WritingContractsWithUEL

The Java unified expressions languages demands, that expressions are started with ${ and closed with }. See the tutorial on how to access object fields and methods.

To reference the enclosing instance of the annotated business class, use the constant this. To reference the result of the method invocation use the constant return. The following class shows an example:

class UELInsuranceCompany {

    @Contract(
            preconditions = {
                    @Clause(value = "${damage > 0}", message = "Reported damage must be positive!",
                            exception = IllegalStateException.class),
                    @Clause(value = "${damage <= this.maximumReportableDamage}", message = "We won't pay that!",
                            exception = IllegalStateException.class) },
            postconditions = {
                    @Clause(value = "${return >= 0}", message = "We won't take any more!"),
                    @Clause(value = "${return <= this.remainingMoney}", message = "We can't pay that much!") })
    public double calculateCover(final double damage) {
        // some calculations
    }

    public double getMaximumReportableDamage() {
        // some value
    }

    public double getRemainingMoney() {
        // some value
    }

}