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'synchronized' method

Reports the synchronized modifier on methods.

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

  1. 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.

  2. Synchronization becomes a part of a method's interface. This makes a transition to a different locking mechanism difficult.

  3. Keeping track of what is locking a particular object gets harder.

  4. 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).


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

After the quick-fix is applied:

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

You can configure the following options for this inspection:

  1. Include native methods - include native methods into the inspection's scope.

  2. Ignore methods overriding a synchronized method - do not report methods that override a synchronized method.

Inspection options

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

Include native methods

Default: Selected

Ignore methods overriding a synchronized method

Default: Selected

Inspection Details

By default bundled with:

IntelliJ IDEA 2024.1, Qodana for JVM 2024.1,

Can be installed with plugin:

Java, 241.16690

Last modified: 29 April 2024