overriding

问题 This question already has answers here : Why is method overloading and overriding needed in java? [duplicate] (3 answers) Closed 5 years ago . Recently I was asked this question "why should one override a method? " I replied, if I have a class with 10 methods and I want to use all of its functionality except one method, then I will override that method to have my own functionality. Then the interviewer replied in that case why cant we write a new method with a different name and use that

问题 I have a super class: public class SuperClass { public void dosomething() { firstMethod(); secondMethod(); } public void firstMethod() { System.out.println("Super first method"); } public void secondMethod() { System.out.println("Super second method"); } } A sub class: public class SubClass extends SuperClass { public void dosomething() { super.dosomething(); } public void firstMethod() { System.out.println("Sub first method"); } public void secondMethod() { System.out.println("Sub second

问题 This question already has an answer here : Why can't a template function resolve a pointer to a derived class to be a pointer to a base class (1 answer) Closed 5 years ago . std::string nonSpecStr = "non specialized func"; std::string const nonTemplateStr = "non template func"; class Base {}; class Derived : public Base {}; template <typename T> std::string func(T * i_obj) { ( * i_obj) += 1; return nonSpecStr; } std::string func(Base * i_obj) { return nonTemplateStr; } void run() { //

问题 Hi I have some issues in overriding a magento core block. In my module I need to override Mage_Catalog_Block_Navigation <blocks> <catalog> <rewrite> <navigation>Mycompany_Mymodule_Catalog_Block_Navigation</navigation> </rewrite> </catalog> </blocks> but this is already overridden by another magento extension from another company: <blocks> <catalog> <rewrite> <navigation>Othercompany_Othermodule_Block_Navigation</navigation> </rewrite> </catalog> </blocks> Both extension overrides different

问题 from p.46 "Effective Java" Joshua Bloch. Item 9: ALways override hashCode when you override equals Some class PhoneNumber overrides equals() and doesn't override hashCode() "two instances are involved: one is used for insertion into the HashMap, and a second, equal, instance is used for (attempted) retrieval." ... "... Even if the two instances happen to hash to the same bucket, the get method will almost certainly return null , as HashMap has an optimization that caches the hash code

问题 Imagine a simple array of structures, say: A = struct('x', {1 2 3}, 'y', {'a' 'b' 'c'}); Asking for a given property for all this array's elements will give something like: >> A.x ans = 1 ans = 2 ans = 3 Now, if I explicitly call the subsref function directly on this array, it only retrieves the first element's property: >> builtin('subsref', A, substruct('.', 'x')) ans = 1 Why? And is there a possibility to call explicitly another built-in method that will retrieve the property for all the

问题 I would like to override the .ToString() function so that whenever I get a double it outputs only 5 digits after the decimal point. How do I reffer to the object the .ToString is working on, inside the override function? In other words what shell I put instead of the XXX in the following code? public override string ToString() { if (XXX.GetType().Name == "Double") return (Math.Round(XXX, 5)); } 回答1: Why not just use the built-in formatting? var pi = 3.14159265m; Console.WriteLine(pi.ToString(

问题 I have a Class structure as follows: class Base { public: void setDefault( uint8_t my_default ) { m_default = my_default; } void method( uint8_t * subject ) { method( subject, m_default ); } virtual void method( uint8_t * subject, uint8_t parameter ) =0; protected: uint8_t m_default; }; class Derived1 : public Base { public: void method ( uint8_t * subject, uint8_t parameter ) { /* do something to subject */ } }; class Derived2 : public Base { public: void method ( uint8_t * subject, uint8_t

问题 I have th following code: class A{ //Constructor public: A(int count,...){ va_list vl; va_start(vl,count); for(int i=0;i<count;i++) /*Do Something ... */ va_end(vl); } }; class B : public A{ //Constructor should pass on args to parent public: B(int count,...) : A(int count, ????) {} }; How can I do that? Note: I would prefer to have call the constructor in the initialization list and not in the constructor body. But if this is the only way, I am also interested to hear how this works! Thanks

问题 I want to get current location using GPS. Here is my scenario. My class definition is: public class UseGps extends Activity implements LocationListener If Í try to override the LocationListener methods like this 1) @Override public void onLocationChanged(Location loc) 2) @Override public void onProviderDisabled(String provider) 3) @Override public void onProviderEnabled(String provider) it is giving me compilation error saying The method onStatusChanged(String, int, Bundle) of type UseGps