Apex Asynchronous Processing
In Apex, some operations take time (like API calls, data processing, etc.). To avoid slowing down the user experience, Asynchronous Apex lets you run those operations in the background — after the current process finishes.
Why Use Asynchronous Apex ?
• Long-running operations
• Avoid hitting governor limits
• Improve user experience
• Perform callouts to external systems
1. @future Method
Definition :
Runs a method asynchronously in the background after the current process is complete.
Rules :
• Must be static and return void
• with @future
• Parameters must be primitive data types (no SObjects)
• Can perform callouts if declared with @future(callout=true)
Syntax :
apex
public class FutureExample {
@future
public static void sendWelcomeEmail(String email) {
// Simulate sending email
System.debug(‘Sending email to: ‘ + email);
}
}
How to Call :
apex
FutureExample.sendWelcomeEmail(‘test@example.com’);
With Callout Example :
apex
public class CalloutFutureExample {
@future(callout=true)
public static void callExternalApi(String url) {
Http h = new Http();
HttpRequest req = new HttpRequest();
req.setEndpoint(url);
req.setMethod(‘GET’);
HttpResponse res = h.send(req);
System.debug(‘Response: ‘ + res.getBody());
}
}
Code Explanation
public class FutureExample : {
A class named FutureExample. It holds our future method.
@future
: Marks the method to run asynchronously (in the background).
public static voidsendWelcomeEmail (String email):
A method that takes an email (as a string). It must be static and return void.
System.debug(‘Sending email to: ‘ + email); :
This line prints the email to the debug log. Simulates sending an email.
Practice Tasks :
1. Create a future method that accepts a String name and prints “Hello, [name]” using System.debug().
2. Create a future method with callout=true and fetch any dummy API.
3. Modify your future method to log the date and time when it runs using Datetime.now().
2. Queueable Apex
Definition :
A more flexible way to run async code. You can :
• Chain jobs
• Pass complex data types (like Lists, Maps, SObjects)
• Monitor job status in Apex Jobs
Syntax :
apex
public class MyQueueableJob implements Queueable {
public void execute(QueueableContext context) {
System.debug(‘Running queueable job…’);
}
}
How to Call :
apex
ID jobId = System.enqueueJob(new MyQueueableJob());
Chaining Queueable Jobs:
apex
public class FirstJob implements Queueable {
public void execute(QueueableContext context) {
System.debug(‘First job running…’);
System.enqueueJob(new SecondJob());
}
}
public class SecondJob implements Queueable {
public void execute(QueueableContext context) {
System.debug(‘Second job running…’);
}
}
Passing Data :
apex
public class ProcessAccounts implements Queueable {
List<Account> accounts;
public ProcessAccounts(List<Account> accs) {
this.accounts = accs;
}
public void execute(QueueableContext context) {
for (Account acc : accounts) {
acc.Name = acc.Name + ‘ – Updated’;
}
update accounts;
}
}
apex
List<Account> accs = [SELECT Id, Name FROM Account LIMIT 5];
System.enqueueJob(new ProcessAccounts(accs));
Monitor :
Go to Setup > Apex Jobs to track the job’s progress and outcome.
Practice Tasks :
1. Create a basic Queueable class that prints a message to the debug log.
2. Write a Queueable job that updates the name of 5 Account records by appending “ – VIP”.
3. Chain two Queueable jobs: First one logs “Job 1 started”, the second logs “Job 2 running”.
4. Pass a list of Leads into a Queueable job and mark their status as “Contacted”.
5. Enqueue your Queueable job and store its Job ID. Print it with System.debug().
