Anonymous type can be replaced with method reference

Reports anonymous classes which can be replaced with method references.

Note that if an anonymous class is converted into an unbound method reference, the same method reference object can be reused by the 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.

Example:

Runnable r = new Runnable() {
  @Override
  public void run() {
    System.out.println();
  }
};

The quick-fix changes this code to the compact form: Runnable r = System.out::println;.

Use the Report when interface is not annotated with @FunctionalInterface option to enable this inspection for interfaces which are not annotated with @FunctionalInterface.

This inspection only reports if the language level of the project or module is 8 or higher.

Inspection options

Option	Type	Default
Report when interface is not annotated with @FunctionalInterface	Checkbox	true

Inspection Details
Available in:	IntelliJ IDEA 2023.3, Qodana for JVM 2023.3
Plugin:	Java, 233.SNAPSHOT

Last modified: 13 July 2023