'synchronized' method

Reports the synchronized modifier on methods.

There are several reasons a synchronized modifier on a method may be a bad idea:

As little work as possible should be performed under a lock. Therefore it is often better to use a synchronized block and keep there only the code that works with shared state.
Synchronization becomes a part of a method's interface. This makes a transition to a different locking mechanism difficult.
Keeping track of what is locking a particular object gets harder.
The DoS (denial-of-service) attack becomes feasible either on purpose or unknowingly when inheriting the method's class.

As an alternative, consider synchronizing on a private final lock object, access to which can be completely controlled.

A quick-fix is provided to wrap the method body with synchronized(this).

Example:

  class Main {
    public synchronized void fooBar() {
    }
  }

After the quick-fix is applied:

  class Main {
    public void fooBar() {
      synchronized (this) {
      }
    }
  }

Locating this inspection

By ID

Can be used to locate inspection in e.g. Qodana configuration files, where you can quickly enable or disable it, or adjust its settings.

SynchronizedMethod

Via Settings dialog

Path to the inspection settings via IntelliJ Platform IDE Settings dialog, when you need to adjust inspection settings directly from your IDE.

Settings or Preferences | Editor | Inspections | Java | Threading issues

You can configure the following options for this inspection:

Include native methods - include native methods into the inspection's scope.
Ignore methods overriding a synchronized method - do not report methods that override a synchronized method.

Here you can find the description of settings available for the 'synchronized' method inspection, and the reference of their default values.

Last modified: 18 June 2024