Using a Variable or Array Element That Is Uninitialized and Unassigned

• When an array of objects is instantiated, objects within the array are not instantiated automatically, but all the references get the default value of null.
• When an array of primitives is instantiated, elements get default values.
• Instance variables are always initialized with a default value.
• Local/automatic/method variables are never given a default value. If you attempt to use one before initializing it, you'll get a compiler error.