Apex Exceptions

Question 1

List some apex exceptions

Answer 1

• DmlException
• QueryException
• ListException
• SObjectException
• LimitException
  
  • raised when our code exceeds a governor limit
  • the LimitException is the only standard exception that cannot be caught and handled

Question 2

How do you create a Custom Exception?

Answer 2

• we can create custom exceptions by making Apex classes with names that end in Exception and they extend the Exception class

public class FieldSecurityException extends Exception {}

Question 3

How do you throw a custom exception?

Answer 3

• we can throw custom exceptions by using the throw keyword and instantiating our Apex class that represents our custom exception

throw new FieldSecurityException(‘bleep.’);

Question 4

Explain Try-Catch-Finally Blocks

Answer 4

they handle our exceptions

• try
  
  • will surround the code that may throw an exception
• catch
  
  • follows the try block
  • we can have one or more catch blocks
  • handles the exception thrown by the code in the try block
• finally
  
  • follows the try block (and the catch block, if one is included)
  • will execute whether the code in the try block raised exception or not
• try blocks cannot be alone - they must have at least one catch or finally block following them

Question 5

Why do all exceptions (both standard and custom) have access to the Exception class methods?

Answer 5

• because all exceptions (both standard and custom) extend the Exception class, they inherit that class’s methods

Question 6

What are some exception class methods?

Answer 6

• getLineNumber() - returns code line exception was thrown at
• getMessage() - returns exception message
• getStackTraceString() - returns stack trace
• getTypeName() - returns type of exception