Properties

Java Properties files use KEY=VALUE or KEY:VALUE format; they are the traditional configuration format of the Java ecosystem and support Unicode escapes.

Purpose

To provide the standard Java configuration file format, used together with the Properties class.

Mechanism

Each line is KEY=VALUE or KEY:VALUE (either separator works), with # or ! comments. Non-ASCII characters are escaped as \uXXXX. No nesting (prefixes simulate namespaces). Loaded by java.util.Properties.

Use cases

Java application configuration
Spring Boot application.properties
Android resources
Legacy Java configuration

Examples

Input

db.url=jdbc:postgres://...

Output

Properties {db.url:...}

A key-value pair

Common errors

Mixing = and : as separators creates ambiguity: Standardize on = as the separator

Related terms

INI is a traditional configuration file format that groups settings with [section] headers and key=value pairs; it is simple but unstandardized, and implementations differ slightly.

An ENV file defines environment variables in KEY=VALUE format for application configuration; it is the recommended approach of 12-factor apps.

YAML (YAML Ain't Markup Language) is a configuration-oriented data serialization format using indentation for hierarchy, supporting comments and references, and better suited to hand editing than JSON.

Related tools

Properties To Json

Properties To Json — pure client-side tool. Privacy-first, no server round-trip.

Properties Parser

Parse Java .properties KEY=VALUE lines into JSON. Line continuation (a trailing backslash merging the next line) is not supported — the backslash stays in the value and the next line is read as a new entry. Lines starting with # or ; are treated as comments.

Properties Stringify

Properties Stringify — pure client-side tool. Privacy-first, no server round-trip.

References