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    <p>What actually causes a java.lang.StackOverflowError is typically unintentional recursion. For me it's often when I intended to call a super method for the overidden method. Such as in this case:</p> <pre><code>public class Vehicle { public void accelerate(float acceleration, float maxVelocity) { // set the acceleration } } public class SpaceShip extends Vehicle { @Override public void accelerate(float acceleration, float maxVelocity) { // update the flux capacitor and call super.accelerate // oops meant to call super.accelerate(acceleration, maxVelocity); // but accidentally wrote this instead. A StackOverflow is in our future. this.accelerate(acceleration, maxVelocity); } } </code></pre> <p>First, it's useful to know what happens behind the scenes when we call a function. The arguments and the address of where the method was called is pushed on the stack (see <a href="http://en.wikipedia.org/wiki/Stack_(abstract_data_type)#Runtime_memory_management">http://en.wikipedia.org/wiki/Stack_(abstract_data_type)#Runtime_memory_management</a>) so that the called method can access the arguments and so that when the called method is completed, execution can continue after the call. But since we are calling this.accelerate(acceleration, maxVelocity) recursively (recursion is loosely when a method calls itself. For more info see <a href="http://en.wikipedia.org/wiki/Recursion_(computer_science)">http://en.wikipedia.org/wiki/Recursion_(computer_science)</a>) we are in a situation known as infinite recursion and we keep piling the arguments and return address on the call stack. Since the call stack is finite in size, we eventually run out of space. The running out of space on the call stack is known as overflow. This is because we are trying to use more stack space than we have and the data literally overflows the stack. In the Java programming language, this results in the runtime exception java.lang.StackOverflow and will immediately halt the program. </p> <p>The above example is somewhat simplified (although it happens to me more than I'd like to admit.) The same thing can happen in a more round about way making it a bit harder to track down. However, in general, the StackOverflow is usually pretty easy to resolve, once it occurs.</p> <p>In theory, it is also possible to have a stack overflow without recursion, but in practice, it would appear to be a fairly rare event.</p>
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