6. What is the difference between Vector, ArrayList and LinkedList?(design, performance, safety)

All implement the list interface, providing corresponding methods for adding, getting, and deleting objects, etc.

One, low-level design implementation, security, performance

Vector: The low-level implementation is implemented with an array, which is thread-safe, but inefficient. It is suitable for use in multiple threads, often reads objects, and uses less insertion and deletion.

ArrayList: The low-level implementation is implemented using an array, which is thread-unsafe and efficient. It is suitable for use in a single thread, often reads objects, and uses less insertion and deletion.

LinkedList: The low-level is implemented by a doubly linked list, which is not thread-safe and is suitable for reading less, frequently inserting and deleting objects.

Second, initial value, expansion multiple and expansion factor

Vector: 10 size+size*0.5+1= size*1.5+1 1

ArrayList: 10 size+size*1= 2*size 0.75

LinkedList: No expansion required, linked list implementation, dynamic expansion.