dagger

Annotation Type MapKey

@Documented
@Target(value=ANNOTATION_TYPE)
@Retention(value=RUNTIME)
@Beta
public @interface MapKey

It enables to define customized key type annotation for map binding by annotating an annotation of a Map's key type. The defined key type annotation can be later applied to the key of the Map. Currently String and enum key types are supported for map binding.

Example

For example, if you want to define a key type annotation called StringKey, you can define it the following way:

@MapKey(unwrapValue = true)
@Retention(RUNTIME)
public @interface StringKey {
String value();
}

if unwrapValue is false, then the whole annotation will be the key type for the map and annotation instances will be the keys. If unwrapValue is true, the value() type of key type annotation will be the key type for injected map and the value instances will be the keys.

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
boolean	unwrapValue if unwrapValue is false, then the whole annotation will be the type and annotation instances will be the keys.

Element Detail

unwrapValue

public abstract boolean unwrapValue

if unwrapValue is false, then the whole annotation will be the type and annotation instances will be the keys. If unwrapValue is true, the value() type of key type annotation will be the key type for injected map and the value instances will be the keys. Currently only support unwrapValue to be true.

Default:

true