Overcoming the Java 9 Illegal Reflective Access Warning and Writing Error-Free Code

Java 9 Illegal Reflective Access Warning

Java 9 introduced a new warning message that appears in the console when there is an illegal reflective access operation. What does this warning mean and why is it being shown?

The warning message “Warning: Illegal reflective access by xxx to field yyy” indicates that an application or library is attempting to access a restricted field in a class or interface. This is an illegal operation according to Java's strict security rules and should be avoided, since it can open up security risks. The warning is meant to alert developers to potentially dangerous code and should be taken seriously.

When a code attempts to access a restricted field, the public or protected modifiers on the field are ignored and the access is refused by the JVM. This prevents malicious code from using reflective access to gain access to sensitive information or other restricted components. As such, it is strongly recommended that developers not attempt to use any form of reflective access to gain access to restricted fields.

If you receive this warning when running your code, it means that something in your application is trying to use reflective access to access a restricted field. You should investigate the code to determine what it is trying to do and make sure that it isn’t attempting to do anything malicious. Additionally, you should try to modify the code to remove the reflective access in order to keep your application secure.

The Illegal Reflective Access Warning is an important message to be aware of when running Java 9 applications. All developers must take this warning seriously and investigate their code in order to ensure that they aren’t introducing any unforeseen security risks into their applications.