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.
A developer writes: String s = "Hello"; s.concat(" World"); System.out.println(s); What is the output?
Compilation fails
Why wrong: Incorrect because code compiles.
Hello World
Why wrong: Incorrect because concat result is not assigned.
Hello
Correct because concat does not modify s.
Hello World
Why wrong: Incorrect, same as A.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Hello
Option C is correct because strings in Java are immutable. The `concat()` method returns a new string but does not modify the original string `s`. Since the return value is not assigned to any variable, the original string `s` remains unchanged, so `System.out.println(s)` prints "Hello".
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.
Compilation fails
Why it's wrong here
Incorrect because code compiles.
Hello World
Why it's wrong here
Incorrect because concat result is not assigned.
Hello
Why this is correct
Correct because concat does not modify s.
Related concept
Read the scenario before looking for a memorised answer.
Hello World
Why it's wrong here
Incorrect, same as A.
Common exam traps
The trap here is that candidates often forget that strings are immutable and assume methods like `concat()` modify the original object, leading them to choose "Hello World" instead of "Hello".
Detailed technical explanation
Under the hood, `String.concat()` creates a new `String` object by copying the original string's character array and appending the argument's characters. The original string's internal `char[]` is never altered, ensuring immutability. This design allows string pooling and thread safety without synchronization, but it also means developers must explicitly assign the result to a variable to capture the concatenated value.
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
Primitives, Strings and Operators — This question tests Primitives, Strings and Operators — Read the scenario before looking for a memorised answer..
The correct answer is: Hello — Option C is correct because strings in Java are immutable. The `concat()` method returns a new string but does not modify the original string `s`. Since the return value is not assigned to any variable, the original string `s` remains unchanged, so `System.out.println(s)` prints "Hello".
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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Last reviewed: Jun 11, 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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