[JEP 511] Module Import Declarations by johannescoetzee · Pull Request #4905 · javaparser/javaparser

johannescoetzee · 2025-11-24T15:19:22Z

This PR adds parser support for module import statements, as well as support for resolving types from modules.

Changes to ImportDeclaration/CompilationUnit

Constructors and an addImport method with an option to specify whether this is a module import or not (indicated by the value of the new isModule field in ImportDeclaration) were added. The old versions of these constructors and this method without the isModule parameter were kept to avoid breaking user code.

JarTypeSolver

Javassist does not provide much support for handling modules, so I ended up parsing the module attribute manually. This is a bit cumbersome, but does work and I hope the comments explain what is happening sufficiently well.

ClassLoaderTypeSolver

I couldn't figure out a way to do this without using Java 9+ types and methods, so I used a lot of reflection for the implementation to maintain compatibility with Java 8 (although this will always fail if JavaParser is run with Java 8). I also couldn't figure out a good way to get to a list of modules loaded by a classloader (the mechanisms I could find that looked promising were all JDK-internal or blocked for security reasons). The solution as it is presented here requires users to provide a list of module layers that the typesolver will use to find modules. This is done automatically for the ReflectionTypeSolver.

…odegen

… and ClassLoaderTypeSolver

codecov · 2025-11-24T15:30:02Z

Codecov Report

❌ Patch coverage is 63.21244% with 71 lines in your changes missing coverage. Please review.
✅ Project coverage is 58.394%. Comparing base (f3f0f33) to head (b228a3c).
⚠️ Report is 11 commits behind head on master.

Files with missing lines	Patch %	Lines
...ver/resolution/typesolvers/CombinedTypeSolver.java	29.166%	14 Missing and 3 partials ⚠️
.../resolution/typesolvers/ClassLoaderTypeSolver.java	59.459%	9 Missing and 6 partials ⚠️
...r/resolution/typesolvers/JavaParserTypeSolver.java	64.516%	6 Missing and 5 partials ⚠️
...olsolver/resolution/typesolvers/JarTypeSolver.java	81.818%	4 Missing and 4 partials ⚠️
...a/com/github/javaparser/resolution/TypeSolver.java	0.000%	5 Missing ⚠️
...a/com/github/javaparser/ast/ImportDeclaration.java	77.777%	4 Missing ⚠️
...ava/com/github/javaparser/ast/CompilationUnit.java	60.000%	1 Missing and 1 partial ⚠️
...om/github/javaparser/ast/visitor/CloneVisitor.java	0.000%	2 Missing ⚠️
...m/github/javaparser/ast/visitor/EqualsVisitor.java	0.000%	0 Missing and 1 partial ⚠️
...github/javaparser/ast/visitor/HashCodeVisitor.java	0.000%	0 Missing and 1 partial ⚠️
... and 5 more

Additional details and impacted files

@@               Coverage Diff               @@
##              master     #4905       +/-   ##
===============================================
+ Coverage     58.368%   58.394%   +0.026%     
- Complexity      2534      2555       +21     
===============================================
  Files            681       681               
  Lines          39302     39490      +188     
  Branches        7134      7163       +29     
===============================================
+ Hits           22940     23060      +120     
- Misses         13448     13493       +45     
- Partials        2914      2937       +23

Flag	Coverage Δ
AlsoSlowTests	`58.394% <63.212%> (+0.026%)`	⬆️
javaparser-core	`58.394% <63.212%> (+0.026%)`	⬆️
javaparser-symbol-solver	`58.394% <63.212%> (+0.026%)`	⬆️
jdk-10	`57.962% <62.694%> (+0.028%)`	⬆️
jdk-11	`57.961% <62.694%> (+0.025%)`	⬆️
jdk-12	`57.959% <62.694%> (+0.022%)`	⬆️
jdk-13	`57.961% <62.694%> (+0.025%)`	⬆️
jdk-14	`58.194% <62.694%> (+0.021%)`	⬆️
jdk-15	`58.197% <62.694%> (+0.026%)`	⬆️
jdk-16	`58.172% <62.694%> (+0.024%)`	⬆️
jdk-17	`58.324% <62.694%> (+0.023%)`	⬆️
jdk-18	`58.324% <62.694%> (+0.023%)`	⬆️
jdk-8	`57.813% <33.160%> (-0.124%)`	⬇️
jdk-9	`57.960% <62.694%> (+0.028%)`	⬆️
macos-latest	`58.386% <63.212%> (+0.026%)`	⬆️
ubuntu-latest	`58.381% <63.212%> (+0.026%)`	⬆️
windows-latest	`58.376% <63.212%> (+0.026%)`	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...ub/javaparser/ast/observer/ObservableProperty.java	`87.027% <100.000%> (ø)`
...vaparser/metamodel/ImportDeclarationMetaModel.java	`100.000% <ø> (ø)`
...thub/javaparser/metamodel/JavaParserMetaModel.java	`99.708% <100.000%> (+0.001%)`	⬆️
...r/resolution/typesolvers/ReflectionTypeSolver.java	`100.000% <100.000%> (ø)`
...m/github/javaparser/ast/visitor/EqualsVisitor.java	`23.076% <0.000%> (-0.039%)`	⬇️
...github/javaparser/ast/visitor/HashCodeVisitor.java	`60.975% <0.000%> (-0.166%)`	⬇️
...javaparser/ast/visitor/NoCommentEqualsVisitor.java	`4.862% <0.000%> (-0.011%)`	⬇️
...vaparser/ast/visitor/NoCommentHashCodeVisitor.java	`78.400% <0.000%> (-0.315%)`	⬇️
...vaparsermodel/contexts/CompilationUnitContext.java	`82.323% <85.714%> (+0.124%)`	⬆️
...olsolver/resolution/typesolvers/AarTypeSolver.java	`77.777% <0.000%> (-4.576%)`	⬇️
... and 9 more

