java-annotations

Using Room’s @ForeignKey as @Entity parameter in Kotlin

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This is the way to provide the annotation you’re looking for, with explicit arrays for the arguments, and no @ for the nested annotation’s creation: @Entity(tableName = “Foo”, foreignKeys = arrayOf( ForeignKey(entity = Bar::class, parentColumns = arrayOf(“someCol”), childColumns = arrayOf(“someOtherCol”), onDelete = CASCADE))) Since Kotlin 1.2, you can also use array literals: @Entity(tableName = “Foo”, … Read more

Difference between @EntityScan and @ComponentScan

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The @ComponentScan annotation is used to automatically create beans for every class annotated with @Component, @Service, @Controller, @RestController, @Repository, … and adds them to the Spring container (allowing them to be @Autowired). The @EntityScan on the other hand does not create beans as far as I know. It only identifies which classes should be used … Read more

Is a Python Decorator the same as Java annotation, or Java with Aspects?

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Python decorators are just syntactic sugar for passing a function to another function and replacing the first function with the result: @decorator def function(): pass is syntactic sugar for def function(): pass function = decorator(function) Java annotations by themselves just store metadata, you must have something that inspects them to add behaviour.   Java AOP … Read more

what is the use of annotations @Id and @GeneratedValue(strategy = GenerationType.IDENTITY)? Why the generationtype is identity?

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First of all, using annotations as our configure method is just a convenient method instead of coping the endless XML configuration file. The @Idannotation is inherited from javax.persistence.Id， indicating the member field below is the primary key of current entity. Hence your Hibernate and spring framework as well as you can do some reflect works … Read more