super

问题 In many of Android methods, especially constructors and overridden methods, you should or even must call the parent class method using super() . When you use the Eclipse Source > Override/Implement Methods... you get code from a template with TODO tags like this: public MyCanvas(Context context, AttributeSet attrs) { super(context, attrs); // TODO Auto-generated constructor stub } @Override protected void onDraw(Canvas canvas) { // TODO Auto-generated method stub super.onDraw(canvas); } I do

问题 Is it possible to call a super static method from child static method? I mean, in a generic way, so far now I have the following: public class BaseController extends Controller { static void init() { //init stuff } } public class ChildController extends BaseController { static void init() { BaseController.loadState(); // more init stuff } } and it works, but I'd like to do it in a generic way, something like calling super.loadState(), which doesn't seem to work... 回答1: In Java, static methods

问题 Is it possible to call a super static method from child static method? I mean, in a generic way, so far now I have the following: public class BaseController extends Controller { static void init() { //init stuff } } public class ChildController extends BaseController { static void init() { BaseController.loadState(); // more init stuff } } and it works, but I'd like to do it in a generic way, something like calling super.loadState(), which doesn't seem to work... 回答1: In Java, static methods

问题 I wonder when to use what flavour of Python 3 super(). Help on class super in module builtins: class super(object) | super() -> same as super(__class__, <first argument>) | super(type) -> unbound super object | super(type, obj) -> bound super object; requires isinstance(obj, type) | super(type, type2) -> bound super object; requires issubclass(type2, type) Until now I've used super() only without arguments and it worked as expected (by a Java developer). Questions: What does "bound" mean in

问题 I'd like to override a method in an Objective C class that I don't have the source to. I've looked into it, and it appears that Categories should allow me to do this, but I'd like to use the result of the old method in my new method, using super to get the old methods result. Whenever I try this though, my method gets called, but "super" is nil... Any idea why? I'm doing iPhone development with the XCode 2.2 SDK. I'm definitely working with an instance of a class, and the method of the class

问题 In Python, how do I pick which Parent's method to call? Say I want to call the parent ASDF2's __init__ method. Seems like I have to specify ASDF1 in the super()..? And if I want to call ASDF3's __init__ , then I must specify ASDF2 ?! >>> class ASDF(ASDF1, ASDF2, ASDF3): def __init__(self): super(ASDF1, self).__init__() >>> ASDF() ASDF2's __init__ happened >>> class ASDF(ASDF1, ASDF2, ASDF3): def __init__(self): super(ASDF2, self).__init__() >>> ASDF() ASDF3's __init__ happened Seems bonkers

问题 In Python, how do I pick which Parent's method to call? Say I want to call the parent ASDF2's __init__ method. Seems like I have to specify ASDF1 in the super()..? And if I want to call ASDF3's __init__ , then I must specify ASDF2 ?! >>> class ASDF(ASDF1, ASDF2, ASDF3): def __init__(self): super(ASDF1, self).__init__() >>> ASDF() ASDF2's __init__ happened >>> class ASDF(ASDF1, ASDF2, ASDF3): def __init__(self): super(ASDF2, self).__init__() >>> ASDF() ASDF3's __init__ happened Seems bonkers

问题 Why can I use super only with wildcards and not with type parameters? For example, in the Collection interface, why is the toArray method not written like this interface Collection<T>{ <S super T> S[] toArray(S[] a); } 回答1: super to bound a named type parameter (e.g. <S super T> ) as opposed to a wildcard (e.g. <? super T> ) is ILLEGAL simply because even if it's allowed, it wouldn't do what you'd hoped it would do, because since Object is the ultimate super of all reference types, and

问题 I am trying to read a list of exercises from a file Exercises.txt in my /assests folder and I've found plenty of examples how to, but I keep getting the error "context cannot be resolved" and if I manage to fix that, then I get "Default constructor cannot handle exception type IOException thrown by implicit super constructor. Must define an explicit constructor" Here is my code: class ChooseExercises extends ListActivity{ String[] exercises; AssetManager am = context.getAssets(); //Error 1

问题 Please help me find errors from this code. I'm still new and I don't know if this is correct or not. I do have one error. This is the error: constructor Person in class Person cannot be applied to given types; super(); ^ required: String,String,String found: no arguments reason: actual and formal argument lists differ in length This is my code: import java.util.*; public class Person { //Data fields private String lastName; private String middleInitial; private String firstName; /