There are certain cases where in static attributes need to be dependency injected. Let us consider one such case. FlightUtils is a utility class providing a static method parseDate to parse a String in a given format and return the date. The format String is hardcoded in this API. Let us try to inject it statically.
Let us create a private static String attribute dateFormat and create its getter and setter. Mark the setter for injection with a @Named parameter.
@Inject
public static void setDateFormat(
@Named("df")String dateFormat){
FlightUtils.dateFormat = dateFormat;
}Next, prepare a module for FlightUtils:
class FlightUtilityModule extends AbstractModule{
@Override
protected void configure() {
bindConstant().annotatedWith(
Names.named(dateFormat)).to(dd-MM-yy);
requestStaticInjection(FlightUtils.class);
}
}Static injection comes into picture, (if requested) immediately once the injector instance is returned. Hence, we need not invoke the .getInstance...