What are the advantages and disadvantages of using ArrayList in Java?

Advantages of ArrayList in Java:

• Dynamic size: ArrayList automatically increases its size when elements are added.
• Fast access by index: get and set operations are performed in constant time O(1).
• Ease of use: implements the List interface, supporting many methods for working with collections.

Disadvantages of ArrayList:

• Slow insertion/deletion in the middle of the list: insert and delete operations require shifting elements, which takes O(n).
• Not synchronized: not suitable for multithreaded access without external synchronization.
• Cost of resizing: when the internal array overflows, elements are copied to a new array.

Example usage:

ArrayList<String> list = new ArrayList<>();
list.add("Java");
list.add("Python");
String lang = list.get(0); // "Java"

If frequent insertion/deletion in the middle is needed, it is better to use LinkedList.