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johannescoetzee · 2025-11-27T15:58:32Z

I realised while reviewing #4902 that I forgot the validator and printer support for this. I'm closing this for now and will re-open it once that's done.

jlerbsc · 2025-11-28T10:02:00Z

+                continue;
+            }
+            try {
+                /* This code is equivalent to the snippet below, but is done with reflection to maintain compatibility


Can you isolate this code in a class that could be called, for example, ModuleLayerHelper?

jlerbsc · 2025-11-28T10:03:51Z

@@ -68,17 +121,24 @@ protected boolean filterName(String name) {
    @Override
    public SymbolReference<ResolvedReferenceTypeDeclaration> tryToSolveTypeInModule(String qualifiedModuleName, String simpleTypeName) {


Is it really necessary to create a new method to handle this particular case?

A new method may not be the only solution, but we do need to keep track of the fact that we want to solve the type in a module, as well as the name of the module. This is not information that is currently tracked with the regular solveType methods. Since we know exactly when solving a type in a module is needed (that only being when handling module imports), I think a separate method is a much cleaner approach than trying to modify the already complex solveType structure/API to record the information we need, while also greatly reducing the risk of introducing new bugs into existing resolution logic.

A new method may not be the only solution, but we do need to keep track of the fact that we want to solve the type in a module, as well as the name of the module. This is not information that is currently tracked with the regular solveType methods. Since we know exactly when solving a type in a module is needed (that only being when handling module imports), I think a separate method is a much cleaner approach than trying to modify the already complex solveType structure/API to record the information we need, while also greatly reducing the risk of introducing new bugs into existing resolution logic.

I do understand the concerns raised. I was thinking of scanning all modules for the class declaration, but that wouldn't be very efficient.

jlerbsc · 2025-11-28T10:08:03Z

+
+        HashSet<Object> moduleLayers = new HashSet<>();
+        try {
+            /* This code is equivalent to the snippet below, but is done with reflection to maintain compatibility with


Probably to be declared in a ‘ModuleLayerHelper’ class.

jlerbsc · 2025-11-28T10:13:10Z


                return SymbolReference.unsolved();
            }
+


To make the PRs easier to read, would it be possible to isolate the JP test cases in a single commit, and also isolate the code generated by JP, which is specific to printers, the features of the symbol resolver, and the tests which are specific to symbol resolvers?

jlerbsc · 2025-11-28T13:15:19Z

        }
    }

+    private void registerModuleInfo() {


This code could be externalised into a helper class until the Javassist project offers this functionality.
Perhaps we could either report an issue or make a contribution to the project.

I think creating an issue is a good idea just to get an idea of whether this is something they would be interested in. The implementation here is very specific to what we need, so a more general approach would require some thought and could lead to some questions about attribute handling in javassist in general, which may be beyond the scope of what they want to do. I'll collect my thoughts on the issue and ask them about it

jlerbsc · 2025-11-28T13:21:42Z

                 * }
                 */
-                Set<Object> modulesSet = (Set<Object>) moduleLayer.getClass().getMethod("modules").invoke(moduleLayer);
+                Set<Object> modulesSet = (Set<Object>)


To outsource.

jlerbsc · 2025-11-28T13:23:47Z

    }
+
+    @Test
+    void testJavaModuleImportFromSource() {


@EnabledForJreRange ?

jlerbsc · 2025-11-28T13:27:23Z

+
+    @BeforeEach
+    void setup() throws IOException {
+        Path pathToJar = adaptPath("src/test/resources/modules/moduletest/com-github-javaparser-testmodule.jar");


Can you delete the directory "moduletest" from the path?

jlerbsc · 2025-11-28T13:33:20Z

Thank you for this PR. I have a few comments and I have noted that you have other points to consider.

johannescoetzee · 2025-12-02T10:22:47Z

I opened #4910 with the changes requested here. I could not reopen this PR since I force pushed changes

johannescoetzee and others added 7 commits November 24, 2025 15:29

Add isModule field to ImportDeclaration with constructor update and c…

d32079d

…odegen

Add module import tests

9aa4570

Add solveTypeInModule to TypeSolver with implementation in Reflection…

aa3e930

… and ClassLoaderTypeSolver

Add JarTypeSolver support for module imports

7203b41

Add JavaParserTypeSolver support for module imports

48940fc

Add tests with resources

749eac6

Add module resolution support for AarTypeSolver

b228a3c

johannescoetzee mentioned this pull request Nov 25, 2025

Implement JEP 512: Compact Source Files and Instance Main Methods #4902

Closed

johannescoetzee marked this pull request as draft November 27, 2025 15:57

johannescoetzee closed this Nov 27, 2025

jlerbsc reviewed Nov 28, 2025

View reviewed changes

johannescoetzee mentioned this pull request Dec 2, 2025

[JEP 511] Module Import Declarations #4910

Merged

		@@ -68,17 +121,24 @@ protected boolean filterName(String name) {
		@Override
		public SymbolReference<ResolvedReferenceTypeDeclaration> tryToSolveTypeInModule(String qualifiedModuleName, String simpleTypeName) {

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johannescoetzee commented Nov 24, 2025

Changes to ImportDeclaration/CompilationUnit

JarTypeSolver

ClassLoaderTypeSolver

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johannescoetzee commented Dec 2, 2025

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