Quick Answer
The answer is $dollar and _count. These are both valid Java identifiers because Java allows identifiers to begin with a letter, an underscore (_), or a dollar sign ($), and to contain any combination of letters, digits, underscores, or dollar signs after the first character. The Oracle Java Foundations 1Z0-811 exam frequently tests this rule to see if you know that, while underscores and dollar signs are permitted as starting characters, digits are not. A common trap is assuming identifiers cannot start with a dollar sign or underscore at all, or that they can start with a number. Remember the valid starting characters with the mnemonic "LUD" — Letter, Underscore, Dollar — and that digits can only appear after the first character.
This 1Z0-811 practice question tests your understanding of java basics and syntax. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 TWO of the following are valid Java identifiers?
class
Why wrong: Invalid. Reserved word.
2ndValue
Why wrong: Invalid. Starts with digit.
_count
Valid. Underscore is allowed.
my-var
Why wrong: Invalid. Hyphen not allowed.
$dollar
Valid. Dollar sign is allowed.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
_count
Option C (_count) is a valid Java identifier because identifiers can begin with an underscore (_) or a dollar sign ($), and can contain letters, digits, underscores, and dollar signs. Java allows underscores as the first character, though this is discouraged in modern Java style guides.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
class
Why it's wrong here
Invalid. Reserved word.
2ndValue
Why it's wrong here
Invalid. Starts with digit.
_count
Why this is correct
Valid. Underscore is allowed.
Related concept
Read the scenario before looking for a memorised answer.
my-var
Why it's wrong here
Invalid. Hyphen not allowed.
$dollar
Why this is correct
Valid. Dollar sign is allowed.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Cisco often tests the misconception that underscores and dollar signs are not valid identifier characters, or that keywords can be used as identifiers if they are not used in a keyword context, but the rule is absolute: reserved words cannot be identifiers.
Detailed technical explanation
Java identifiers are defined by the Java Language Specification (JLS §3.8) as sequences of Java letters and Java digits, where the first character must be a Java letter (which includes underscore and dollar sign). The underscore as a leading character was historically allowed but is now flagged as a warning in many IDEs because it can be confused with unused variable conventions. The dollar sign is commonly used in generated code (e.g., inner class names like Outer$Inner) but is discouraged in hand-written code.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the 1Z0-811 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
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FAQ
Java Basics and Syntax — This question tests Java Basics and Syntax — Read the scenario before looking for a memorised answer..
The correct answer is: _count — Option C (_count) is a valid Java identifier because identifiers can begin with an underscore (_) or a dollar sign ($), and can contain letters, digits, underscores, and dollar signs. Java allows underscores as the first character, though this is discouraged in modern Java style guides.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Same concept, more angles
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Which THREE are valid Java identifiers?
easyWhy B: Option B (my_value) is a valid Java identifier because it starts with a letter (m) and contains only letters, digits, and underscores. Java identifiers must begin with a letter, underscore, or dollar sign, and subsequent characters can include letters, digits, underscores, or dollar signs.
Last reviewed: Jun 25, 2026
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