Cast to incompatible type

Reports type cast expressions where the casted expression has a class/interface type that neither extends/implements the cast class/interface type, nor has subclasses that do.

Such a construct is likely erroneous, and will throw a java.lang.ClassCastException at runtime.

Example:

  interface A {}
  interface Z {}
  static class C {}

  void x(C c) {
    if (c instanceof Z) {
      A a = ((A)c); // cast to incompatible interface 'A'
    }
  }

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.

CastToIncompatibleInterface

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 | Probable bugs

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 CastToIncompatibleInterface

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

IntelliJ IDEA 2025.2

Inspection Details
By default bundled with:	IntelliJ IDEA 2025.2, Qodana for JVM 2025.2,

Last modified: 18 September 2025