Redundant operation on empty container

Reports redundant operations on empty collections, maps or arrays.

Iterating, removing elements, sorting, and some other operations on empty collections have no effect and can be removed. Also, they may be a signal of a bug.

Example:

  if (numbers.isEmpty()){
    //error due to the missed negation
    int max = numbers.stream().max(Comparator.naturalOrder()).get();
    ...
  }

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.

RedundantOperationOnEmptyContainer

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

New in 2019.1

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 RedundantOperationOnEmptyContainer

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