extends

问题 In java when an interface extends another interface: Why does it implement its methods? How can it implement its methods when an interface can't contain a method body How can it implement the methods when it extends the other interface and not implement it? What is the purpose of an interface implementing another interface? This has major concepts in Java! EDIT: public interface FiresDragEvents { void addDragHandler(DragHandler handler); void removeDragHandler(DragHandler handler); } public

问题 Below is the db connection class I came out with so far, but I am going to improve it by extending the PDO class itself, <?php class database { protected $connection = null; #make a connection public function __construct($hostname,$dbname,$username,$password) { try { # MySQL with PDO_MYSQL $this->connection = new PDO("mysql:host=$hostname;dbname=$dbname", $username, $password); $this->connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); } catch (PDOException $e) { $this-

问题 In my TypeScript project, I use DefinitelyTyped definitions for external js dependencies. Sometimes it might happen that these definitions are outdated. It might also happen than some libraries can add new methods at runtime, like express-validator in which you can define custom validator functions. Therefore I would like to extend those .d.ts definitions adding new methods and/or properties. So if I have my DefinitelyTyped defininiton in express-validator.d.ts : declare module

问题 I am extending change_list.html and I need to output a variable defined in settings.py. How do I pass that particular variable into the custom admin template context? 回答1: class MyModelAdmin(admin.ModelAdmin): ... def changelist_view(self, request, extra_context=None): extra_context = extra_context or {} extra_context['some_var'] = 'This is what I want to show' return super(MyModelAdmin, self).changelist_view(request, extra_context=extra_context) See: https://docs.djangoproject.com/en/dev/ref

问题 I wondering how to correctly infer 2th and 3th template of my function suppose a simple interface interface ISome { a: string; b?: { c: string; }; } follow works function pathBuilder< K1 extends keyof ISome, K2 extends keyof NonNullable<ISome[K1]>>(p: K1, p2?: K2) { let res = String(p); if (p2) { res += "." + p2; } return res; } const pathTest = pathBuilder("b", "c"); // ---> "b.c" and intellisense works on parameters but I need to generalize the function to work by specify another type ( I

问题 I've got a problem with this class. This Activity will be called when I press a button. When I extend Activity to this class the programm gets into the class, but when I extend ListActiviy and I click the button the debugger tells me in red words "source not found" and nothing else, not even something in the logcat. Please tell me if there is something missing in the xml-file of this activity or the manifest. This is the class activity: public class SeeAllEntriesActivity extends ListActivity

问题 Since using PHP 7.0 and higher, the strict mode of php generates warnings like this: PHP Warning: Declaration of In2code\Femanagerextended\Controller\EditController::updateAction(In2code\Femanagerextended\Domain\Model\User $user) should be compatible with In2code\Femanager\Controller\EditController::updateAction(In2code\Femanager\Domain\Model\User $user) in ($PATH)\typo3conf\ext\femanagerextended\Classes\Controller\EditController.php line 17 when trying to extend an existing controller of the

问题 I've got a Validator class and a UserValidator class which extends from it. My Validator has a public method setRule(...) with public visibility. When I extend from it I want to change the visibility of the setRule(...) parent method to private/protected within the child so that it's only visible for the child and no outsiders can call this method from the child. Is that possible? If so, how could I achieve it? 回答1: From an architectural point of view this is not recommended. As already

问题 I have a custom class which I am extending for various purposes, and the following code is working just fine: class Inator { constructor(whichCanvas) { this.myCanvas = whichCanvas; } } class Ballgowninator extends Inator { constructor(whichCanvas) { super(whichCanvas); this.myCanvas.addEventListener("mousedown",this.handleMouseDown); this.myCanvas.addEventListener("mouseup",this.handleMouseUp); } handleMouseDown(e) { alert("ballgowninator mousedown"); } handleMouseUp(e) { alert(

问题 I have an class as below: public class FYPSmsReceiverBroadcast extends BroadcastReceiver I need to unregister the receiver as I am getting a force close error AFTER I have existed the application when I receive an SMS message. (indicating something is still listening for the sms but not able to access a particular activity because the app has been closed; the error only seems to happen after 1 text received, a second text seems to produce no force close error) There are a number of somewhat