Why is this an issue?

The IllegalMonitorStateException is an exception that occurs when a thread tries to perform an operation on an object’s monitor that it does not own. This exception is typically thrown when a method like wait(), notify(), or notifyAll() is called outside a synchronized block or method.

IllegalMonitorStateException is specifically designed to be an unchecked exception to point out a programming mistake. This exception serves as a reminder for developers to rectify their code by correctly acquiring and releasing locks using synchronized blocks or methods. It also emphasizes the importance of calling monitor-related methods on the appropriate objects to ensure proper synchronization.

Catching and handling this exception can mask underlying synchronization issues and lead to unpredictable behavior.

Noncompliant code example

public void doSomething() {
  try {
    anObject.notify();
  } catch(IllegalMonitorStateException e) { // Noncompliant
  }
}

Compliant solution

public void doSomething() {
  synchronized(anObject) {
    anObject.notify();
  }
}

Resources