue.greaterThan (mNegativeValue).toString ()); assertEquals ("true", mZeroValue.greaterThan (mNegativeValue).toString ()); assertEquals ("false", mZeroValue.greaterThan (mZeroValue).toString ()); assertEquals ("true", mPositiveValue.greaterThan (mNegativeValue).toString ()); assertEquals ("true", mPositiveValue.greaterThan (mZeroValue).toString ()); assertEquals ("false", mPositiveValue.greaterThan (mPositiveValue).toString ()); }