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2024.3

Anonymous type can be replaced with lambda

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Last modified: 03 December 2024

Reports anonymous classes which can be replaced with lambda expressions.

Example:

After the quick-fix is applied:

Note that if an anonymous class is converted into a stateless lambda, the same lambda object can be reused by Java runtime during subsequent invocations. On the other hand, when an anonymous class is used, separate objects are created every time. Thus, applying the quick-fix can cause the semantics change in rare cases, e.g. when anonymous class instances are used as HashMap keys.

Use the Report when interface is not annotated with @FunctionalInterface option to ignore the cases in which an anonymous class implements an interface without @FunctionalInterface annotation.

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