Different types of Exceptions in Salesforce

Salesforce offers a variety of exceptions that developers might encounter when working with its Apex programming language. Understanding these exceptions and how to handle them is crucial for robust and error-free Salesforce development. Here’s an exhaustive list of common Salesforce exceptions, along with code examples that could potentially result in each exception, and best practices for handling them.

1. QueryException

• Cause: Occurs when there is an issue with a SOQL query, such as an incorrect query syntax or querying for fields that don’t exist.
• Example:

  List<Account> accounts = [SELECT NonExistingField FROM Account];
  

   

  Best Practice: Always verify your SOQL queries in the Developer Console and ensure field names and objects exist and are correctly spelled.

2. DmlException

• Cause: Happens when a DML (Data Manipulation Language) operation (insert, update, delete) fails.
• Example:

  Account acc = new Account();
  insert acc; // Fails because mandatory fields are not set
  

  Best Practice: Ensure all mandatory fields are set before performing DML operations and use try-catch blocks to handle these exceptions.

3. NullPointerException

• Cause: Occurs when trying to access a method or property of an object that is null.
• Example:

  Account acc;
  System.debug(acc.Name); // Throws NullPointerException
  

  Best Practice: Always check if an object is null before accessing its properties or methods.

4. ListException

• Cause: Triggered when there is an issue with list operations, like accessing an index out of bounds.
• Example:

  List<Integer> numbers = new List<Integer>{1, 2, 3};
  Integer num = numbers[3]; // Index out of bounds
  

  Best Practice: Check the size of the list before accessing elements by index.

5. LimitException

• Cause: Salesforce has strict Governor Limits, and this exception is thrown when these limits are exceeded.
• Example:

  for(Integer i=0; i<100000; i++){
      Account acc = new Account(Name='Test'+i);
      insert acc; // Exceeds DML limits
  }
  

  Best Practice: Always be aware of Governor Limits and write optimized code to stay within limits.

6. NoSuchElementException

• Cause: Thrown when attempting to access an element in a collection that doesn’t exist.
• Example:

  Iterator<Account> it = [SELECT Id FROM Account].iterator();
  while(true) {
      Account acc = it.next(); // Fails when there are no more elements
  }
  

  Best Practice: Check if the next element exists using iterator.hasNext() before calling next().

7. TypeException

• Cause: Occurs when there is a mismatch in data types, like assigning a string to an integer.
• Example:

  Integer num = '123'; // Type mismatch
  

  Best Practice: Ensure data types are compatible when assigning values.

8. MathException

• Cause: Triggered by mathematical errors, such as division by zero.
• Example:

  Integer a = 1 / 0; // Division by zero
  

  Http http = new Http();
  HttpRequest request = new HttpRequest();
  request.setEndpoint('https://nonexistent.example.com');
  HttpResponse response = http.send(request); // Fails if the endpoint is not reachable
  

  Best Practice: Check for divisor being zero before division and handle other mathematical edge cases.

9. LockException

• Cause: Happens when there is a record locking issue, often in concurrent data operations.
• Example:

  // Assuming two different processes are updating the same record at the same time
  Account acc = [SELECT Id FROM Account LIMIT 1 FOR UPDATE];
  update acc;
  

  Best Practice: Design your logic to handle record locking and concurrency appropriately.

10. CalloutException

• Cause: Occurs when there is an issue with an external callout, like a timeout or authentication error.
• Example:

    Http http = new Http();
    HttpRequest request = new HttpRequest();
    request.setEndpoint('https://nonexistent.example.com');
    HttpResponse response = http.send(request); // Fails if the endpoint is not reachable
    ```
  

  Best Practice: Handle exceptions for external callouts and check endpoint availability and correctness.