java - Java8 Lambda Function assignment with exception

Question

This question already has answers here: question from:https://stackoverflow.com/questions/65944705/java8-lambda-function-assignment-with-exception

Answer 1

I think your problem is NotFoundException is a checked exception. Checked Exceptions (not RuntimeException subclasses) can not be thrown in a lambda. A workaround is to catch it and rethrown inside a RuntimeException as its cause.

Eg:

Function<Long, ShoppingCart> func = e -> {
        try {
            return fetchCart(e);
        } catch (NotFoundException ex) {
            RuntimeException re = new RuntimeException();
             re.initCause(ex);
             throw re;
        }
        return null;
    };

Then, when you will catch the runtimeException, you will have to handle its cause.

try {
    /// call func here
} catch(Exception e) {
    ((NotFoundException)e.getCause()).printStackTrace();
}