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    <p>You can solve both problems by using <a href="https://wiki.engr.illinois.edu/download/attachments/220441849/double-dispatch.pdf?version=1&amp;modificationDate=1359481987000" rel="nofollow" title="Double Dispatch">Double Dispatch</a> between the state instances and the <code>superAgent</code> instance to avoid breaking encapsulation.</p> <p>Say you already implemented the State Pattern. <code>instructionResponseRecievedFromAgent</code> would look like:</p> <pre><code>public void instructionResponseRecievedFromAgent() { state.instructionResponseRecievedFromAgent(); } </code></pre> <p>Each <code>State</code> implements <code>instructionResponseRecievedFromAgent</code> using double dispatch this way: </p> <pre><code>abstract class State { abstract void instructionResponseRecievedFromAgent(); } class State1 extends State { void instructionResponseRecievedFromAgent() { // instance variable agent.instructionResponseRecievedFromAgentFromState1(); } } class State1 extends State { void instructionResponseRecievedFromAgent() { // instance variable agent.instructionResponseRecievedFromAgentFromState2(); } } </code></pre> <p>Doing this you let the each <code>State</code> specify <strong>what</strong> to do, but is the <code>superAgent</code> instance who decides <strong>how</strong> to do it. You have full access to the state and locks without making them public. </p> <p>Finally, you implement both <code>instructionResponseRecievedFromAgentFromState1</code> and <code>instructionResponseRecievedFromAgentFromState2</code> in <code>superAgent</code>:</p> <pre><code>public void instructionResponseRecievedFromAgentFromState1() { //this is doState1Behavior original implementation synchronized(instructionLock) { //make state specific modifications to instructionData } } public void instructionResponseRecievedFromAgentFromState2() { //this is doState1Behavior original implementation synchronized(instructionLock) { //make state specific modifications to instructionData } } </code></pre> <p>Keep in mind that, event though <code>instructionResponseRecievedFromAgentFromState1</code> and <code>instructionResponseRecievedFromAgentFromState2</code> are public methods (so the <code>State</code> instances can call them), they're only meant to be used only in the context of the State Pattern.</p>
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    1. COVery interesting way of approaching the problem. This solution is certainly a potential solution to the problem. However, this approach isn't entirely appropriate to my scenario because the "how to do it" methods are still exposed, and they functionality I'm talk about really shouldn't be I solved the problem ultimately by passing 3 reference variables (including the lock) of the super agent to the state class using the constructor, allowing me to mutate them from within the state without exposing them I've still used this approach for some state specific behavior. Very useful suggestion
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    2. COHi! Keep in mind that the exposed methods tells "what" has to be done, the "how" is tied to the way you implement them. About your approach: notice that allowing an object to be mutated from outside by exposing the internal state is not a good idea. Besides dealing with repeated code, for example, you cannot ensure the invariant is not broken. Cheers!
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    3. CO"Notice that allowing an object to be mutated from outside by exposing the internal state is not a good idea" Why is this? All objects are declared final (not that this matters becayse of Java's value references anyway) but I can't see any reason not to do this, besides it not being entirely obvious to maintaining programmers, however if it's well documentent I can't see a problem. Care to elaborate?
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