Apex Developer Guide

Apex Developer Guide
Getting Started with Apex
Writing Apex
Data Types and Variables
Control Flow Statements
Classes, Objects, and Interfaces
Classes
Interfaces
Keywords
Annotations
Classes and Casting
Differences Between Apex Classes and Java Classes
Class Definition Creation
Namespace Prefix
Using the System Namespace
Using the Schema Namespace
Namespace, Class, and Variable Name Precedence
Type Resolution and System Namespace for Types
Apex Code Versions
Lists of Custom Types and Sorting
Using Custom Types in Map Keys and Sets
Working with Data in Apex
Running Apex
Debugging, Testing, and Deploying Apex
Apex Language Reference
Appendices
Glossary
PDF

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Namespace Prefix

The Salesforce application supports the use of namespace prefixes. Namespace prefixes are used in managed Force.com AppExchange packages to differentiate custom object and field names from those in use by other organizations.

After a developer registers a globally unique namespace prefix and registers it with AppExchange registry, external references to custom object and field names in the developer's managed packages take on the following long format:

1namespace_prefix__obj_or_field_name__c

Because these fully-qualified names can be onerous to update in working SOQL statements, SOSL statements, and Apex once a class is marked as “managed,” Apex supports a default namespace for schema names. When looking at identifiers, the parser considers the namespace of the current object and then assumes that it is the namespace of all other objects and fields unless otherwise specified. Consequently, a stored class should refer to custom object and field names directly (using obj_or_field_name__c) for those objects that are defined within its same application namespace.

Only use namespace prefixes when referring to custom objects and fields in managed packages that have been installed to your organization from the AppExchange.

Tip

Using Namespaces When Invoking Package Methods

To invoke a method that is defined in a managed package, Apex allows fully-qualified identifiers of the form:

1namespace_prefix.class.method(args)