Double-checked locking

Reports double-checked locking.

Double-checked locking tries to initialize a field on demand and in a thread-safe manner, while avoiding the cost of synchronization. Unfortunately it is not thread-safe when used on a field that is not declared volatile. When using Java 1.4 or earlier, double-checked locking doesn't work even with a volatile field. Read the article linked above for a detailed explanation of the problem.

Example of incorrect double-checked locking:

  class Foo {
    private Helper helper = null;
    public Helper getHelper() {
      if (helper == null)
        synchronized(this) {
          if (helper == null) helper = new Helper();
        }
        return helper;
      }
    }
    // other functions and members...
  }

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.

DoubleCheckedLocking

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

Inspection ID: DoubleCheckedLocking

Suppressing Inspection

You can suppress this inspection by placing the following comment marker before the code fragment where you no longer want messages from this inspection to appear:

//noinspection DoubleCheckedLocking

More detailed instructions as well as other ways and options that you have can be found in the product documentation:

IntelliJ IDEA 2025.3

Inspection Details
By default bundled with:	IntelliJ IDEA 2025.3, Qodana for JVM 2025.3,

Last modified: 03 December 2025