overriding

Overriding ToString() of List<MyClass>

由 喜夏-厌秋 提交于 2019-11-27 13:39:47
问题 I have a class MyClass, and I would like to override the method ToString() of instances of List: class MyClass { public string Property1 { get; set; } public int Property2 { get; set; } /* ... */ public override string ToString() { return Property1.ToString() + "-" + Property2.ToString(); } } I would like to have the following: var list = new List<MyClass> { new MyClass { Property1 = "A", Property2 = 1 }, new MyClass { Property1 = "Z", Property2 = 2 }, }; Console.WriteLine(list.ToString()); /

Overriding GetHashCode [duplicate]

由 放肆的年华 提交于 2019-11-27 13:29:31
问题 This question already has answers here : What is the best algorithm for overriding GetHashCode? (19 answers) Closed 2 years ago . As you know, GetHashCode returns a semi-unique value that can be used to identify an object instance in a collection. As a good practice, it is recommended to override this method and implement your own. My question is - do you override this method when working on custom objects? If so, what algorithm do you use to generate the unique ID? I was thinking about

Override save, put, get, etc… methods in Google App Engine

由 巧了我就是萌 提交于 2019-11-27 13:29:09
问题 Is it possible to override methids for db.Model in Google App Engine? I want to declare beforeSave, afterSave methods, etc.. to create automatic tagging system. I know there are hooks, but it seems to me a wrong way to solve this issue :) Thanks! 回答1: Yes, it's possible to override these methods. Have a look at this blog post by Nick Johnson.The hooked model class looks this: class HookedModel(db.Model): def before_put(self): pass def after_put(self): pass def put(self, **kwargs): self.before

Python Method overriding, does signature matter?

由 谁说我不能喝 提交于 2019-11-27 13:24:40
问题 Lets say I have class Super(): def method1(): pass class Sub(Super): def method1(param1, param2, param3): stuff Is this correct? Will calls to method1 always go to the sub class? My plan is to have 2 sub classes each override method1 with different params 回答1: Python will allow this, but if method1() is intended to be executed from external code then you may want to reconsider this, as it violates LSP and so won't always work properly. 回答2: In Python, methods are just key-value pairs in the

Overriding a method with different return types in java?

由 心已入冬 提交于 2019-11-27 13:14:27
I have read a book and it says I can override a method if it has the same signature. according to the book the signature of a method is Method_Name + Parameters passed. as per the book, i can override a method which has different return types. Is it actually possible to override a method with different return type in Java? because i have done a some search on the net i found people saying that to override a method the return type should be same as well. according to the book it also says the java will throw a compile error when we try to overload a method with same method name and parameters

Can't Override onPostExecute() method in AsyncTask Class or get it to trigger

由 浪子不回头ぞ 提交于 2019-11-27 12:41:17
问题 I am having trouble getting the onPostExecute() method to call when running an AsyncTask . When I try to set up my class extending AsyncTask in which the onPostExecute() is overridden I get the following build error. 'The method onPostExecute() of type AsyncTaskExampleActivity must override or implement a supertype method' I have tried getting rid of the @Override annotation. This gets rid of the build error but the method still does not execute. If any one would be so kind as to point out

Overriding a static method in python

由 泪湿孤枕 提交于 2019-11-27 12:41:00
问题 Referring to the first answer about python's bound and unbound methods here, I have a question: class Test: def method_one(self): print "Called method_one" @staticmethod def method_two(): print "Called method_two" @staticmethod def method_three(): Test.method_two() class T2(Test): @staticmethod def method_two(): print "T2" a_test = Test() a_test.method_one() a_test.method_two() a_test.method_three() b_test = T2() b_test.method_three() produces output: Called method_one Called method_two

Why is there no parameter contra-variance for overriding?

由 ◇◆丶佛笑我妖孽 提交于 2019-11-27 12:23:35
C++ and Java support return-type covariance when overriding methods. Neither, however, support contra-variance in parameter types - instead, it translates to over loading (Java) or hiding (C++). Why is that ? It seems to me that there is no harm in allowing that. I can find one reason for it in Java - since it has the "choose-the-most-specific-version" mechanism for overloading anyway - but can't think of any reason for C++. Example (Java): class A { public void f(String s) {...} } class B extends A { public void f(Object o) {...} // Why doesn't this override A.f? } On the pure issue of contra

Implementing multiple interfaces having same method

由 删除回忆录丶 提交于 2019-11-27 11:33:02
问题 This code works perfectly. The method test() works for both interfaces. What is exactly going on under the hood? And how is this feature useful in practical scenario? interface A { void test(); } interface B { void test(); } class C implements A, B { public void test() { System.out.println("abc"); } } A a = new C(); a.test(); B b = new C(); b.test(); 回答1: Because it's an interface there is no harm done. You're basically using a blueprint for your C class by implementing A and B . Both A and B

maven command line how to point to a specific settings.xml for a single command?

由 懵懂的女人 提交于 2019-11-27 10:49:45
Is it possible to point to a specific settings file in order to override the default settings.xml being used by maven for a single command? Example: mvn clean install -Dparam # -> pass specific settings file path as param to override default "home/.m2/settings.xml" You can simply use: mvn --settings YourOwnSettings.xml clean install or mvn -s YourOwnSettings.xml clean install 来源： https://stackoverflow.com/questions/25277866/maven-command-line-how-to-point-to-a-specific-settings-xml-for-a-single-command
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