Enthuware

i answered this wrong because of the added (propably accidental) zero in the correct answer (see below) as i read it, the value declared is 1001110_00100000, which is the same as the bit pattern declared in the question, what remains is the first three characters, namely 0b0, which - as i understand from the right answer - should be 0b. So the correct answer should be or does the additional 0 after 0b has any meaning?

*propably would have answered right if it said int b = 0b1001110_00100000 in the answer pool

No, it has no meaning. It is same as if you write 20000.00 or 020000.00.

HTH,
Paul.

So both would be correct?
as well as *edit: answered my own question by trying it out. Conclusion: Both would be correct

Enthuware OCA 8 book page 67

You can use multiple underscores consecutively. You need not worry about the rules governing the usage of underscores in hexadecimal, binary, and octal number formats. Note that this is important only for the Java 6 to Java 8 Upgrade Exam (1Z0-813). The regular exam doesn’t have questions on this feature.
…
Understanding of these formats is not required for the exam and so, I will not discuss these formats any further.

What is the lastest advice on whether this information is required for OCA 8 exam (since it clearly appears in Enthuware OCA 8 Mocks) ?

It is still good to know but not required. But you need to remember that there is no guarantee because only Oracle knows all the questions. Our advice is based on the feedback that we gather from users and our trainees.