Apex Developer Guide

Apex Developer Guide
Release Notes
Getting Started with Apex
Writing Apex
Data Types and Variables
Control Flow Statements
Classes, Objects, and Interfaces
Classes
Interfaces
Keywords
Annotations
Classes and Casting
Classes and Collections
Collection Casting
Differences Between Apex Classes and Java Classes
Class Definition Creation
Namespace Prefix
Apex Code Versions
Lists of Custom Types and Sorting
Using Custom Types in Map Keys and Sets
Working with Data in Apex
Document Your Apex Code
Running Apex
Debugging, Testing, and Deploying Apex
Apex Reference
Appendices
PDF

Note: This release is in preview. Features described here don’t become generally available until the latest general availability date that Salesforce announces for this release. Before then, and where features are noted as beta, pilot, or developer preview, we can’t guarantee general availability within any particular time frame or at all. Make your purchase decisions only on the basis of generally available products and features.

Classes and Casting

In general, all type information is available at run time. This means that Apex enables casting, that is, a data type of one class can be assigned to a data type of another class, but only if one class is a subclass of the other class. Use casting when you want to convert an object from one data type to another.

In the following example, CustomReport extends the class Report. Therefore, it is a subclass of that class. This means that you can use casting to assign objects with the parent data type (Report) to the objects of the subclass data type (CustomReport).

In the following code segment, a custom report object is first added to a list of report objects. Then the custom report object is returned as a report object, which is then cast back into a custom report object.

Casting Example A flowchart of the Apex casting process

In addition, an interface type can be cast to a sub-interface or a class type that implements that interface.

To verify if a class is a specific type of class, use the instanceOf keyword. For more information, see Using the instanceof Keyword.

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