Cleaner captures object reference

Reports Runnable passed to a Cleaner.register() capturing reference being registered. If the reference is captured, it will never be phantom reachable and the cleaning action will never be invoked.

Possible sources of this problem:

Lambda using non-static methods, fields, or this itself
Non-static inner class (anonymous or not) always captures this reference in java up to 18 version
Instance method reference
Access to outer class non-static members from non-static inner class

Locating this inspection

By ID

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CapturingCleaner

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Settings or Preferences | Editor | Inspections | Java | Probable bugs

Sample of code that will be reported:

  int fileDescriptor;
  Cleaner.Cleanable cleanable = Cleaner.create().register(this, () -> {
    System.out.println("adsad");
    //this is captured via fileDescriptor
    fileDescriptor = 0;
  });

This inspection only reports if the language level of the project or module is 9 or higher.

New in 2018.1

Inspection Details
By default bundled with:	IntelliJ IDEA 2024.2, Qodana for JVM 2024.2,
Can be installed with plugin:	Java, 242.22892

Last modified: 11 September 2024