How to hide warning “Illegal reflective access” in java 9 without JVM argument?

by

There are ways to disable illegal access warning, though I do not recommend doing this.

1. Simple approach

Since the warning is printed to the default error stream, you can simply close this stream and redirect stderr to stdout.

public static void disableWarning() {
    System.err.close();
    System.setErr(System.out);
}

Notes:

  • This approach merges error and output streams. That may not be desirable in some cases.
  • You cannot redirect warning message just by calling System.setErr, since the reference to error stream is saved in IllegalAccessLogger.warningStream field early at JVM bootstrap.

2. Complicated approach without changing stderr

A good news is that sun.misc.Unsafe can be still accessed in JDK 9 without warnings. The solution is to reset internal IllegalAccessLogger with the help of Unsafe API.

public static void disableWarning() {
    try {
        Field theUnsafe = Unsafe.class.getDeclaredField("theUnsafe");
        theUnsafe.setAccessible(true);
        Unsafe u = (Unsafe) theUnsafe.get(null);

        Class cls = Class.forName("jdk.internal.module.IllegalAccessLogger");
        Field logger = cls.getDeclaredField("logger");
        u.putObjectVolatile(cls, u.staticFieldOffset(logger), null);
    } catch (Exception e) {
        // ignore
    }
}

More Related Contents:

  1. Unable to derive module descriptor for auto generated module names in Java 9?
  2. What is the replacement for javax.activation package in java 9?
  3. Why does the JVM still not support tail-call optimization?
  4. Override Java System.currentTimeMillis for testing time sensitive code
  5. How is String concatenation implemented in Java 9?
  6. Package conflicts with automatic modules in Java 9
  7. JDK9: An illegal reflective access operation has occurred. org.python.core.PySystemState
  8. Entry point for Java applications: main(), init(), or run()?
  9. JDK dateformatter parsing DayOfWeek in German locale, java8 vs java9
  10. Android Studio – No JVM Installation found
  11. Print All JVM Flags
  12. How to inject module declaration into JAR?
  13. Error occurred during initialization of boot layer FindException: Module not found
  14. Size of Huge Objects directly allocated to Old Generation
  15. Java: Which of multiple resources on classpath JVM takes?
  16. Limit jvm process memory on ubuntu
  17. Does Java JIT cheat when running JDK code?
  18. What are ReservedCodeCacheSize and InitialCodeCacheSize?
  19. Why does the JVM require warmup?
  20. Support for Compressed Strings being Dropped in HotSpot JVM?
  21. What is a stack map frame
  22. How to emit and execute Java bytecode at runtime?
  23. Classloaders hierarchy in Java 9
  24. Netty doesn’t write
  25. Attach to already running JVM
  26. Is it good to set the max and min JVM heap size the same?
  27. Which real-time (RTSJ) JVM is most preferred? [closed]
  28. Measuring time spent on GC
  29. Release java memory for OS at runtime
  30. Where do resource files go in a Gradle project that builds a Java 9 module?

Leave a Comment