What happens when 2 threads try to modify an ArrayList?

There is no guaranteed behavior for what happens when add is called concurrently by two threads on ArrayList. However, it has been my experience that both objects have been added fine. Most of the thread safety issues related to lists deal with iteration while adding/removing.

When an array is passed to a method will the content of the array undergo changes with the action carried within the function?

If we make a copy of array before any changes to the array the content will not change. Else the content of the array will undergo changes.

Which of these methods can be used to obtain a static array from an ArrayList object?

Discussion Forum

Que.	Which of these methods can be used to obtain a static array from an ArrayList object?
b.	covertArray()
c.	toArray()
d.	covertoArray()
	Answer:toArray()

How do you make an ArrayList thread safe in Java?

The synchronizedList(List) method is used to return a synchronized (thread-safe) list backed by the specified list.

1. import java.util.*;
2. public class SyncronizeArrayList {
3. public static void main(String args[]) {
4. // Non Synchronized ArrayList.
5. List fruitList = new ArrayList();
6. fruitList.add(“Mango”);

What is CopyOnWriteArrayList in Java?

CopyOnWriteArrayList is a thread-safe variant of ArrayList where operations which can change the ArrayList (add, update, set methods) creates a clone of the underlying array. CopyOnWriteArrayList is to be used in a Thread based environment where read operations are very frequent and update operations are rare.

What is the difference between ArrayList and LinkedList Mcq?

1) ArrayList internally uses a dynamic array to store the elements. LinkedList internally uses a doubly linked list to store the elements. 3) An ArrayList class can act as a list only because it implements List only. LinkedList class can act as a list and queue both because it implements List and Deque interfaces.

When an array is passed to a method?

When we pass an array to a method as an argument, actually the address of the array in the memory is passed (reference). Therefore, any changes to this array in the method will affect the array.

Which of these methods of ArrayList class is used to obtain the length of an object?

The size() method of java. util. ArrayList class is used to get the number of elements in this list.

Which of the following options are properties of ArrayList in Java?

An ArrayList has these characteristics:

• An ArrayList automatically expands as data is added.
• Access to any element of an ArrayList is O(1). Insertions and deletions are O(N).
• An ArrayList has methods for inserting, deleting, and searching.
• An ArrayList can be traversed using a foreach loop, iterators, or indexes.

What is thread safe ArrayList in Java?

A thread-safe variant of ArrayList in which all mutative operations (e.g. add, set, remove..) are implemented by creating a separate copy of underlying array. It achieves thread-safety by creating a separate copy of List which is a is different way than vector or other collections use to provide thread-safety.

How can we synchronize ArrayList in Java?

In order to get a synchronized list from an ArrayList, we use the synchronizedList(List ) method in Java. The Collections. synchronizedList(List ) method accepts the ArrayList as an argument and returns a thread safe list.

What happens when add is called by two threads on ArrayList?

There is no guaranteed behavior for what happens when add is called concurrently by two threads on ArrayList. However, it has been my experience that both objects have been added fine. Most of the thread safety issues related to lists deal with iteration while adding/removing.

How does ArrayList get out of sync?

If multiple threads access an ArrayList instance concurrently, and at least one of the threads modifies the list structurally, it must be synchronized externally. Since there is no synchronization internally, what you theorize is not plausible. So, things get out of sync, with unpleasant and unpredictable results.

What are the thread safety issues with ArrayList?

Most of the thread safety issues related to lists deal with iteration while adding/removing. Despite this, I strongly recommend against using vanilla ArrayList with multiple threads and concurrent access.

What happens when multiple threads write at the same time?

There can also be odd behaviors with multiple readers when one or more threads is writing at the same time. Note that this implementation is not synchronized. If multiple threads access an ArrayList instance concurrently, and at least one of the threads modifies the list structurally, it must be synchronized externally.