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Tip of the Day
Language: Java
Expertise: Intermediate
Apr 19, 2007

Organizing and Loading Common/Specific Properties

Oftentimes, you'll need to use common properties across projects, while being able to override or load new properties that are project specific. Java's Properties class allows for flexibility when organizing this.

Suppose your common properties are in a file called common.properties, and two projects, A and B, have their properties in projectA.properties and projectB.properties:

import java.util.Properties;

// load common once
Common properties (in some shared/GlobalData class):
Properties commonProperties = new Properties(); 
commonProperties.load( this.getClass().getClassLoader().getResourceAsStream( "common.properties" );
In Project A's specific class:

Properties projectAProperties = new Properties( commonProperties );
projectAProperties.load( this.getClass().getClassLoader().getResourceAsStream( "projectA.properties" );
In Project B's specific class:

Properties projectBProperties = new Properties( commonProperties );
projectBProperties.load( this.getClass().getClassLoader().getResourceAsStream( "projectB.properties" );
Here are some suggestions for use:
  • Keep singletons containing common and specific properties.
  • Add initialize() methods that allow you to reload properties.
  • Name properties and files intuitively and organize them consistently.
  • Do not make these singletons depend on complex data or data loading mechanisms.
Rakesh Goenka
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