1Z0-829 Practice Question: Handling Date, Time, Text, Numeric and Boolean Values
Which method checks if a String is empty or contains only whitespace?
⚠ Common exam trap
Candidates often think `trim().isEmpty()` is equivalent to `isBlank()`, but `trim()` only removes characters ≤ U+0020 (space), missing other Unicode whitespace that `isBlank()` correctly identifies.
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
✓
isBlank()
The `isBlank()` method, introduced in Java 11, returns `true` if the string is empty or contains only whitespace characters (as defined by `Character.isWhitespace()`). This makes it the correct and most direct way to check for blank strings, unlike older approaches that require combining multiple checks.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
isBlank()
Why this is correct
Correct: isBlank() returns true if the string is empty or contains only whitespace characters.
- ✗
length() == 0
Why it's wrong here
Incorrect: Only checks if the string is empty, not whitespace-only.
- ✗
isEmpty()
Why it's wrong here
Incorrect: isEmpty() only returns true if length is 0, not for whitespace-only strings.
- ✗
trim().isEmpty()
Why it's wrong here
Incorrect: This works but is not a direct method and is less efficient.
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