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I have seen some code as follows
public interface IBean {
}
and its usage at some places as
public void persist(List<? extends IBean> beansList) {
}
However same can achieved with following code
public void persist(List<IBean> beansList) {
}
So what is the difference between both methods, both are excepting objects that must inherit IBean interface?
Here are the bean classes
public class Category implement IBean {
//related fields
}
public class Product implement IBean {
//related fields
}
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The following table explains the difference between the extends and interface: 1. 2. It is not compulsory that subclass that extends a superclass override all the methods in a superclass. It is compulsory that class implementing an interface has to implement all the methods of that interface. 3. Only one superclass can be extended by a class. 4.
Here, the ProgrammingLanguage class implements the interface and provides the implementation for the method. In Java, a class can also implement multiple interfaces. For example, Similar to classes, interfaces can extend other interfaces. The extends keyword is used for extending interfaces.
The interface includes an abstract method getName (). Here, the ProgrammingLanguage class implements the interface and provides the implementation for the method. In Java, a class can also implement multiple interfaces. For example, Similar to classes, interfaces can extend other interfaces.
We can extend a class but we cannot implement a class. We can implement an interface, but cannot extend an interface. In what cases should we be using extends? Show activity on this post. class ClassX extends ClassY { ... } interface InterfaceA extends InterfaceB { ... }
You can pass a List<Category> to public void persist(List<? extends IBean> beansList), but you cannot pass a List<Category> to public void persist(List<IBean> beansList).
On the other hand, you can pass a List<IBean> to both methods.
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