subclass

I know that a class can implement more than one interface, but is it possible to extend more than one class? For example I want my class to extend both TransformGroup and a class I created. Is this possible in Java? Both statements class X extends TransformGroup extends Y and class X extends TransformGroup, Y receive an error. And if it is not possible, why? TransformGroup extends Group but I guess it also extends Node since it inherits fields from Node and it can be passed where a Node object is required. Also, like all classes in Java, they extend Object class. So why wouldn't it be possible

please note that I am trying to use NotifyCollectionChangedAction.Add action instead of .Reset. the latter does work, but it is not very efficient with large collections. so i subclassed ObservableCollection: public class SuspendableObservableCollection<T> : ObservableCollection<T> for some reason, this code: private List<T> _cachedItems; ... public void FlushCache() { if (_cachedItems.Count > 0) { foreach (var item in _cachedItems) Items.Add(item); OnCollectionChanged(new NotifyCollectionChangedEventArgs( NotifyCollectionChangedAction.Add, (IList<T>)_cachedItems)); } } is throwing A

How is it possible to have an instance of a class which is an object , without the class being a subclass of object ? here is an example: >>> class OldStyle(): pass >>> issubclass(OldStyle, object) False >>> old_style = OldStyle() >>> isinstance(old_style, object) True hamstergene In Python 2, type and class are not the same thing, specifically, for old-style classes, type(obj) is not the same object as obj.__class__ . So it is possible because instances of old-style classes are actually of a different type ( instance ) than their class: >>> class A(): pass >>> class B(A): pass >>> b = B() >>>

I have an NSMutableArray object that I want to add custom methods to. I tried subclassing NSMutableArray but then I get an error saying "method only defined for abstract class" when trying to get the number of objects with the count method. Why is the count method not inherited? I read somewhere else that I will have to import some NSMutableArray methods into my custom class if I want to use them. I just want to add a custom method to the NSMutableArray class. So should I subclass NSMutableArray, or should I do something else? PeyloW NSMutableArray is not a concrete class, it is just the

I'm writing a custom view that directly extends android.view.View . If I try to access fields mScrollX or mScrollY , I see an error that the field "cannot be resolved or is not a field." The source code for android.view.View has mScrollX, mScrollY, and similar variables declared protected . How is it that my direct subclass cannot access protected fields of its parent class? (Classes like ScrollView apparently can.) P.S. I realize that I can call getScrollX() , but I want to update these fields; calling setScroll() has side effects that I don't want. It's because they are not part of the

I was told that for a Java subclass it can inherit all members of its superclass. So does this mean even private members? I know it can inherit protected members. Can someone explain this to me. I am now totally confused. sgokhales No, the private member are not inherited because the scope of a private member is only limited to the class in which it is defined. Only the public and protected member are inherited. From the Java Documentation , Private Members in a Superclass A subclass does not inherit the private members of its parent class. However, if the superclass has public or protected

According to some official talk, a class in Objective-C should only expose public methods and properties in its header: @interface MyClass : NSObject @property (nonatomic, strong) MyPublicObject *publicObject; - (void)publicMethod; @end and private methods/properties should be kept in class extension in .m file: @interface MyClass() @property (nonatomic, strong) MyPrivateObject *privateObject; - (void) privateMethod; @end and I don't think there is a protected type for things that are private but accessible from subclasses. I wonder, is there anyway to achieve this, apart from declaring