In java, how can i declare a variable inside an if lambda condition?

Question

In my code, i have a predicate method that returns i if certain conditions are met, and i need to declare a variable inside it, but the method is written in lambda, and i don't know how to do this. Here's my code:

public static Predicate<MFDWHDealExt> isAccepted() {
        MyCalendar startDate = new MyCalendar();

        return (i -> 
                i.getCompany().equals("ACCEPTED")
                && i.getDealType() == MFDealTypeEnum.AcceptedDeal              
                && i.getSettlementDate().beforeOrEqual(startDate.findDay(i.getDealDate(), 2, true))
                );
    }

i need to declare startDate (a custom date MyDate) with the value of i.getSettlementDate, otherwise the method findDay(that returns working days), because right now is null.

Answer 1

Here:

    return (i -> { 
            return i.getCompany().equals("ACCEPTED")
              && i.getDealType() == MFDealTypeEnum.AcceptedDeal              
              && i.getSettlementDate().beforeOrEqual(startDate.findDay(i.getDealDate(), 2, true))
            });

When not using the one line syntax of lambdas, like x-> 2*x, you need block braces. And you can't use that one-line syntax when you intend to declare a local variable.

See here for the official documentation!

In other words: when you want to write several statements, like actually defining a local variable, then you need these braces!

Finally: be careful what you do here. (imho) Lambda expressions should be really short and concise. When they become "more complicated" (like: they need local variables), then I suggest to not use a lambda, but to declare a real method and call that.