Mapping call before count()

Reports redundant Stream API calls like map(), or boxed() right before the count() call.

Such calls don't change the final count, so could be removed. It's possible that the code relies on a side effect from the lambda inside such a mapping call. However, relying on side effects inside the stream chain is extremely bad practice. There are no guarantees that the call will not be optimized out in future Java versions.

Example:

  // map() call is redundant
  long count = list.stream().filter(s -> !s.isEmpty()).map(s -> s.trim()).count();

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.

MappingBeforeCount

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 | Verbose or redundant code constructs

This inspection depends on the Java feature 'Stream and Optional API', which is available since Java 8.

New in 2024.1

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 MappingBeforeCount

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