JBoss Weld CDI for Java Platform

Qualifiers

A qualifier is an annotation that has @Qualifier declared on it, which signifies to the container that this qualifier annotation can be utilized on injection points and beans to distinguish different implementations of the same bean type.

A qualifier annotation, without any members, is just:

@Qualifier
@Retention(RUNTIME)
@Target( { TYPE, METHOD, FIELD, PARAMETER } )
public @interface MyQualifier {}

Note

@MyQualifier has been defined for use on a Java type, method, field, or method parameter.

We can use field injection with @MyQualifier by:

@Inject
@MyQualifier
private Locale myLocale;

Or constructor injection:

@Inject
public Notifications(@MyQualifier Locale myLocale) {
  this.myLocale = myLocale;
}

Or an initializer method:

@Inject public void ...