unordered-list

2. Common runtime errors and fixes

&]:pl-6” data-streamdown=“unordered-list”>
• Error: “java.lang.UnsatisfiedLinkError: no jni4net in java.library.path”
  • Cause: JVM cannot find the JNI4Net native bridge.
  • Fixes: Put the native DLL/SO in a directory on java.library.path or set -Djava.library.path=/path/to/lib; on Windows, ensure DLL is on PATH.
• Error: “System.DllNotFoundException: jni4net.n” or similar from .NET
  • Cause: .NET cannot load the native JNI4Net binary or dependent runtime libraries are missing.
  • Fixes: Ensure the native DLL is present and matches process bitness; install required VC++ redistributable if needed.
• Error: “java.lang.ClassNotFoundException” for your Java class when called from .NET
  • Cause: JVM classpath lacks your jars.
  • Fix: Add jars to the classpath when creating the JVM instance or configure BridgeSetup.AddAllJarsClassPath and Bridge.CreateJVM with correct paths.
• Error: “TypeLoadException” or “Method not found” in .NET proxies
  • Cause: Proxy assemblies out of sync with Java classes (method signatures changed).
  • Fix: Regenerate proxies with jni4net tools (proxygen) and rebuild .NET assemblies.
• Error: “AccessViolationException” or process crash
  • Cause: Native interop mismatch, incorrect memory handling, or mixed bitness.
  • Fixes: Confirm both runtimes match bitness, use latest stable JNI4Net native binaries, and run under a debugger to capture stack traces.

3. Initialization and shutdown issues

• Symptom: JVM won’t start or hangs during Bridge.CreateJVM
  • Check for conflicting JVMs on PATH or duplicate JVM initialization. Only one JVM instance per process is supported.
  • Use verbose JVM options (-verbose:class, -Xcheck:jni) to gain insight.
• Symptom: .NET app crashes when JVM is disposed
  • Ensure proper sequencing: avoid using Java objects after Bridge.Dispose(); prefer application-wide JVM lifetime.

4. Proxy generation best practices

• Always regenerate proxies after changing Java code.
• Use BridgeSetup to explicitly add jar paths and set classpath priorities.
• Keep proxy generation and build scripts automated (e.g., MSBuild or Gradle tasks) to prevent mismatches.

5. Version compatibility and deployment tips

• Lock JNI4Net version across development and deployment. Test on target OS/architecture.
• Bundle the correct native binaries with your deployment and set PATH/java.library.path at runtime.
• For CI/CD, include proxy generation as a build step and run smoke tests that instantiate the bridge.

6. Diagnostic checklist

1. Confirm JVM and .NET bitness match.
2. Verify native bridge DLL/SO is discoverable (PATH / java.library.path / LD_LIBRARYPATH).
3. Ensure classpath and assembly paths include all required jars and DLLs.
4. Regenerate proxies after Java changes.
5. Run with verbose JVM and .NET logging; capture stack traces.
6. Test with minimal sample that only starts the bridge and calls a simple method.

Following these checks and fixes resolves most JNI4Net integration problems. If a particular error persists, provide the exact message and environment details for targeted troubleshooting.