How to Implement a Thread-Safe Resizable Array in Java

In using a thread-safe resizable array, several threads are able to execute operations like insertion and deletion without running the risk of data corruption. Though it is a standard Java class, the ArrayList class is not thread-safe by default. Concurrent collections or synchronization could be used to ensure thread safety. We can generate a thread-safe resizable array by using concurrent collections such as Collections.synchronizedList or CopyOnWriteArrayList. By ensuring that only a single thread may access the variety at a time, synchronization helps prevent data corruption.

In Java, you can use synchronization methods to handle concurrent modifications and ensure safe scaling when implementing a thread-safe resizable array.

Different methods for implementing a Thread-Safe Resizable Array:

Approach: Use synchronized methods

For the array to be modified by a single thread at a time, synchronize the methods that add, remove, and resize elements.

In this example, a thread-safe resizable array is created using Collections. synchronized list. The synchronizedList function creates a synchronized (thread-safe) list by wrapping an existing list.

Implementation:

FileName: ThreadSynchronizedList.java

Output:

 The elements present in the array is: 10 20 30 40 50 

Approach: Use CopyOnWriteArrayList

Here is a resizable, thread-safe array that comes with Java thanks to the java.util.concurrent package. Every time a change is made, a new copy of the underlying array is created to guarantee thread safety. However, for lists that are updated regularly, this may use a lot of memory.

Thread safety is provided by concurrent collections, such as CopyOnWriteArrayList, which do not require explicit synchronization. Every time an element is added or modified; a new duplicate of the underlying array is created to ensure a safe iteration.

Implementation:

FileName: ThreadCopyWriteArrayList.java

Output:

 The elements present in the array is: 10 20 30 40 50 

Approach: Use ReentrantLock

In order to provide safe concurrent access, the code defines a resizable, thread-safe array in Java utilizing generics and a ReentrantLock. In order to store generic elements (T), the class ThreadSafeResizableArray contains a constructor that initializes the array with a specified initial capacity. The array's capacity is doubled by copying existing items to a new, more enormous array when the add method, which is locked, adds elements to the array.

If the array's current size exceeds its limit, the resize function is triggered. In addition to using locking to maintain thread safety when managing possible IndexOutOfBoundsExceptions, the get function permits the retrieval of elements at specified indices.

Implementation:

FileName: ThreadSafeResizableArray.java

Output:

 The elements in the array is: 10 20 30 40 50