Description

Ensures that identifies classes that can be effectively declared as final are explicitly marked as final. The following are different types of classes that can be identified:

1. Private classes with no declared constructors.
2. Classes with any modifier, and contains only private constructors.

Classes are skipped if:

1. Class is Super class of some Anonymous inner class.
2. Class is extended by another class in the same file.

Examples

To configure the check:

<module name="FinalClass"/>
        

Example:

final class MyClass { // OK
  private MyClass() { }
}

class MyClass { // violation, class should be declared final
  private MyClass() { }
}

class MyClass { // OK, since it has a public constructor
  int field1;
  String field2;
  private MyClass(int value) {
    this.field1 = value;
    this.field2 = " ";
  }
  public MyClass(String value) {
    this.field2 = value;
    this.field1 = 0;
  }
}

class TestAnonymousInnerClasses { // OK, class has an anonymous inner class.
    public static final TestAnonymousInnerClasses ONE = new TestAnonymousInnerClasses() {

    };

    private TestAnonymousInnerClasses() {
    }
}

class Class1 {

    private class Class2 { // violation, class should be declared final
    }

    public class Class3 { // ok
    }

}

        

Example of Usage

• Sun Style
• Checkstyle Style

Violation Messages

• final.class

All messages can be customized if the default message doesn't suit you. Please see the documentation to learn how to.

Package

com.puppycrawl.tools.checkstyle.checks.design

Parent Module

TreeWalker