overriding

Polymorphism with instance variables [duplicate]

由 邮差的信 提交于 2019-11-26 22:24:13
问题 This question already has answers here : Overriding member variables in Java ( Variable Hiding) (11 answers) Closed 6 years ago . Here are three classes that I wrote: public class Shape { public int x = 0; public void getArea() { System.out.println("I don't know my area!"); } public String toString() { return "I am a shape!"; } public int getX() { return x; } } public class Rectangle extends Shape { public int x = 1; public int getX() { return x; } public void getArea() { System.out.println(

In Python, how do I indicate I'm overriding a method?

由 不打扰是莪最后的温柔 提交于 2019-11-26 22:15:41
问题 In Java, for example, the @Override annotation not only provides compile-time checking of an override but makes for excellent self-documenting code. I'm just looking for documentation (although if it's an indicator to some checker like pylint, that's a bonus). I can add a comment or docstring somewhere, but what is the idiomatic way to indicate an override in Python? 回答1: UPDATE (23.05.2015): Based on this and fwc:s answer I created a pip installable package https://github.com/mkorpela

How to override a LESS mixin variable based on a parent's variable

由 大兔子大兔子 提交于 2019-11-26 22:11:17
问题 I am a newbie, so be gentle. I am sure my terminology is incorrect too: suppose I have my own jumbotron override: .jumbotron { background-color: #ff4400; } and then I want to have a custom override of that where I inherit the above class and only override its background color using its color as a parameter to "lighten()". I can't figure out the syntax: .Myjumbotron { .jumbotron; /* not sure what goes below for "parent.background-color" */ background-color: lighten(parent.background-color, 30%

How do Java method annotations work in conjunction with method overriding?

由 时间秒杀一切 提交于 2019-11-26 22:04:39
I have a parent class Parent and a child class Child , defined thus: class Parent { @MyAnnotation("hello") void foo() { // implementation irrelevant } } class Child { @Override foo() { // implementation irrelevant } } If I obtain a Method reference to Child::foo , will childFoo.getAnnotation(MyAnnotation.class) give me @MyAnnotation ? Or will it be null ? I'm interested more generally in how or whether annotation works with Java inheritance. trutheality Copied verbatim from http://www.eclipse.org/aspectj/doc/released/adk15notebook/annotations.html#annotation-inheritance : Annotation

Type erasure, overriding and generics

由 岁酱吖の 提交于 2019-11-26 21:59:24
Can someone explain to me why @Override public void fooMethod(Class<?> c) doesn't override public void fooMethod(Class c) and gives me the following errors instead: - Name clash: The method fooMethod(Class<?>) of type SubClass has the same erasure as fooMethod(Class) of type SuperClass but does not override it - The method fooMethod(Class<?>) of type SubClass must override a superclass method ? Edit: " java -version " says Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_16-b06-284). As for the code snippet, it's already above, pretty much; the above extends the one below. The

Override back button in android

由 瘦欲@ 提交于 2019-11-26 21:52:31
问题 I have to play a mp3 file and when click on back button on the device then automatically the song should stop. So I tried below given method. But it is not working. public void onCreate(Bundle icicle) { super.onCreate(icicle); setContentView(R.layout.audioplaying); play=(ImageView)findViewById(R.id.play); stop=(ImageView)findViewById(R.id.stop); songid=(TextView)findViewById(R.id.songid); status=(TextView)findViewById(R.id.status); String s=Songs.song; status.setText("Please Wait....!"); mp

What is the 'override' keyword in C++ used for? [duplicate]

由 泪湿孤枕 提交于 2019-11-26 21:21:15
This question already has an answer here: Is the 'override' keyword just a check for a overridden virtual method? 5 answers I am a beginner in C++. I have come across override keyword used in the header file that I am working on. May I know, what is real use of override , perhaps with an example would be easy to understand. Mats Petersson The override keyword serves two purposes: It shows the reader of the code that "this is a virtual method, that is overriding a virtual method of the base class." The compiler also knows that it's an override, so it can "check" that you are not altering/adding

Function override-overload in Java

由 前提是你 提交于 2019-11-26 20:42:35
问题 What is the difference between override and overload? 回答1: Overloading: picking a method signature at compile time based on the number and type of the arguments specified Overriding: picking a method implementation at execution time based on the actual type of the target object (as opposed to the compile-time type of the expression) For example: class Base { void foo(int x) { System.out.println("Base.foo(int)"); } void foo(double d) { System.out.println("Base.foo(double)"); } } class Child

Slight confusion regarding overriding where variables are concerned

由 六月ゝ 毕业季﹏ 提交于 2019-11-26 20:31:31
I'm preparing for the SCJP (recently rebranded as OCPJP by Oracle) and one particular question that I got wrong on a mock exam has confused me, the answer description doesn't explain things clear enough. This is the question : class A { int x = 5; } class B extends A { int x = 6; } public class CovariantTest { public A getObject() { return new A(); } public static void main(String[]args) { CovariantTest c1 = new SubCovariantTest(); System.out.println(c1.getObject().x); } } class SubCovariantTest extends CovariantTest { public B getObject() { return new B(); } } The answer is 5 , but I chose 6

Override a member function with different return type

由 南笙酒味 提交于 2019-11-26 20:25:56
问题 Consider the example below: #include <iostream> using namespace std; class base { public: virtual int func() { cout << "vfunc in base class\n"; return 0; } }; class derived: public base { public: double func() { cout << "vfunc in derived class\n"; return 0; } }; int main() { base *bptr = new derived; bptr->func(); return 0; } The compiler gives an error for the above code that there is conflicting type for the overriden function. Why is it not possible to override a function in the derived
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