java - Instantiate an extended class or its parent (depending on circumstances) -

let's have class named human in projecta. instantiated in creaturebuilder class of same project.

now want create new class called cyborg in different project, i.e. in projectb. projectb has projecta in imports, projecta knows nothing projectb.

cyborg extends human, , must instantiated creaturebuilder of projecta (so, cyborg located in projectb, call creaturebuilder projectb instantiate cyborg, creaturebuilder located in projecta, human class).

i need logic create human when creaturebuilder instantiated projecta, , create cyborg when creaturebuilder instantiated projectb.

i think achievable creating interface getcreature() method in projecta. method overridden in projectb return new cyborg , passed creaturebuilder of projecta. other suggestions? think best workaround? can use reflection api instead?

cheers!

java 8

creaturebuilder can delegate creature's creation caller asking supplier.

public class creaturebuilder {     public creature getcreature(supplier<creature> creaturesupplier)     {         //do unknown things         return creaturesupplier.get();     } } 

usage projecta

public class projecta {     public static void main(string[] args) {         creature = new creaturebuilder().getcreature(human::new);     } } 

usage projectb

public class projectb {     public static void main(string[] args) {         creature b = new creaturebuilder().getcreature(cyborg::new);     } } 

and never use reflection if you're not forced to.

java 7

if you're sticked java 7, principle remains same except it's bit more verbose.

you have declare , use own supplier-like interface

public interface creaturesupplier {     creature get(); }  public class creaturebuilder {     public creature getcreature(creaturesupplier creaturesupplier)     {         //do things         return creaturesupplier.get();     } } 

usage bit more verbose

public class projecta {     public static void main(string[] args) {         creature = new creaturebuilder().getcreature(new creaturesupplier() {             @override             public creature get() {                 return new human();             }         });     } }  public class projectb {     public static void main(string[] args) {         creature b = new creaturebuilder().getcreature(new creaturesupplier() {             @override             public creature get() {                 return new cyborg();             }         });     } } 

and... that's it, you've got same behaviour 1 in java 8.