Why Can't I Access the QName Class in Java 5 When Compiling IBM WSDL2Java Generated Code?

Understanding Access Restrictions on Libraries: A Case Study

When working with Java code, you may encounter restrictions on accessing certain classes due to limitations imposed by specific libraries (JAR files). One such scenario arises when attempting to compile Java 1.4 code created by IBM's WSDL2Java tool using Java 5.

Error Encountered:

While attempting the compilation, you may receive the following error in Eclipse:

Access restriction: The type QName is not accessible due to restriction on required library C:\Program Files\Java\jdk1.5.0_16\jre\lib\rt.jar

This error indicates that the QName class from the javax.xml.namespace package cannot be accessed due to constraints on the required rt.jar library.

Potential Solutions:

1. Recreating Stubs:

One possible solution is to recreate the stubs using WSDL2Java. This ensures that the stubs are generated specifically for the Java 5 environment and eliminates the compatibility issues.

2. Modifying Build Path Settings:

An alternative solution involves updating the build path settings in the project properties:

• Remove the JRE System Library.
• Add the JRE System Library back by selecting "Add Library" and selecting the JRE System Library.

Reasoning Behind the Solutions:

• Recreating Stubs: By manually regenerating the stubs, you ensure they are compatible with the Java 5 environment, eliminating the need for compatibility fixes.
• Modifying Build Path Settings: Removing and re-adding the JRE System Library re-orders the libraries in the build path. This can resolve conflicts where multiple classes of the same name exist in different JAR files, prioritising the correct class. To ensure a permanent solution, it's recommended to exclude JAR files that contain duplicate classes.

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