Iteration over 'keySet()' can be optimized

Reports iterations over the keySet() of a java.util.Map instance, where the iterated keys are used to retrieve the values from the map.

Such iteration may be more efficient when replaced with an iteration over the entrySet() or values() (if the key is not actually used).

Similarly, keySet().forEach(key -> ...) can be replaced with forEach((key, value) -> ...) if values are retrieved inside a lambda.

Example:

  for (Object key : map.keySet()) {
   Object val = map.get(key);
  }

After the quick-fix is applied:

for (Object val : map.values()) {}

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.

KeySetIterationMayUseEntrySet

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 | Performance

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 KeySetIterationMayUseEntrySet

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