Use of concrete class

Reports usages of concrete classes, rather than interfaces. Such declarations may represent a failure of abstraction and may make testing more difficult.

Declarations whose classes come from system or third-party libraries will not be reported by this inspection. Casts, instanceofs, and local variables are not reported in equals() method implementations. Also, casts are not reported in clone() method implementations.

Example:

interface Entity {}
class EntityImpl implements Entity {}

void processObject(Object obj) {
  // warning: instanceof of the concrete class
  if (obj instanceof EntityImpl) {
    // warning: cast to the concrete class,
    // rather than the interface
    processEntity((EntityImpl)obj);
  }
}
// warning: parameter of concrete class
void processEntity(EntityImpl obj) {
}

Use the Ignore abstract class type option to ignore casts to abstract classes.

Use the subsequent options to control contexts where the problem is reported.

Inspection options

Option	Type	Default
Ignore abstract class type	Checkbox	false
Ignore Java records	Checkbox	true
Report method return type	Checkbox	true
Report method parameter type	Checkbox	true
Report local variable type	Checkbox	true
Report static field type	Checkbox	true
Report instance field type	Checkbox	true
Report type used in instanceof, patterns, or getClass() comparison	Checkbox	true
Report type used in cast expression	Checkbox	true

Inspection Details
Available in:	IntelliJ IDEA 2023.3, Qodana for JVM 2023.3
Plugin:	Java, 233.SNAPSHOT

Last modified: 13 July 2023