Question 124 of 481
1Z0-811 Object-Oriented Programming Practice Question
A junior developer writes a method that attempts to modify a String: public void update() { String s = "Hello"; s.concat(" World"); System.out.println(s); } What will be printed when update() is called?
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
✓
Hello
Strings are immutable in Java. The concat() method returns a new String but the original object remains unchanged because the result is not assigned.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Hello World
Why it's wrong here
concat() returns a new String, but the result is not assigned to s, so s remains "Hello".
- ✗
Hello World (no space)
Why it's wrong here
The concat method does add the space, but the original string is unchanged.
- ✗
Compilation error
Why it's wrong here
The code compiles fine; it just doesn't update s.
- ✓
Hello
Why this is correct
Correct. Strings are immutable; concat() does not modify the original string.
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Last reviewed: Jun 23, 2026
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