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copied!<p>Use Interfaces. B's relationship with A is only via an Interface that B defines and A implements.</p> <p>So from B's perspective, it doesn't even import A, or have access to the definition of A at compilation time. </p> <p>Edited in response to question.</p> <p>I beleive you have a class C</p> <p>pre-existing, unchangable by you, code in some package x.y;</p> <pre><code>Class CEvent { // some event definition }; Class C { public void callWhenitHappens(CEvent theEvent) { // do something } } </code></pre> <p>--- code you write ---</p> <pre><code>package p.q; public Class A implements BEventInterface { public void bEventHappened( BEvent theBEvent ){ // make a C event myC.callWhenitHappens(theCEvent); } } </code></pre> <p>And your concern is that <strong>anybody</strong>, even including C could call that bEventHappened() method.</p> <p>My feeling is that you're concerned by an unlikely problem. Why would someone go to the trouble of creating an A object and doing that? However there are some possibilities:</p> <p>1). If A and B are in the same package, do not make A and it's method public. Only B needs to see them, so at package scope this will just work.</p> <p>2). Anonymous inner class. Note here that A ia class with a no public methods, so C can't use it and yet B has public methods on the anonymous inner class it can use. </p> <pre><code>package p.q; import p.q.B.BEvent; import x.y.z.C.CEvent; import x.y.z.C; public class A { // anonymous class implementing required interface private BListener myFacade = new BListener(){ @Override public void listen(BEvent event) { bEventHappened(event); } }; private B myB; private C myC; A() { myC = new C(); myB = new B(); myB.registerListener(myFacade); } private void bEventHappened( BEvent theBEvent ){ myC.callWhenitHappens(myC.new CEvent() ); } } </code></pre> <p>With classes B and C looking like:</p> <pre><code>package p.q; public class B { public class BEvent { public String what; } private BListener myListener; private void fireEvent(){ myListener.listen(new BEvent()); } public void registerListener(BListener listener){ myListener = listener; } } </code></pre> <p>and</p> <pre><code>package x.y.z; public class C { public class CEvent { public String what; } public void callWhenitHappens(CEvent event){ //e3c } </code></pre> <p>}</p>

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