Ever since JDK 8 has allowed concrete (non-abstract) methods on the interface similar default as well as static methods, many of my readers accept asked me how should they response the classical abstract shape vs interface questions. Earlier, an interface cannot accept whatsoever concrete methods as well as that was the head divergence betwixt abstract shape as well as interface but at ane time that is non the case. In this post, I'll revisit this hugely pop Java interview enquiry inward lite of Java 8 changes. As I said, earlier JDK 8, the degree of abstraction was the clear-cut divergence betwixt abstract shape as well as interface similar interface was the purest shape of Abstraction which solely defines what interface is supposed to create without specifying how they should last implemented, inward other words, it solely declares API methods as well as leaves implementation to its subclasses.
But, the head divergence betwixt an abstract shape as well as interface inward Java 8 is the fact that an abstract shape is a shape as well as an interface is an interface. Influenza A virus subtype H5N1 shape tin strength out accept a soil which tin strength out last modified past times non-abstract methods but an interface cannot accept the state because they can't accept instance variables.
The mo divergence is that an interface cannot accept a constructor fifty-fifty inward Java 8 but y'all may recall that abstract shape tin strength out besides accept a constructor in Java. All methods of an interface were abstract but since Java 8 y'all tin strength out define non-abstract methods inward the shape of default as well as static methods within interface inward Java.
This brings many questions to come upwardly to mind, which we'll hash out inward the adjacent section, btw, if y'all are novel to Java footing as well as only started learning Java, I propose y'all exercise a course of teaching which is up-to-date like The Complete Java MasterClass on Udemy because Java is changing really fast. In only a yr nosotros accept moved from Java nine to Java 12. Thankfully this course of teaching is up-to-date as well as the writer tries to update it alongside every Java release.
Well, I believe they are for ii unlike purposes as well as nosotros volition larn to a greater extent than ane time nosotros starting fourth dimension using Java 8 regularly, but next semantics divergence betwixt abstract shape as well as interface alongside default method volition direct y'all farther :
1) Abstract classes are classes, so they are non restricted to other restrictions of the interface inward Java e.g. abstract shape tin strength out accept the state, but y'all cannot accept the soil on the interface inward Java.
2) Another semantic divergence betwixt interface alongside default methods as well as abstract shape is that y'all can define constructors within an abstract class, but y'all cannot define constructor within interface inward Java.
In reality, default or defender methods are introduced to keep backward compatibility as well as same fourth dimension making Collection API to a greater extent than suitable to last used within telephone commutation Java 8 features similar lambda expressions.
Without adding default methods, it wasn't possible to declare whatsoever novel method on the existing interface inward Java without breaking all classes which implement it, but because of default method, y'all tin strength out at ane time improve evolve your API.
They defend your code against implementing novel methods thence they are besides called defender methods. If y'all desire to know to a greater extent than most default methods or novel changes inward Java 8 inward general, I propose y'all banking concern tally out the static methods within interface as well as their usage volition evolve ane time Java 8 croak a mainstream Java evolution version, but y'all must recall that an abstract shape is a shape as well as an interface is an interface.
The telephone commutation divergence is that abstract shape tin strength out keep soil but the interface cannot, as well as an abstract shape tin strength out besides accept a constructor which is non allowed within interface fifty-fifty inward Java 8. If y'all are designing API as well as then exercise interface as well as if y'all are abstracting both soil as well as demeanor as well as then exercise an abstract class.
Further Reading
Java SE 8 New Features
books)How to bring together String inward Java 8 (example) How to exercise filter() method inward Java 8 (tutorial) How to format/parse the appointment alongside LocalDateTime inward Java 8? (tutorial) How to exercise Stream shape inward Java 8 (tutorial) How to exercise forEach() method inward Java 8 (example) How to convert List to Map inward Java 8 (solution) 20 Examples of Date as well as Time inward Java 8 (tutorial) How to exercise peek() method inward Java 8 (example) How to kind the map past times keys inward Java 8? (example) How to kind the may past times values inward Java 8? (example) 10 examples of Options inward Java 8? (example) How to convert lambda human face to method reference inward Java 8 (tutorial) 5 Free Java 8 and Java nine courses for Programmers (courses) Thanks for reading this article so far. If y'all similar this article as well as then delight percentage alongside your friends as well as colleagues. If y'all accept whatsoever enquiry or feedback as well as then delight driblet a comment.
But, the head divergence betwixt an abstract shape as well as interface inward Java 8 is the fact that an abstract shape is a shape as well as an interface is an interface. Influenza A virus subtype H5N1 shape tin strength out accept a soil which tin strength out last modified past times non-abstract methods but an interface cannot accept the state because they can't accept instance variables.
The mo divergence is that an interface cannot accept a constructor fifty-fifty inward Java 8 but y'all may recall that abstract shape tin strength out besides accept a constructor in Java. All methods of an interface were abstract but since Java 8 y'all tin strength out define non-abstract methods inward the shape of default as well as static methods within interface inward Java.
This brings many questions to come upwardly to mind, which we'll hash out inward the adjacent section, btw, if y'all are novel to Java footing as well as only started learning Java, I propose y'all exercise a course of teaching which is up-to-date like The Complete Java MasterClass on Udemy because Java is changing really fast. In only a yr nosotros accept moved from Java nine to Java 12. Thankfully this course of teaching is up-to-date as well as the writer tries to update it alongside every Java release.
Difference betwixt Abstract shape vs Interface inward Java 8
Prima facia, in Java 8, an interface looks similar an abstract class as well as ane tin strength out argue about, can nosotros exercise interface alongside default methods inward house of an abstract shape inward Java?Well, I believe they are for ii unlike purposes as well as nosotros volition larn to a greater extent than ane time nosotros starting fourth dimension using Java 8 regularly, but next semantics divergence betwixt abstract shape as well as interface alongside default method volition direct y'all farther :
1) Abstract classes are classes, so they are non restricted to other restrictions of the interface inward Java e.g. abstract shape tin strength out accept the state, but y'all cannot accept the soil on the interface inward Java.
2) Another semantic divergence betwixt interface alongside default methods as well as abstract shape is that y'all can define constructors within an abstract class, but y'all cannot define constructor within interface inward Java.
In reality, default or defender methods are introduced to keep backward compatibility as well as same fourth dimension making Collection API to a greater extent than suitable to last used within telephone commutation Java 8 features similar lambda expressions.
Without adding default methods, it wasn't possible to declare whatsoever novel method on the existing interface inward Java without breaking all classes which implement it, but because of default method, y'all tin strength out at ane time improve evolve your API.
They defend your code against implementing novel methods thence they are besides called defender methods. If y'all desire to know to a greater extent than most default methods or novel changes inward Java 8 inward general, I propose y'all banking concern tally out the static methods within interface as well as their usage volition evolve ane time Java 8 croak a mainstream Java evolution version, but y'all must recall that an abstract shape is a shape as well as an interface is an interface.
The telephone commutation divergence is that abstract shape tin strength out keep soil but the interface cannot, as well as an abstract shape tin strength out besides accept a constructor which is non allowed within interface fifty-fifty inward Java 8. If y'all are designing API as well as then exercise interface as well as if y'all are abstracting both soil as well as demeanor as well as then exercise an abstract class.
Further Reading
Java SE 8 New Features
books)
P. S. - If your finish is to larn novel features introduced inward Java 8 as well as then y'all tin strength out besides banking concern tally out the Java SE 8 New Features course on Udemy which solely focuses on novel features as well as null else.
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