Fix `IllegalCharacterException` when downloading pdfs with links having `:` by subhramit · Pull Request #14977 · JabRef/jabref

subhramit · 2026-01-31T21:28:23Z

User description

Steps to test

Try to add the entry

@InCollection{Vecino2026,
  author    = {Vecino, Sara and Acevedo-Diaz, Gloria and Fernandez-Lanvin, Daniel and Andres, Javier and Gonzalez-Rodriguez, Martin},
  booktitle = {Artificial Intelligence in Healthcare},
  publisher = {Springer},
  title     = {Early Objective ASD Screening System Based on Eye-Tracking and Machine Learning},
  year      = {2026},
  isbn      = {978-3-032-00651-6},
  month     = jan,
  abstract  = {The diagnosis of autism spectrum disorder (ASD) is still based on clinical observation, as there are no validated biomarkers for use in clinical practice. Although the first suspicions may appear as early as 12 months, the diagnosis may be delayed until 3 to 6 years. We propose an early screening procedure for autism starting at 9 months of age, which will allow paediatricians to objectively detect the presence of ASD risk indicators, facilitate immediate access to a specific preventive action program, and minimize the effects of the disorder. Our system utilizes a series of videos specifically designed to detect ASD risk indicators combined with machine learning classifiers to predict ASD risk. Using Random Forest, SVM, MLP, kNN, and AdaBoost, we obtained a 0.9005 ROC AUC, 75.2% sensitivity with the best classifier, which was SVM, when comparing typical development (TD) to ASD levels 1, 2, and 3. The results were up to a ROC AUC score of 0.9508 and a sensitivity of 87.64% with Random Forest, when comparing TD to ASD levels 2 and 3.},
  date      = {2026-01-01},
  doi       = {10.1007/978-3-032-00652-3_11},
  file      = {:http\://link.springer.com/openurl/pdf?id=doi\:10.1007/978-3-032-00652-3_11:PDF},
}

to a library.
It should add successfully now.

Before:

and the entry would not be added (or visible in the library)
Now:

Mandatory checks

I own the copyright of the code submitted and I license it under the MIT license
I manually tested my changes in running JabRef (always required)
I added JUnit tests for changes (if applicable)
I added screenshots in the PR description (if change is visible to the user)
I described the change in CHANGELOG.md in a way that is understandable for the average user (if change is visible to the user)
[/] I checked the user documentation: Is the information available and up to date? If not, I created an issue at https://github.com/JabRef/user-documentation/issues or, even better, I submitted a pull request updating file(s) in https://github.com/JabRef/user-documentation/tree/main/en.

PR Type

Bug fix

Description

Fix IllegalCharacterException when processing URLs with colons
Extract filename from URL path before getting file extension
Add tests for online links and URL path handling
Update changelog with issue reference

Diagram Walkthrough

flowchart LR
  A["LinkedFile with URL"] --> B{"Is Online Link?"}
  B -->|Yes| C["Extract filename from URL"]
  C --> D["Get file extension"]
  B -->|No| E["Get extension directly"]
  D --> F["Determine file type"]
  E --> F
  F --> G["Return ExternalFileType"]

File Walkthrough

Relevant files

Bug fix

ExternalFileTypes.java `Handle URL paths separately for extension detection` jabgui/src/main/java/org/jabref/gui/externalfiletype/ExternalFileTypes.java Added conditional logic to detect online links vs local files For URLs, extract filename first using `FileUtil.getFileNameFromUrl()` to avoid InvalidPathException For local files, get extension directly as before Prevents colon characters in URLs from causing path validation errors	+15/-2

Tests

ExternalFileTypesTest.java `Add tests for online link file type detection` jabgui/src/test/java/org/jabref/gui/externalfiletype/ExternalFileTypesTest.java Added test for online links with unknown file type Added test for URLs containing colons in the path Both tests verify correct PDF file type detection	+16/-0

Documentation

CHANGELOG.md `Document URL colon handling fix` CHANGELOG.md Added entry documenting the fix for IllegalCharacterException References issue Invalid path exception when auto-downloading linked pdf #14975 about colon characters in download links	+1/-0

Signed-off-by: subhramit <subhramit.bb@live.in>

qodo-free-for-open-source-projects · 2026-01-31T21:28:53Z

PR Compliance Guide 🔍

Below is a summary of compliance checks for this PR:

Security Compliance

🟢

No security concerns identified

No security vulnerabilities detected by AI analysis. Human verification advised for critical code.

