Java Properties File: How to Read Configuration Properties

A Properties file in Java is a simple text file used to store configuration data in the form of key-value pairs. This allows you to separate configuration from code, making your application more flexible and easier to maintain.

Properties File Format

The properties file contains entries like key=value. For example:

Properties file में entries इस तरह होती हैं: key=value. उदाहरण के लिए:

app.name=My Java App
app.version=1.0
db.user=root
db.password=admin123

Save this as config.properties file in your project folder.

इसे config.properties नाम से अपने project folder में save करें।

Java Code to Read Properties File

The following Java code uses the Properties class to load the config.properties file and read values by key.

नीचे दिया गया Java code Properties class का उपयोग करके config.properties file को load करता है और key के आधार पर values पढ़ता है।

import java.io.FileReader;
import java.io.IOException;
import java.util.Properties;

public class ReadProperties {
  public static void main(String[] args) {
    try {
      // Create a Properties object
      Properties props = new Properties();

      // Load properties file
      FileReader reader = new FileReader("config.properties");
      props.load(reader);

      // Read values by key
      String appName = props.getProperty("app.name");
      String version = props.getProperty("app.version");
      String user = props.getProperty("db.user");
      String password = props.getProperty("db.password");

      // Print values
      System.out.println("App Name: " + appName);
      System.out.println("Version: " + version);
      System.out.println("User: " + user);
      System.out.println("Password: " + password);

    } catch (IOException e) {
      System.out.println("Error reading file.");
      e.printStackTrace();
    }
  }
}

Output

App Name: My Java App
Version: 1.0
User: root
Password: admin123

Final Tips for Using Properties Files

Properties files help separate configuration from code, improving maintainability.
Use meaningful keys for better readability (e.g., app.name, db.user).
Always handle exceptions while reading the file to avoid runtime errors.
Protect sensitive data such as passwords; consider encrypting or securing the properties file.