为什么不可能重写静态方法?
如果可能,请举例说明。
为什么不可能重写静态方法?
如果可能,请举例说明。
当前回答
现在看到上面的答案,每个人都知道我们不能重写静态方法,但不应该误解从子类访问静态方法的概念。
我们可以通过子类引用访问超类的静态方法,如果这个静态方法没有被子类中定义的新静态方法所隐藏。
例如,请参见下面的代码:-
public class StaticMethodsHiding {
public static void main(String[] args) {
SubClass.hello();
}
}
class SuperClass {
static void hello(){
System.out.println("SuperClass saying Hello");
}
}
class SubClass extends SuperClass {
// static void hello() {
// System.out.println("SubClass Hello");
// }
}
输出:
SuperClass saying Hello
关于在子类中隐藏静态方法的细节,请参阅Java oracle文档并搜索你可以在子类中做什么。
谢谢
其他回答
重写静态方法有什么好处呢?不能通过实例调用静态方法。
MyClass.static1()
MySubClass.static1() // If you overrode, you have to call it through MySubClass anyway.
编辑:似乎由于语言设计中的一个不幸疏忽,您可以通过实例调用静态方法。一般没人会这么做。我的坏。
这个问题的答案很简单,标记为静态的方法或变量只属于类,因此静态方法不能在子类中继承,因为它们只属于超类。
通过重写,可以实现动态多态。 当您说覆盖静态方法时,您试图使用的词语是矛盾的。
静态表示-编译时,重写用于动态多态性。 两者在性质上是相反的,因此不能同时使用。
动态多态行为发生在程序员使用对象并访问实例方法时。JRE将根据您使用的对象类型映射不同类的不同实例方法。
当你说覆盖静态方法时,我们将使用类名访问静态方法,它将在编译时被链接,因此没有在运行时将方法与静态方法链接的概念。因此,术语“重写”静态方法本身没有任何意义。
注意:即使你用一个对象访问一个类方法,java编译器仍然有足够的智能来发现它,并会做静态链接。
通过重写,我们可以根据对象类型创建一个多态性质。静态方法与对象无关。因此java不支持静态方法重写。
I like and double Jay's comment (https://stackoverflow.com/a/2223803/1517187). I agree that this is the bad design of Java. Many other languages support overriding static methods, as we see in previous comments. I feel Jay has also come to Java from Delphi like me. Delphi (Object Pascal) was one of the languages implementing OOP before Java and one of the first languages used for commercial application development. It is obvious that many people had experience with that language since it was in the past the only language to write commercial GUI products. And - yes, we could in Delphi override static methods. Actually, static methods in Delphi are called "class methods", while Delphi had the different concept of "Delphi static methods" which were methods with early binding. To override methods you had to use late binding, declare "virtual" directive. So it was very convenient and intuitive and I would expect this in Java.