Calling method from constructor

by

Is this expected Java behavior?

Yes.

What could cause this?

Your invocation of non-final overridden method in non-final super class constructor.

Let’s see what happens step-by-step:

  • You create an instance of B.
  • B() calls super class constructor – A(), to initialize the super class members.
  • A() now invokes a non-final method which is overridden in B class, as a part of initialization.
  • Since the instance in the context is of B class, the method load() invoked is of B class.
  • load() initializes the B class instance field – testString.
  • The super class constructor finishes job, and returns (Assuming chaining of constructor till Object class have been finished)
  • The B() constructor starts executing further, initializing it’s own member.
  • Now, as a part of initilization process, B overwrites the previous written value in testString, and re-initializes it to null.

Moral: Never call a non-final public method of a non-final class in it’s constructor.

More Related Contents:

  1. Cannot instantiate the type for class object (Java)
  2. implicit super constructor Person() is undefined. Must explicitly invoke another constructor?
  3. Java – public class constructor [duplicate]
  4. java – Explanation on “this” statement [duplicate]
  5. How to resolve an Error on a constructor? [closed]
  6. Private class property visible
  7. Implicit super constructor Event() is undefined [duplicate]
  8. Java synchronized static methods: lock on object or class
  9. How to synchronize a static variable among threads running different instances of a class in Java?
  10. what is the Class object (java.lang.Class)?
  11. Java’s Date(…) constructor is deprecated; what does that mean?
  12. What is java pojo class, java bean, normal class? [duplicate]
  13. How does Java decide when to import?
  14. Java: Static Class?
  15. Java Constructors
  16. Error: Generic Array Creation [duplicate]
  17. Does Java guarantee that Object.getClass() == Object.getClass()?
  18. Accessing constructor of an anonymous class
  19. Getting class by its name
  20. Final arguments in interface methods – what’s the point?
  21. How can I open Java .class files in a human-readable way?
  22. Instantiate a class object with constructor that accepts a string parameter?
  23. What is the maximum number of methods a Java class can have?
  24. Creating the instance of abstract class or anonymous class
  25. Test if a class contains an instance variable based on its name
  26. How do I pass a class as a parameter in Java?
  27. How can I access a private constructor of a class?
  28. How to use String.format() in Java? [duplicate]
  29. Java: Use import or explicit package / class name?
  30. In Scala, how can I subclass a Java class with multiple constructors?

Leave a Comment