使用Reflection在Abstract Class中创建一个实例 [英] Create an instance within Abstract Class using Reflection
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问题描述
是否可以使用反射
在抽象祖先类中创建派生类的实例让我们说:
Is it possible to create an instance of a derived class in abstract ancestor class using reflection Lets say:
abstract class Base {
public Base createInstance(){
//using reflection
Class<?> c = this.getClass();
Constructor<?> ctor = c.getConstructor();
return ((Base) ctor.newInstance());
}
}//end Base
class Derived extends Base {
main(){
new Derived().createInstance()
}
}
推荐答案
你可以这样做
public class Derived extends Base {
public static void main(String ... args) {
System.out.println(new Derived().createInstance());
}
}
abstract class Base {
public Base createInstance() {
//using reflection
try {
return getClass().asSubclass(Base.class).newInstance();
} catch (Exception e) {
throw new AssertionError(e);
}
}
}
打印
Derived@55fe910c
更常见的模式是使用Cloneable
A more common pattern is to use Cloneable
public class Derived extends Base {
public static void main(String ... args) throws CloneNotSupportedException {
System.out.println(new Derived().clone());
}
}
abstract class Base implements Cloneable {
@Override
public Object clone() throws CloneNotSupportedException {
return super.clone();
}
}
打印
Derived@8071a97
然而,需要应该避免使用任何一种。通常还有另一种方法可以做你需要的事情,这样基数就不会隐含地依赖于派生。
However, the need to use either should be avoided. Usually there is another way to do what you need so that base doesn't not implicitly depend on derived.
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