Anonymous2MethodRef

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();
    }
  };

After the quick-fix is applied:

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.