Java – how many elements does ArrayList add when it resizes itself?

Java's ArrayList dynamically extends itself when needed How many elements will it add when the extension occurs?

Does it copy the old array into the new array, or does it connect the two together in some way?

Solution

Look at the source code:

int newCapacity = (oldCapacity * 3)/2 + 1;

The exact factors vary from implementation to implementation, and GNU use factor 2 It doesn't matter. It just trades memory for speed

It copies all elements into a new array