// a wrapper implementation public class ChattyExecutorWrapper implements Executor, Wrapper<Executor> { private final Executor executor; public ChattyExecutorWrapper(Executor executor) { this.executor = executor; } @Override public void execute(Runnable command) { System.out.println("BlaBlaBla..."); executor.execute(command); } @Override public Executor unwrap_() { return executor; } } // another wrapper implementation public class LazyExecutorWrapper implements Executor, Wrapper<Executor>, Attachable<String, String> { private final Executor executor; public LazyExecutorWrapper(Executor executor) { this.executor = executor; } @Override public void execute(Runnable command) { System.out.println("I'm lazy, sleep before work."); sleep(); executor.execute(command); } @Override public Executor unwrap_() { return executor; } private final Attachable<String, String> attachable = new AttachableDelegate<>(); @Override public void setAttachment_(String key, String value) { attachable.setAttachment_(key, value); } @Override public String getAttachment_(String key) { return attachable.getAttachment_(key); } }

public class Demo { public static void main(String[] args) { final Executor executor = buildExecutorChain(); //////////////////////////////////////// // inspect the executor(wrapper chain) //////////////////////////////////////// System.out.println("Is executor lazy? " + containsInstanceTypeOnWrapperChain(executor, LazyExecutorWrapper.class)); // print true String busy = getAttachmentFromWrapperChain(executor, "busy"); System.out.println("Is executor busy? " + busy); // print "very, very busy!" //////////////////////////////////////// // call executor(wrapper chain) //////////////////////////////////////// System.out.println(); executor.execute(() -> System.out.println("I'm working.")); } /**  * prepare executor instances/wrappers, build the executor/wrapper chain  **/ private static Executor buildExecutorChain() { final Executor base = Runnable::run; final LazyExecutorWrapper lazy = new LazyExecutorWrapper(base); lazy.setAttachment_("busy", "very, very busy!"); return new ChattyExecutorWrapper(lazy); } } /* demo output:  Is executor lazy? true Is executor busy? very, very busy!  BlaBlaBla... I'm lazy, sleep before work. I'm working.  */

public class ExistedExecutorWrapper implements Executor { private final Executor executor; public ExistedExecutorWrapper(Executor executor) { this.executor = executor; } @Override public void execute(Runnable command) { System.out.println("I'm existed executor, have nothing to do with ~inspectable~wrappers~."); executor.execute(command); } }

public class IntegrationDemo { public static void main(String[] args) { final Executor executor = buildExecutorChain(); //////////////////////////////////////// // inspect the executor(wrapper chain) //////////////////////////////////////// System.out.println("Is executor ExistedExecutorWrapper? " + containsInstanceTypeOnWrapperChain(executor, ExistedExecutorWrapper.class)); // print true String adaptAttachment = getAttachmentFromWrapperChain(executor, "adapted-existed-executor-wrapper-msg"); System.out.println("Adapted existed executor wrapper msg: " + adaptAttachment); // print "I'm an adapter of an existed executor which have nothing to do with ~inspectable~wrappers~." //////////////////////////////////////// // call executor(wrapper chain) //////////////////////////////////////// System.out.println(); executor.execute(() -> System.out.println("I'm working.")); } private static Executor buildExecutorChain() { final Executor base = Runnable::run; final ExistedExecutorWrapperAdapter adapter = createExistedExecutorWrapperAdapter(base); return new ChattyExecutorWrapper(adapter); } private static ExistedExecutorWrapperAdapter createExistedExecutorWrapperAdapter(Executor base) { final ExistedExecutorWrapper existed = new ExistedExecutorWrapper(base); final ExistedExecutorWrapperAdapter adapter = new ExistedExecutorWrapperAdapter(base, existed); adapter.setAttachment_("adapted-existed-executor-wrapper-msg", "I'm an adapter of an existed executor which have nothing to do with ~inspectable~wrappers~."); return adapter; } /**  * Adaption an existed wrapper(`ExistedExecutorWrapper`) without modifying it.  */ private static class ExistedExecutorWrapperAdapter implements Executor, WrapperAdapter<Executor>, Attachable<String, String> { private final Executor base; private final Executor adaptee; public ExistedExecutorWrapperAdapter(Executor base, Executor adaptee) { this.base = base; this.adaptee = adaptee; } @Override public Executor unwrap_() { return base; } @Override public Executor adaptee_() { return adaptee; } @Override public void execute(Runnable command) { adaptee.execute(command); } private final Attachable<String, String> attachable = new AttachableDelegate<>(); @Override public void setAttachment_(String key, String value) { attachable.setAttachment_(key, value); } @Nullable @Override public String getAttachment_(String key) { return attachable.getAttachment_(key); } } } /* demo output:  Is executor ExistedExecutorWrapper? true Adapted existed executor wrapper msg: I'm an adapter of an existed executor which have nothing to do with ~inspectable~wrappers~.  BlaBlaBla... I'm an adapter of an existed executor which have nothing to do with ~inspectable~wrappers~. I'm working.  */

public class IntegrationDemoUsingWrapperAdapterUtils { public static void main(String[] args) { final Executor executor = buildExecutorChain(); //////////////////////////////////////// // inspect the executor(wrapper chain) //////////////////////////////////////// System.out.println("Is executor ExistedExecutorWrapper? " + containsInstanceTypeOnWrapperChain(executor, ExistedExecutorWrapper.class)); // print true String adaptAttachment = getAttachmentFromWrapperChain(executor, "adapted-existed-executor-wrapper-msg"); System.out.println("Adapted existed executor wrapper msg: " + adaptAttachment); // print "I'm an adapter of an existed executor which have nothing to do with ~inspectable~wrappers~." //////////////////////////////////////// // call executor(wrapper chain) //////////////////////////////////////// System.out.println(); executor.execute(() -> System.out.println("I'm working.")); } private static Executor buildExecutorChain() { final Executor base = Runnable::run; final Executor adapter = createExistedExecutorWrapperAdapter(base); return new ChattyExecutorWrapper(adapter); } private static Executor createExistedExecutorWrapperAdapter(Executor base) { final Executor existed = new ExistedExecutorWrapper(base); Attachable<String, String> attachable = new AttachableDelegate<>(); attachable.setAttachment_("adapted-existed-executor-wrapper-msg", "I'm an adapter of an existed executor which have nothing to do with ~inspectable~wrappers~."); return WrapperAdapterUtils.createWrapperAdapter(Executor.class, base, existed, attachable); } } /* demo output:  Is executor ExistedExecutorWrapper? true Adapted existed executor wrapper msg: I'm an adapter of an existed executor which have nothing to do with ~inspectable~wrappers~.  BlaBlaBla... I'm an adapter of an existed executor which have nothing to do with ~inspectable~wrappers~. I'm working.  */