Introduction

Queueable Apex is a powerful asynchronous execution framework in Salesforce that allows developers to perform complex and long-running operations. It builds upon the functionality of @future methods and provides additional features like chaining jobs and accessing non-primitive data types.

Key Features of Queueable Apex

• Enables job chaining.
• Allows passing of non-primitive data types.
• Provides better monitoring and debugging capabilities.

Syntax
Queueable Apex classes must implement the Queueable interface.

public class QueueableExample implements Queueable {
    public void execute(QueueableContext context) {
        // Business logic here
        List<Account> accounts = [SELECT Id, Name FROM Account WHERE Industry = 'Technology'];
        for (Account acc : accounts) {
            acc.Name = acc.Name + ' - Updated';
        }
        update accounts;
    }
}

How to Enqueue a Job

QueueableExample job = new QueueableExample();
Id JobId = System.enqueueJob(job);

Chaining Jobs

public class ChainingQueueableExample implements Queueable {
    public void execute(QueueableContext context) {
        // First job logic
        System.enqueueJob(new AnotherQueueableJob());
    }
}

You can monitor Queueable jobs from the Apex Jobs page in Salesforce Setup.

Limitation for Asynchronous