Java 8 use throws functions instead of try catch

Question

I am trying to apply a function to a list of value, if in this function the value match, It returns an MyExceptions(a custom kind of Exceptions). I a use a single value like this:

myFunctions.checkValue(myValue);

I can throws MyExceptions directly in my function declaration, but if I have a list of value, I can't use the throws but I have to use try/catch. Like this:

public void firstCheckValue(String value1,List<String> listValue) throws MyException{
        myFunctions.checkValue(value1);
        listValue.stream().forEach(p->{
        try {
            listValue.checkValue(p);
        } catch (MyException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    });
}

Why I can't use :

listValue.stream().forEach(p->myFunctions.checkValue(p));

And directly throws MyExceptions?

Is this your IDE (Intellij) telling you that you can't use "Throws" or is the compiler giving you the error directly? — Rob de Witte, Mar 11 '20 at 15:06
Because `forEach` accepts a `Consumer` argument and the `Consumer#accept` method is not capable of throwing checked exceptions. — Slaw, Mar 11 '20 at 15:23
Also, if the sole operation on your stream is `forEach` then there's no reason to create a stream; just use `listValue.forEach(...)` directly (the method is inherited from `Iterable`). It'd be even better to simply use an enhanced for loop (e.g. `for (String p : listValue) { checkValue(p); }` as then you could throw your checked exception. — Slaw, Mar 11 '20 at 15:27

score 0 · Answer 1 · answered Mar 11 '20 at 15:11

0

Try to use RuntimeException class as the parent of MyException

answered Mar 11 '20 at 15:11

Bakhtiyor Begmatov

433
5
13

I can't, MyException is in a standard library that I have implemented and it is used by other project – Liz Lamperouge Mar 12 '20 at 14:49
In that case, move this code to a new method. Inside catch block write `throw new RuntimeException(e);` With this, you can wrap you checked exception to unchecked one. Anytime you can get your original exception with the `getCause()` method of RuntimeException – Bakhtiyor Begmatov Mar 12 '20 at 17:13
My MyExceptions class it's already extending a class, Exception. – Liz Lamperouge Mar 13 '20 at 10:47

score 0 · Answer 2 · answered Mar 11 '20 at 16:13

0

I think there is a similar question How can I throw CHECKED exceptions from inside Java 8 streams?.

I think the best way is https://github.com/ahmedbaberkhan/Utility/commit/5e62034fde4b46957cca1688be856dcebd61539d.

answered Mar 11 '20 at 16:13

DQYuan

167
7

Java 8 use throws functions instead of try catch

2 Answers2