What s the difference between interface and interface in java

Question

I haven t touched Java since using JBuilder in the late 90 s while at University  so I m a little out of touch - at any rate I ve been working on a small Java project this week  and using Intellij IDEA as my IDE  for a change of pace from my regular  Net development   I notice it has support for adding interfaces and  interfaces  what is an  interface  and how does it differ from a normal interface   public interface Test       vs   public  interface Test       I ve done a bit of searching  but couldn t find a great deal of useful info referring to  interface

User · Answer

The interface keyword indicates that you are declaring a traditional interface class in Java  The  interface keyword is used to declare a new annotation type     See docs oracle tutorial on annotations for a description of the syntax  See the JLS if you really want to get into the details of what  interface means

User · Answer

The   symbol denotes an annotation type definition   That means it is not really an interface  but rather a new annotation type -- to be used as a function modifier  such as  override   See this javadocs entry on the subject

User · Answer

interface   In general  an interface exposes a contract without exposing the underlying implementation details  In Object Oriented Programming  interfaces define abstract types that expose behavior  but contain no logic  Implementation is defined by the class or type that implements the interface    interface    Annotation type   Take the below example  which has a lot of comments   public class Generation3List extends Generation2List          Author  John Doe       Date  3 17 2002       Current revision  6       Last modified  4 12 2004       By  Jane Doe       Reviewers  Alice  Bill  Cindy        class code goes here      Instead of this  you can declare an annotation type    interface ClassPreamble      String author       String date       int currentRevision   default 1     String lastModified   default  N A      String lastModifiedBy   default  N A         Note use of array    String   reviewers        which can then annotate a class as follows     ClassPreamble      author    John Doe      date    3 17 2002      currentRevision   6     lastModified    4 12 2004      lastModifiedBy    Jane Doe         Note array notation    reviewers     Alice    Bob    Cindy     public class Generation3List extends Generation2List       class code goes here      PS  Many annotations replace comments in code   Reference  http   docs oracle com javase tutorial java annotations declaring html

User · Answer

interface   defines the contract for a class which implements it   interface  defines the contract for an annotation

User · Answer

interface in the Java programming language is an abstract type that is used to specify a behavior that classes must implement  They are similar to protocols  Interfaces are declared using the interface keyword   interface is used to create your own  custom  Java annotations  Annotations are defined in their own file  just like a Java class or interface  Here is custom Java annotation example    interface MyAnnotation        String   value         String   name        int      age        String   newNames         This example defines an annotation called MyAnnotation which has four elements  Notice the  interface keyword  This signals to the Java compiler that this is a Java annotation definition   Notice that each element is defined similarly to a method definition in an interface  It has a data type and a name  You can use all primitive data types as element data types  You can also use arrays as data type  You cannot use complex objects as data type   To use the above annotation  you could use code like this    MyAnnotation      value  123       name  Jakob       age 37      newNames   Jenkov    Peterson     public class MyClass         Reference - http   tutorials jenkov com java annotations html

[java] What's the difference between interface and @interface in java?

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