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copied!<p>It seems to me like you need a scope for each instance of <code>RootObject</code> and all its dependencies.</p> <p>In Guice you can create a custom scope, say <code>@ObjectScoped</code>, like this:</p> <pre class="lang-java prettyprint-override"><code>@Target({ TYPE, METHOD }) @Retention(RUNTIME) @ScopeAnnotation public @interface ObjectScoped {} </code></pre> <p>Now just place <code>RootObject</code>, <code>A</code>, <code>B</code> and <code>D</code> into this scope:</p> <pre class="lang-java prettyprint-override"><code>@ObjectScoped public class RootObject { private A a; private B b; @Inject public RootObject(A a, B b) { this.a = a; this.b = b; } public A getA() { return a; } public B getB() { return b; } } @ObjectScoped public class A { private D d; @Inject public A(D d) { this.d = d; } public D getD() { return d; } } // The same for B and D </code></pre> <p>Now each <code>RootObject</code> has its own scope. You can implement this as a simple <code>HashMap</code>:</p> <pre class="lang-java prettyprint-override"><code>public class ObjectScope { private Map<Key<?>,Object> store = new HashMap<Key<?>,Object>(); @SuppressWarnings("unchecked") public <T> T get(Key<T> key) { return (T)store.get(key); } public <T> void set(Key<T> key, T instance) { store.put(key, instance); } } </code></pre> <p>To integrate these scopes with Guice you will need a <code>com.google.inject.Scope</code>-implementation which lets you switch the scopes and the corresponding wiring in your <code>Module</code>.</p> <pre class="lang-java prettyprint-override"><code>public class GuiceObjectScope implements Scope { // Make this a ThreadLocal for multithreading. private ObjectScope current = null; @Override public <T> Provider<T> scope(final Key<T> key, final Provider<T> unscoped) { return new Provider<T>() { @Override public T get() { // Lookup instance T instance = current.get(key); if (instance==null) { // Create instance instance = unscoped.get(); current.set(key, instance); } return instance; } }; } public void enter(ObjectScope scope) { current = scope; } public void leave() { current = null; } } public class ExampleModule extends AbstractModule { private GuiceObjectScope objectScope = new GuiceObjectScope(); @Override protected void configure() { bindScope(ObjectScoped.class, objectScope); // your bindings } public GuiceObjectScope getObjectScope() { return objectScope; } } </code></pre> <p>Initialize your program like this:</p> <pre class="lang-java prettyprint-override"><code>ExampleModule module = new ExampleModule(); Injector injector = Guice.createInjector(module); GuiceObjectScope objectScope = module.getObjectScope(); </code></pre> <p>Create the first instance of <code>RootObject</code> and its corresponding scope:</p> <pre class="lang-java prettyprint-override"><code>ObjectScope obj1 = new ObjectScope(); objectScope.enter(obj1); RootObject rootObject1 = injector.getInstance(RootObject.class); objectScope.leave(); </code></pre> <p>Just switch the scope for a second group of objects:</p> <pre class="lang-java prettyprint-override"><code>ObjectScope obj2 = new ObjectScope(); objectScope.enter(obj2); RootObject rootObject2 = injector.getInstance(RootObject.class); objectScope.leave(); </code></pre> <p>Test if your requirements are met:</p> <pre class="lang-java prettyprint-override"><code>assert rootObject1 != rootObject2; assert rootObject1.getA() != rootObject2.getA(); assert rootObject1.getA().getD() == rootObject1.getB().getD(); assert rootObject1.getA().getD() != rootObject2.getB().getD(); </code></pre> <p>To work with a group of objects just enter its scope and use the injector:</p> <pre class="lang-java prettyprint-override"><code>objectScope.enter(obj1); B b1 = injector.getInstance(B.class); objectScope.leave(); assert rootObject1.getB() == b1; </code></pre>

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