![]() ![]() I've raised this question on the OpenJDK compiler-dev mailing list. But perhaps this went too far and accidentally did full initialization instead. One might think this is part of the class/interface preparation stage ( JLS 12.3.2) which initializes things like method tables. Prior to Java 8 and default methods, invokevirtual could never end up executing code in an interface, so this didn't arise. My speculation is that the HotSpot implementation wanted to avoid adding class/interface initialization checking into the critical path of the invokevirtual call. ![]() The default method doesn't have to be called or overridden or even mentioned, nor does the presence of an abstract method trigger initialization. Which clearly indicates that interface I is being initialized where it wasn't before! The mere presence of the default method is enough to trigger the initialization. public class Example // causes initialization! Initialized before the interface is initialized.įor my own curiosity, I tried it and, as expected, the interface InterfaceType was not initialized. Similarly, the superinterfaces of an interface are not Initialized, but interfaces implemented by the class are not We must override the default methods explicitly with its interface name.While searching through the Java Language Specification to answer this question, I learned thatīefore a class is initialized, its direct superclass must be It allows us to implement these two interfaces, from a class. The advantage of interfaces is that it can have the same default methods with the same name and signature in two different interfaces. Because they are already implementing these interfaces. The only difference is that it is defined inside the interfaces with the default implementation. The default method is similar to the abstract method. We can achieve multiple inheritance by using these two things. The solution to the diamond problem is default methods and interfaces. It is sometimes referred to as the deadly diamond of death. It is a serious problem for other OPPs languages. It is an ambiguity that can rise as a consequence of allowing multiple inheritance. In the above figure, we find that class D is trying to inherit form class B and class C, that is not allowed in Java. What Java does not allow is multiple inheritance where one class can inherit properties from more than one class. For example, class C can inherit its property from B class which itself inherits from A class. ![]() Multi-level inheritance allows a child class to inherit properties from a class that can inherit properties from some other classes. for example, if class B inherits properties from only one super-class A, then it is called simple inheritance, and Java supports them. But remember that Java does not support the multiple inheritance because of the diamond problem.Īs simple inheritance allows a child class to derive properties from one super-class. There are different types of inheritance such as, single, multiple, multi-level, and hybrid inheritance. Inheritance is a very popular property in an object-oriented programming language, such as C++, Java, etc. The diamond problem is a common problem in Java when it comes to inheritance. Hence, it will be good to avoid it for making things simple. It creates problems during various operations, for example, constructor chaining and casting. When we compile the above program, it shows the compiler error, as we have shown below.ĭue to these complications and ambiguities, Java does not support multiple inheritance. Assume that we need to call the display() method by using the object of class D, in this scenario Java compiler does not know which display() method to call. Class D inherits the class B and class C (which is invalid in Java).The display() method of class A is overridden by the class B and class C. Class B and class C inherits the class A.creates ambiguity which display() method to call
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |