In the Java programming language

Java (programming language)

Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...

 a resource is a piece of data that can be accessed by the code of an application

Application software

Application software, also known as an application or an "app", is computer software designed to help the user to perform specific tasks. Examples include enterprise software, accounting software, office suites, graphics software and media players. Many application programs deal principally with...

.
An application can access its resources through Uniform Resource Locator

Uniform Resource Locator

In computing, a uniform resource locator or universal resource locator is a specific character string that constitutes a reference to an Internet resource....

s, like web resources

Resource (Web)

The concept of resource is primitive in the Web architecture, and is used in the definition of its fundamental elements. The term was first introduced to refer to targets of Uniform Resource Locators , but its definition has been further extended to include the referent of any Uniform Resource...

, but the
resources are usually contained within the JAR

JAR (file format)

In software, JAR is an archive file format typically used to aggregate many Java class files and associated metadata and resources into one file to distribute application software or libraries on the Java platform.JAR files are built on the ZIP file format and have the .jar file extension...

 file(s) of the application.

A resource bundle

Java resource bundle

A resource bundle is a Java .properties file that contains locale-specific data. It is a way of internationalising a Java application by making the code locale-independent.- Benefits of using resource bundles :...

 is a set of key and value pairs, stored as a resource, that is commonly used to allow the localization of an application. For this purpose different resource bundles with a
common set of keys are used to store translations for the messages and user interface

User interface

The user interface, in the industrial design field of human–machine interaction, is the space where interaction between humans and machines occurs. The goal of interaction between a human and a machine at the user interface is effective operation and control of the machine, and feedback from the...

texts of an application.