TIOBE - Java Coding Standard

Rule: Design22

Synopsis:	Declare private fields final, if possible
Language:	Java
Severity Level:	3
Category:	Design

Description:

Identifies private fields whose values never change once they are initialized either in the declaration of the field or by a constructor. This aids in converting existing classes to immutable classes.

public class Foo {
  private int x; // could be final
  public Foo() {
      x = 7;
  }
  public void foo() {
     int a = x + 2;
  }
}