Question 1mediummultiple choice
Full question →- A
2variable
Why wrong: Cannot start with digit.
- B
class
Why wrong: Reserved keyword.
- C
_myVar
Underscore allowed.
- D
my-var
Why wrong: Hyphen not allowed.
Question 444 of 509
Quick Answer
The answer is _myVar, a valid Java identifier because it begins with an underscore, which the Java Language Specification explicitly permits alongside letters and the dollar sign. Java identifiers must start with a letter (A-Z, a-z), $, or _, and cannot begin with a digit or contain hyphens or spaces; _myVar satisfies all these rules. On the Oracle Java Foundations 1Z0-811 exam, this concept tests your grasp of fundamental naming conventions, often appearing in multiple-choice questions that mix valid and invalid identifiers to catch careless mistakes. A common trap is assuming underscores are outdated or disallowed, but they remain fully legal—though starting with a letter is best practice. Another trick is confusing hyphens with underscores, as hyphens are never allowed. For a quick memory tip: remember the three legal starters—Letters, Dollar, Underscore—or the mnemonic "LDU" to recall what can lead a valid identifier.
1Z0-811 Primitives, Strings and Operators Practice Question
This 1Z0-811 practice question tests your understanding of primitives, strings and operators. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which of the following is a valid Java identifier?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
_myVar
Option C (_myVar) is a valid Java identifier because it starts with an underscore, which is permitted by the Java Language Specification. Java identifiers must begin with a letter (A-Z, a-z), dollar sign ($), or underscore (_), and cannot start with a digit or contain hyphens. The underscore is explicitly allowed, making _myVar a legal identifier.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
2variable
Why it's wrong here
Cannot start with digit.
- ✗
class
Why it's wrong here
Reserved keyword.
- ✓
_myVar
Why this is correct
Underscore allowed.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
my-var
Why it's wrong here
Hyphen not allowed.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Oracle often tests the rule that identifiers cannot start with a digit, but the trap here is that candidates may mistakenly think underscores are invalid or that keywords like 'class' can be used as identifiers if they forget Java's reserved word list.
Trap categories for this question
Keyword trap
Reserved keyword.
Detailed technical explanation
How to think about this question
Java identifiers are case-sensitive and can be of any length, but they must follow the Unicode-based rules defined in JLS Section 3.8. While underscores are valid, starting an identifier with an underscore is discouraged in modern Java (since Java 9) as it may be reserved for future use, but it remains syntactically legal. In real-world code, identifiers like _myVar are sometimes used for internal or temporary variables, but developers typically avoid leading underscores to prevent confusion with generated code or special naming conventions.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
What to study next
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FAQ
Questions learners often ask
What does this 1Z0-811 question test?
Primitives, Strings and Operators — This question tests Primitives, Strings and Operators — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: _myVar — Option C (_myVar) is a valid Java identifier because it starts with an underscore, which is permitted by the Java Language Specification. Java identifiers must begin with a letter (A-Z, a-z), dollar sign ($), or underscore (_), and cannot start with a digit or contain hyphens. The underscore is explicitly allowed, making _myVar a legal identifier.
What should I do if I get this 1Z0-811 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This 1Z0-811 practice question is part of Courseiva's free Oracle certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 1Z0-811 exam.
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