Double brace initialization

Reports Double Brace Initialization.

Compared to regular initialization, double brace initialization provides worse performance since it requires loading an additional class.

It may also cause failure of equals() comparisons if the equals() method doesn't accept subclasses as parameters.

Double brace initialization may cause memory leaks when used in a non-static context. This is because it defines an anonymous class that will reference the surrounding object, when compiled with javac from before Java 18.

In addition, before Java 9, double brace initialization couldn't be combined with the diamond operator since it was incompatible with anonymous classes.

Example:

  List<Integer> list = new ArrayList<>() {{
    add(1);
    add(2);
  }};

After the quick-fix is applied:

  List<Integer> list = new ArrayList<>();
  list.add(1);
  list.add(2);

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.

DoubleBraceInitialization

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 | Initialization

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 DoubleBraceInitialization

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

IntelliJ IDEA 2025.2

Inspection Details
By default bundled with:	IntelliJ IDEA 2025.2, Qodana for JVM 2025.2,

Last modified: 18 September 2025