superclass

This code throws an exception, AttributeError, "wtf!" , because A.foo() is calling B.foo1() , shouldn't it call A.foo1() ? How can I force it to call A.foo1() (and any method call inside A.foo() should call A.* ) class A(object): def foo(self): print self.foo1() def foo1(self): return "foo" class B(A): def foo1(self): raise AttributeError, "wtf!" def foo(self): raise AttributeError, "wtf!" def foo2(self): super(B, self).foo() myB = B() myB.foo2() In class A instead of calling self methods you need to call A methods and pass in self manually. This is not the normal way of doing things -- you

I am working on a project and i am getting the error "implicit super constructor Person() is undefined. Must explicitly invoke another constructor" and i don't quite understand it. Here is my person class: public class Person { public Person(String name, double DOB){ } } And my student class when trying to implement the person class, and giving it an instructor variable. public class Student extends Person { public Student(String Instructor) { } } If a constructor does not explicitly invoke a superclass constructor, the Java compiler automatically inserts a call to the no-argument constructor

I have a package with JAXB annotated classes with an abstract superclass. I want to use this superclass in web service interface, so I can pass any of subclasses as a parameter. When I do it, an exception is thrown: javax.xml.ws.WebServiceException: javax.xml.bind.UnmarshalException - with linked exception: [javax.xml.bind.UnmarshalException: Unable to create an instance of xxx.yyy.ZZZ - with linked exception: [java.lang.InstantiationException]] It is possible to manually marshall/unmarshall & pass parameter as a string, but I would like to avoid it. Any ideas how to do it? Have you specified

All the ExtJS documentation and examples I have read suggest calling superclass methods like this: MyApp.MyPanel = Ext.extend(Ext.Panel, { initComponent: function() { // do something MyPanel specific here... MyApp.MyPanel.superclass.initComponent.call(this); } }); I have been using this pattern for quite some time and the main problem is, that when you rename your class then you also have to change all the calls to superclass methods. That's quite inconvenient, often I will forget and then I have to track down strange errors. But reading the source of Ext.extend() I discovered, that instead I

In the following code- class Mammal { String name = "furry "; String makeNoise() { return "generic noise"; } } class Zebra extends Mammal { String name = "stripes "; String makeNoise() { return "bray"; } } public class ZooKeeper { public static void main(String[] args) { new ZooKeeper().go(); } void go() { Mammal m = new Zebra(); System.out.println(m.name + m.makeNoise()); Zebra z = new Zebra(); System.out.println(z.name + z.makeNoise()); } } Both objects ( m and z ), if I see in debug windows of eclipse, contain both values of name variable ( furry and stripes ). I do understand that in

Okay, so, for example, let's say I have an abstract class called "Vehicle". The Vehicle class, has, among other things, a static variable called wheels, which is not initialized. What I want to do is have other subclasses extending from the Vehicle class, like "Motorcycle", and "Truck", and in these subclasses, have the wheels initialized. Code: public abstract class Vehicle { static int wheels; //number of wheels on the vehicle } But the below doesn't work: public class Motorcycle extends Vehicle { wheels = 2; } Is there a way to do this effectively? EDIT: Thank you to all the people who