superclass

问题 I've got a method that accepts a parameter of type Class , and I want to only accept classes that extend SuperClass . Right now, all I can figure out to do is this, which does a run-time check on an instance: public function careless(SomeClass:Class):void { var instance:SomeClass = new SomeClass(); if (instance as SuperClass) { // great, i guess } else { // damn, wish i'd have known this at compile time } } Is there any way to do something like this, so I can be assured that a Class instance

问题 I've got a method that accepts a parameter of type Class , and I want to only accept classes that extend SuperClass . Right now, all I can figure out to do is this, which does a run-time check on an instance: public function careless(SomeClass:Class):void { var instance:SomeClass = new SomeClass(); if (instance as SuperClass) { // great, i guess } else { // damn, wish i'd have known this at compile time } } Is there any way to do something like this, so I can be assured that a Class instance

问题 I want to make a Name Entity Recognizer using wikipedia Data, I need to get all the super classes of a word to see in which category (Place, Human, Organization or None) the word is. I surfed the Internet a lot and find some pages like : SPARQL query to find all sub classes and a super class of a given class which when I execute the query results "No matching records found" even with the word mentioned in the page and trying other namespaces. and: Extracting hierarchy for dbpedia entity using

问题 I have a method set in my superclass... public void explain() { for (Item item: Instances) { System.out.println(item.getname + " is in location " + item.place): } } I need to override this same method in the subclass to print out the original output message but the new instance for this method needs to print out different values that have been set in the subclass I'm confused with the overriding bit (as I know little about it) and would like an explanation. 回答1: So just give the method in

问题 I've looked around here find an answer to my question and I can't. How do you call a subclass method from a superclass in Java? Basically what I'm looking to do is this: I have a method called exec that takes a String as a parameter for a command. I want to be able to call the exec method in the subclass that the developer has overridden from the superclass without knowing the subclasses name ahead of time. This is like the way the Thread class works. I'm not looking to do what every answer I

问题 I've looked around here find an answer to my question and I can't. How do you call a subclass method from a superclass in Java? Basically what I'm looking to do is this: I have a method called exec that takes a String as a parameter for a command. I want to be able to call the exec method in the subclass that the developer has overridden from the superclass without knowing the subclasses name ahead of time. This is like the way the Thread class works. I'm not looking to do what every answer I

问题 Please explain public class Contact { private String contactId; private String firstName; private String lastName; private String email; private String phoneNumber; public Contact(String contactId,String firstName, String lastName, String email, String phoneNumber) { super(); //what does standalone super() define? With no args here? this.firstName = firstName; this.lastName = lastName; //when is this used?, when more than one args to be entered? this.email = email; this.phoneNumber =

问题 In the Chapter 7.3.5 "Inheritance and Instance Variables" of the book "the ruby programing language" says : Because instance variables have nothing to do with inheritance, it follows that an instance variable used by a subclass cannot “shadow” an instance variable in the superclass. If a subclass uses an instance variable with the same name as a variable used by one of its ancestors, it will overwrite the value of its >ancestor’s variable. This can be done intentionally, to alter the behavior

问题 Watch the following example: class A { public: A(int param1, int param2, int param3) { // ... } }; class B : public A { public: B() : m_param1(1), m_param(2), m_param(3), A(m_param1, m_param2, m_param3) { // ... } }; B b; Obviously, when "b" will be created, A's ctor will be called before the parameters of B will be initialized. This rule prevents me from creating "wrapper" classes which simplify the class's initialization. What is the "right way" for doing it? Thanks, Amir PS: In my

问题 i have 2 classes, called superclass and subclass, i tried to cast the subclass object to superclass, but its seems does not work when i want to use the subclass object from the superclass. Please help to explain. Thanks. These are the code:- public class superclass { public void displaySuper() } System.out.println("Display Superclass"); } } public class subclass extends superclass { public void displaySub() { System.out.println("Display Subclass"); } } public class Testing { public static