Question 1easymultiple choice
Full question →- A
102030
Why wrong: Incorrect.
- B
3030
Correct because addition then concatenation.
- C
30
Why wrong: Incorrect.
- D
Compilation fails
Why wrong: Incorrect.
Question 21 of 509
1Z0-811 Primitives, Strings and Operators Practice Question
This 1Z0-811 practice question tests your understanding of primitives, strings and operators. 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.
What is the result of: System.out.println(10 + 20 + "30");
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
✓
3030
In Java, the '+' operator is left-associative. The expression `10 + 20 + "30"` is evaluated as `(10 + 20) + "30"`, which first performs integer addition to get `30`, then concatenates that integer with the string `"30"`, resulting in the string `"3030"`. The `System.out.println` method then prints the string `3030`.
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.
- ✗
102030
Why it's wrong here
Incorrect.
- ✓
3030
Why this is correct
Correct because addition then concatenation.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
30
Why it's wrong here
Incorrect.
- ✗
Compilation fails
Why it's wrong here
Incorrect.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume all '+' operators in a mixed expression perform string concatenation, forgetting that Java evaluates left to right and that integer addition takes precedence until a string operand is encountered.
Detailed technical explanation
How to think about this question
Under the hood, the Java compiler translates the expression using `StringBuilder` (or `StringConcatFactory` in modern Java) for string concatenation, but the order of evaluation is determined by operator precedence and associativity. The left-associativity of '+' means that `10 + 20` is evaluated first as an integer addition, and only then is the result converted to a string and concatenated with `"30"`. This behavior is critical in real-world logging or message building where mixing numbers and strings can lead to unexpected output if parentheses are not used.
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
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: 3030 — In Java, the '+' operator is left-associative. The expression `10 + 20 + "30"` is evaluated as `(10 + 20) + "30"`, which first performs integer addition to get `30`, then concatenates that integer with the string `"30"`, resulting in the string `"3030"`. The `System.out.println` method then prints the string `3030`.
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 11, 2026
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