Add annotation to a method from an Eclipse plugin

Question

I am trying to add an annotation to a method from an Eclipse plugin. I have access to the IJavaElement that represents the particular method.

What would be the best approach using Eclipse JDT for this?

Answer 1

Yes JDT can be a good approach for this problem.

The following code will give you an idea of how to accomplish the same.
(note: code not tested nor compiled)

if (javaElement instanceof IMethod) {

    // Get the compilation unit for traversing AST
    final ASTParser parser = ASTParser.newParser(AST.JLS4);
    parser.setSource(javaElement.getCompilationUnit());
    parser.setResolveBindings(true);

    final CompilationUnit compilationUnit = (CompilationUnit) parser.createAST(null);

    // Record modification - to be later written with ASTRewrite
    compilationUnit.recordModifications();

    // Get AST node for IMethod
    int methodIndex = javaElement.getCompilationUnit().getSource().indexOf(javaElement.getSource());

    ASTNode methodASTNode = NodeFinder.perform(compilationUnit.getRoot(), methodIndex, javaElement.getSource().length());

    // Create the annotation
    final NormalAnnotation newNormalAnnotation = methodASTNode.getAST().newNormalAnnotation();
    newNormalAnnotation.setTypeName(methodASTNode.getAST().newName("AnnotationTest"));

   // Add logic for writing the AST here.

}