Collection of Java arrays

I. ArrayList

1. The ArrayList is implemented in an array, and when a ArrayList object is generated using a constructor without parameters, an array of type object of length 10 is actually generated at the bottom
2. If the number of added elements exceeds 10, then the ArrayList layer will be reborn into an array, 1.5 times times the length of the original array +1, then copy the contents of the original array into the new array, and the subsequent additions will be placed in the new array. This procedure is repeated when the new array cannot accommodate the added element.
3. For the delete operation of the ArrayList element, the subsequent elements of the deleted element need to be moved forward, at a higher cost.
4. The collection can only be placed in the object reference, unable to place the native data type, we need to use the native data type wrapper class to join the collection.
5. The object type is placed in the collection, so the object type is taken out, so it must be converted to the true type using the coercion type conversion (the type to put in).

Collection of Java arrays