Chaining Predicates

Predicates are quite powerful. They provide convenient methods like negate, and and or and hence it is easy to chain them. Here's an example.

public class PredicateMonetaryAmountMix {

    public static void main(String[] args) {
        CurrencyUnit dollar = Monetary.getCurrency("USD");
        CurrencyUnit real = Monetary.getCurrency("BRL");


        MonetaryAmount money = Money.of(10, dollar);
        MonetaryAmount money2 = Money.of(10, dollar);
        MonetaryAmount money3 = Money.of(10, dollar);
        MonetaryAmount money4 = Money.of(9, dollar);
        MonetaryAmount money5 = Money.of(8, dollar);
        MonetaryAmount money6 = Money.of(8, dollar);

        List<MonetaryAmount> greaterThanZeroAndIsReal = Stream
                .of(money, money2, money3, money4, money5, money6)
                .filter(MonetaryFunctions.isGreaterThan(Money.zero(dollar))
                        .and(MonetaryFunctions.isCurrency(real)))
                .collect(Collectors.toList());//[]

        List<MonetaryAmount> greaterThanZeroOrIsReal = Stream
                .of(money, money2, money3, money4, money5, money6)
                .filter(MonetaryFunctions.isGreaterThan(Money.zero(dollar))
                        .or(MonetaryFunctions.isCurrency(real)))
                .collect(Collectors.toList());//[USD 10, USD 10, USD 10, USD 9, USD 8, USD 8]

        List<MonetaryAmount> notGreaterThan = Stream
                .of(money, money2, money3, money4, money5, money6)
                .distinct()
                .filter(MonetaryFunctions.isGreaterThan(Money.of(9, dollar))
                        .negate())
                .collect(Collectors.toList());//[USD 9, USD 8]

    }
}