ArrayLists
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Storing Numbers in ArrayLists
Remember the differences between primitives and objects? ArrayLists can only store Objects. If we want to store a primitive, we have to wrap it in a wrapper class. A wrapper class is essentially an object that stores, or 'wraps', a primitive value so that it can be treated more like an object.
There are wrappers for the primitives.
Most wrappers have a method that starts with parse to turn a String into a primitive of that type. They also have a method ending in Value that returns the primitive type. To create a wrapper object for a given primitive type, pass the primitive, or a String representation of the primitive, into the constructor for the wrapper.