Ticket Compliance

🟡

🎫 #14975

🟢	Fix the InvalidPathException (java.nio.file.InvalidPathException: Illegal char <:> at index 4) that occurs when auto-downloading linked PDFs with URLs containing colons
	Handle the specific case where the file field contains a URL like 'http://link.springer.com/openurl/pdf?id=doi:10.1007/978-3-032-00652-3_11'
	Allow the BibTeX entry with the problematic URL to be added successfully to the library
	Prevent the exception from occurring in FileUtil.getFileExtension when processing URLs on Windows
⚪	Display the entry correctly in the library table without throwing exceptions

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🏷️ - Compliance label

qodo-free-for-open-source-projects · 2026-01-31T21:29:57Z

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
Learned best practice	Add input validation for link path Add null/empty validation for `linkPath` before processing to prevent potential NullPointerException or unexpected behavior when `linkedFile.getLink()` returns null or empty string. jabgui/src/main/java/org/jabref/gui/externalfiletype/ExternalFileTypes.java [121-133] String linkPath = linkedFile.getLink(); +if (linkPath == null \|\| linkPath.isBlank()) { + return Optional.empty(); +} Optional<String> extensionOpt; if (linkedFile.isOnlineLink()) { // For URLs, extract filename from URL path first to avoid InvalidPathException // URLs contain ":" which is illegal in Windows file paths (e.g., "http://") // See https://github.com/JabRef/jabref/issues/14975 extensionOpt = FileUtil.getFileNameFromUrl(linkPath) .flatMap(FileUtil::getFileExtension); } else { // For local files, get extension directly extensionOpt = FileUtil.getFileExtension(linkPath); } Apply / Chat Suggestion importance[1-10]: 6 __ Why: Relevant best practice - Add input validation checks to methods that accept external data to ensure parameters are not null, empty, or invalid before processing, throwing appropriate exceptions when validation fails.	Low
General	Simplify conditional logic for conciseness Refactor the conditional logic to return directly from the `if` and `else` blocks, eliminating the intermediate `extensionOpt` variable for conciseness. jabgui/src/main/java/org/jabref/gui/externalfiletype/ExternalFileTypes.java [120-135] // No type could be found from mime type. Try based on the extension: String linkPath = linkedFile.getLink(); -Optional<String> extensionOpt; if (linkedFile.isOnlineLink()) { // For URLs, extract filename from URL path first to avoid InvalidPathException // URLs contain ":" which is illegal in Windows file paths (e.g., "http://") // See https://github.com/JabRef/jabref/issues/14975 - extensionOpt = FileUtil.getFileNameFromUrl(linkPath) - .flatMap(FileUtil::getFileExtension); + return FileUtil.getFileNameFromUrl(linkPath) + .flatMap(FileUtil::getFileExtension) + .flatMap(extension -> getExternalFileTypeByExt(extension, externalApplicationsPreferences)); } else { // For local files, get extension directly - extensionOpt = FileUtil.getFileExtension(linkPath); + return FileUtil.getFileExtension(linkPath) + .flatMap(extension -> getExternalFileTypeByExt(extension, externalApplicationsPreferences)); } -return extensionOpt.flatMap(extension -> getExternalFileTypeByExt(extension, externalApplicationsPreferences)); - Apply / Chat Suggestion importance[1-10]: 3 __ Why: The suggestion is a valid refactoring for conciseness, but it introduces code duplication by repeating the `flatMap` call, which goes against the DRY principle and may not improve readability.	Low
More

subhramit added 3 commits February 1, 2026 01:56

Extract filename from url path

f05a802

Signed-off-by: subhramit <subhramit.bb@live.in>

Add tests

ce3aec4

Signed-off-by: subhramit <subhramit.bb@live.in>

Add changelog entry

1ab899b

Signed-off-by: subhramit <subhramit.bb@live.in>

qodo-free-for-open-source-projects Bot added the Review effort 2/5 label Jan 31, 2026

Merge branch 'main' into illega-paths

3dbba90

subhramit mentioned this pull request Jan 31, 2026

CSLStyle references with unusual bibtexkeys do not show up in LibreOffice #14961

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subhramit added the status: ready-for-review Pull Requests that are ready to be reviewed by the maintainers label Jan 31, 2026

subhramit changed the title ~~Extract filename from url path~~ Fix IllegalCharacterException when downloading pdfs with links having : Jan 31, 2026

subhramit added the component: external-files label Jan 31, 2026

Siedlerchr approved these changes Jan 31, 2026

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Siedlerchr enabled auto-merge January 31, 2026 21:43

Siedlerchr added this pull request to the merge queue Jan 31, 2026

github-actions Bot added the status: to-be-merged PRs which are accepted and should go into the merge-queue. label Jan 31, 2026

Merged via the queue into JabRef:main with commit b243b20 Jan 31, 2026
67 of 82 checks passed

Siedlerchr deleted the illega-paths branch January 31, 2026 22:19

github-actions Bot mentioned this pull request Jan 31, 2026

Invalid path exception when auto-downloading linked pdf #14975

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Fix `IllegalCharacterException` when downloading pdfs with links having `:`#14977

Fix `IllegalCharacterException` when downloading pdfs with links having `:`#14977
Siedlerchr merged 4 commits into
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subhramit:illega-paths

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