Nested class with instance main method

Reports instance main methods that are declared inside nested classes.

The invocation of main method within nested classes is not handled directly by Groovy; however, it is possible by delegating the execution to Java. In such a scenario, the code will be executed successfully only if the Java version is enough. Consider the following example:

class Outer {
  static class Nested {
    void main() {
      println 'Hello from nested'
    }
  }
}

The code runs successfully with Java 25, but not with Java 17.

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.

GroovyNestedClassWithInstanceMainMethod

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 | Groovy | Control flow issues

Inspection ID: GroovyNestedClassWithInstanceMainMethod

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 GroovyNestedClassWithInstanceMainMethod

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