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();
    }
  };

After the quick-fix is applied:

Runnable r = System.out::println;

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.

Anonymous2MethodRef

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.

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 depends on the Java feature 'Method references' which is available since Java 8.

Inspection options

Here you can find the description of settings available for the Anonymous type can be replaced with method reference inspection, and the reference of their default values.

Report when interface is not annotated with @FunctionalInterface: Default: Selected

Availability

By default bundled with: IntelliJ IDEA 2024.1, Qodana for JVM 2024.1,
Can be installed with plugin: Java, 241.18072

Last modified: 18 June 2024