[insaf021]

Observed on master with the default formats:

new ComplexFormat().parse("2i")     -> (2.0, 0.0)
new ComplexFormat().parse("1x")     -> (1.0, 0.0)
new ComplexFormat().parse("1 +")    -> (1.0, 0.0)
new RealMatrixFormat().parse("{{1}") -> Array2DRowRealMatrix{{1.0}}

Malformed input is accepted here and becomes a wrong value instead of a MathParseException.

The root cause is two end-of-input mistakes in the CompositeFormat cursor helpers. parseNextCharacter decides whether it found a character by testing index < n after the post-increment, so a non-whitespace character in the last position is consumed but reported as 0, which ComplexFormat reads as "no imaginary part". parseAndIgnoreWhitespace always rewinds by one, so at end of input it steps back onto the previous character; in RealMatrixFormat the row suffix } is then matched a second time as the matrix suffix.

The fix tests the character itself in parseNextCharacter and rewinds only when something was consumed. parseFixedstring previously refused any literal at end of input, and formats with an empty suffix only parsed because of the bogus rewind, so it now lets an empty literal match there. Existing error indices (e.g. testForgottenSuffix) are unchanged. This is separate from #326, which fixed special-value matching in parseNumber.

Regression tests are in ComplexFormatAbstractTest and RealMatrixFormatAbstractTest and fail without the patch. mvn -pl commons-math-legacy passes on JDK 21 (checkstyle, PMD, SpotBugs, tests).

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.22%. Comparing base (f554608) to head (6ebdc5a).
⚠️ Report is 391 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #338      +/-   ##
============================================
+ Coverage     86.54%   87.22%   +0.68%     
+ Complexity     9787       91    -9696     
============================================
  Files           532      499      -33     
  Lines         35516    33519    -1997     
  Branches       6194     5848     -346     
============================================
- Hits          30738    29238    -1500     
+ Misses         3518     3162     -356     
+ Partials       1260     1119     -141     

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