Java8 lambda predicate exception

Question

I have the follow lambda expression:

public mylambdafunction(){
Optional<MyClass> optional = Arrays.stream(myClassesValues).filter(x ->
   new String(x.bytesArray,"UTF-16LE").equalsIgnoreCase(comparationString)).findFirst();
}

Well, the method new String(x.bytesArray,” UTF-16LE”) raise the Exception UnsupportedEncodingException .

I'd like to raise the exception to the main function mylambdafunction() , somethings like:

public mylambdafunction() throws UnsupportedEncodingException{ 
....
}

Is that possible?

Answer 1

An alternative to potentially modifying a functional interface method, since you are using a well known character set, is to use the overloaded String constructor which accepts a byte[] and a Charset , but which doesn't throw UnsupportedEncodingException .

Use StandardCharsets.UTF_16LE as the Charset argument.

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Stream#filter(Predicate) expects a Predicate which provides a test(Object) method. Since this method does not declare a checked exception which is a supertype of UnsupportedEncodingException (and since UnsupportedEncodingException is itself checked), then any lambda expression whose body throws such an exception will be incompatible. Similarly, any method reference to a method that declares such an exception will also be incompatible.