TICS Coding Standard Viewer 
TIOBE Software Quality Framework
Print-friendly version
©TIOBE Software www.tiobe.com
 
TIOBE - Java Coding Standard
Search

Rule:  Design8Checked automatically with code checker

Synopsis:Don't call overridable methods during object construction
Language:Java
Severity Level:1
Category:Design


Description:
Calling overridable methods during construction poses a risk of invoking methods on an incompletely constructed object and can be difficult to discern. It may leave the sub-class unable to construct its superclass or forced to replicate the construction process completely within itself, losing the ability to call super(). If the default constructor contains a call to an overridable method, the subclass may be completely uninstantiable. Note that this includes method calls throughout the control flow graph - i.e., if a constructor Foo() calls a private method bar() that calls a public method buz(), this denotes a problem.
public class SeniorClass {
  public SeniorClass(){
      toString(); //may throw NullPointerException if overridden
  }
  public String toString(){
    return "IAmSeniorClass";
  }
}
public class JuniorClass extends SeniorClass {
  private String name;
  public JuniorClass(){
    super(); //Automatic call leads to NullPointerException
    name = "JuniorClass";
  }
  public String toString(){
    return name.toUpperCase();
  }
}