Assignment to lambda parameter

Reports assignment to, or modification of lambda parameters. Although occasionally intended, this construct may be confusing and is often caused by a typo or use of a wrong variable.

The quick-fix adds a declaration of a new variable.

Example:

  list.forEach(s -> {
    s = s.trim();
    System.out.println("String: " + s);
  });

After the quick-fix is applied:

  list.forEach(s -> {
    String trimmed = s.trim();
    System.out.println("String: " + trimmed);
  });

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.

AssignmentToLambdaParameter

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 | Assignment issues

Use the Ignore if assignment is a transformation of the original parameter option to ignore assignments that modify the parameter value based on its previous value.

This inspection depends on the Java feature 'Lambda expressions', which is available since Java 8.

Inspection options

Here you can find the description of settings available for the Assignment to lambda parameter inspection, and the reference of their default values.

Ignore if assignment is a transformation of the original parameter: Default value:
Not selected

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 AssignmentToLambdaParameter

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