aidanow-uni opened a new pull request, #1469:
URL: https://github.com/apache/commons-lang/pull/1469
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**Description of Issue**
The PR addresses the JIRA issue titled '[_Short-circuit operation of
firstNonBlank and
firstNonEmpty_](https://issues.apache.org/jira/browse/LANG-1656?jql=project%20%3D%20LANG%20ORDER%20BY%20created%20DESC)',
a minor feature request originally proposed by Zhengkai Wang.
The existing methods `firstNonBlank` and `firstNonEmpty` in StringUtils.java
evaluate all input strings immediately. This can lead to extra computational
overhead when some arguments are expensive to compute, such as those involving
remote API calls or database queries.
The feature request aims to introduce supplier-based variants of these
methods, which support lazy evaluation and short-circuit behaviour.
**Implementation**
To resolve this, two new methods were added to StringUtils:
1. firstNonBlankSupplier(Supplier<String>... suppliers)
- Iterates through suppliers in order
- Returns immediately once a non-blank supplier is found
2. firstNonEmptySupplier(Supplier<String>... suppliers)
- Similar to above, but checks for non-empty rather than non-blank
strings.
Introducing new methods instead of modifying existing ones ensures backward
compatibility with existing firstNonBlank and firstNonEmpty implementations. It
avoids method overloading ambiguity and also creates a clear separation between
eager and lazy variants.
**Validation and Testing**
1. Basic functionality tests
- Implemented in StringUtilsEmptyBlankTest.
- Methods `testFirstNonBlankSupplier()` and
`testFirstNonEmptySupplier()` validate:
- Correct return of the first non-blank/non-empty string.
- Handling of null inputs, empty arrays, and suppliers that return
blank or empty values.
2. Lazy evaluation tests
- `testFirstNonBlankSupplierLazyEvaluation()` and
`testFirstNonEmptySupplierLazyEvaluation()` verify short-circuit behavior using
AtomicBoolean flags.
- Confirms that once a valid result is found, subsequent suppliers are
not invoked, ensuring performance efficiency.
3. Safety guarantees
- All methods include null checks to prevent NullPointerException.
- Edge cases covered in original tests are preserved.
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