'instanceof' check for 'this'

Reports usages of instanceof or getClass() == SomeClass.class in which a this expression is checked.

Such expressions indicate a failure of the object-oriented design, and should be replaced by polymorphic constructions.

Example:

class Super {
  void process() {
    if (this instanceof Sub) { // warning
      doSomething();
    } else {
      doSomethingElse();
    }
  }
}
  
class Sub extends Super {}

To fix the problem, use an overriding method:

class Super {
  void process() {
    doSomethingElse();
  }
}
  
class Sub extends Super {
  @Override
  void process() {
    doSomething();
  }
}  

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.

InstanceofThis

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.

Settings or Preferences | Editor | Inspections | Java | Abstraction issues

Inspection ID: InstanceofThis

Suppressing Inspection

You can suppress this inspection by placing the following comment marker before the code fragment where you no longer want messages from this inspection to appear:

//noinspection InstanceofThis

More detailed instructions as well as other ways and options that you have can be found in the product documentation:

IntelliJ IDEA 2025.3

Inspection Details
By default bundled with:	IntelliJ IDEA 2025.3, Qodana for JVM 2025.3,

Last modified: 03 December 2025