Annotate Required Field Lease For Free

We can enable @Required annotation in two ways in Spring XML configuration: Either by registering RequiredAnnotationBeanPostProcessor in the bean definition. Or can be implicitly registered by including the <context:annotation-config/> tag in an XML-based Spring configuration.

Annotations are used to provide supplemental information about a program. Annotations start with '@'. Annotations do not change the action of a compiled program. Annotations help to associate metadata (information) to the program elements i.e. instance variables, constructors, methods, classes, etc.

@Nullable and @NotNull ? indicate a variable, parameter, or return value that can or cannot be null. @Nls ? indicates that an annotated code element is a string that needs to be localized.

The @Required annotation in spring is a method-level annotation used in the setter method of a bean property and therefore making the setter-injection compulsory.

Press Ctrl Alt 0S to open the IDE settings and then select Build, Execution, Deployment | Compiler | Annotation Processors.

Use @Field to define a structured data type's field name for an object mapped to NoSql data. Table 2-24 describes this annotation's elements. (Optional) The data type's name of the field. The @Field annotation is a generic form of the @Column annotation, which is not specific to relational databases.

The @Required annotation applies to bean property setter methods and it indicates that the affected bean property must be populated in XML configuration file at configuration time. Otherwise, the container throws a BeanInitializationException exception. Following is an example to show the use of @Required annotation.