Collection added to itself

Reports cases where the argument of a method call on a java.util.Collection or java.util.Map is the collection or map itself. Such situations may occur as a result of copy-paste in code with raw types.

Example:

  ArrayList list = new ArrayList<>();
  list.add(list); // warning here
  return list.hashCode(); // throws StackOverflowError

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.

CollectionAddedToSelf

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 | Probable bugs

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 CollectionAddedToSelf

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