abstract

问题 I have a made an engine class that is as follows. based on Engine: Interface that extends Java’s Comparable (to compare among engines) and declares an integer getter method “getForce”, which indicatesthat engine subclasses will have a force they are capable of producing. public interface Engine extends Comparable<Engine>{ public int getForce(); } I am trying to make an AbstractEngine class based on the following description. AbstractEngine : Abstract class implemented by most engines. It

问题 I'm wondering how the following code is optimized. Specifically concerning virtual and direct calls. I have commented on how I think everything is optimized but those are just guesses. public abstract class Super { public abstract void Foo(); public void FooUser() { Foo(); } } public class Child1 : Super { public override void Foo() { //doSomething } } public class SealedChild : Super { public override void Foo() { //doSomething } } class Program { void main() { Child1 child1 = new Child1();

问题 One can use the STL binary search algorithms (binary_search, upper_bound, lower_bound) to search a vector of Base pointers for a derived object, as shown below. Since Base is abstract (protected constructor), one has to instantiate a Derived object for the search functions, which is slightly ugly. I want to search the vector for the first Derived above a given time. Can I do this without arbitrarily picking and instantiating one of my many inherited classes? #include <algorithm> #include

问题 I have problem with this code: @SuppressWarnings("deprecation") @TargetApi(Build.VERSION_CODES.KITKAT) public class NotificationRemoteControllerService extends NotificationService implements OnClientUpdateListenerExtended { private static final String TAG = "NRemoteContollerService"; public static boolean isMusicPlaying = false; MusicPlaybackState currenTplaybackState; // REMOTE CONTROLLER private int currentPlaybackState; private SimpleMusicMetadata simpleMusicMetadata; private

问题 I would like to test a method from an abstract class. In this class is there a abstract method with is static. I use PHPUnit. With normal abstract methods it works: <?php abstract class AbstractClass { public function concreteMethod() { return $this->abstractMethod(); } public abstract function abstractMethod(); } class AbstractClassTest extends PHPUnit_Framework_TestCase { public function testConcreteMethod() { $stub = $this->getMockForAbstractClass('AbstractClass'); $stub->expects($this-

问题 I'm wondering is is it possible to pass on abstract class's property (or function) values a instance class argument? Or do I have to create a private member variable, assign data to it and pass this one to the instance class argument instead? That's sounds confusing, so the example below will help to clarify it better. Take a look at the "new DealerAccountRepository(MyEnvironmentSetting);" section in the "DatabaseDataDealer" class. public abstract class AEnvironmentSetting { //Constructor...

问题 I was trying out the below python code: from abc import ABCMeta, abstractmethod class Bar: __metaclass__ = ABCMeta @abstractmethod def foo(self): pass class Bar2(Bar): def foo2(self): print("Foo2") b = Bar() b2 = Bar2() I thought having @abstractmethod will ensure that my parent class will be abstract and the child class would also be abstract as it is not implementing the abstract method. But here, I get no error trying to instantiate both the classes. Can anyone explain why? 回答1: You must

问题 I am using the EclipseLink implementation (2.3) of JAXB to map POJOs to XML and encountering a problem with following usecase: public abstract class A { public abstract Set<X> getX(); // There is no setter } public class B extends A { // Set via constructor private Set<X> x; @Override public Set<X> getX(); } I am defining the mapping itself completely in an external bindings-file, i set class A to be transient like so: <java-type name="foo.A" xml-transient="true"/> and for class B: <java-type

问题 Going over The SplSubject interface on the php manual site and noticed. SplSubject { /* Methods */ abstract public void attach ( SplObserver $observer ) abstract public void detach ( SplObserver $observer ) abstract public void notify ( void ) } I can't figure out what the key word "abstract" does in the code or why it is there. Also never seen/used a function return type in php (Such as void)? Thank you 回答1: The interface declaration you've seen there is pseudo code . Meaning it is not meant

问题 I created abstract class for my ArrayList holders public abstract class ArrayHolder { Gson g = new Gson(); } used like public class MyHolder extends ArrayHolder { ArrayList<MyType> myList = new ArrayList<MyType>(); } I would like to create abstract function to fill this ArrayList from String and Type argument like this ( String data is JSON in String ) : This function should be rewritten public ArrayList<T> arrayType(String data, T type){ return g.fromJson(data, new TypeToken<ArrayList<type>(