Property files are common in testing, and are usually used for storing test environment data. There are various formats for property files, but they usually store data strings in key/value pairings. In order to read a property file in Java, there is a class called Properties, which has various methods that load, list, set, or get properties. Here is an example of a property file pairing, with a method to read it, for storing Selenium driver properties:

# selenium.properties file

# driver revisions
selenium.revision=3.4.0
chrome.revision=2.30
safari.revision=2.48.0
gecko.revision=0.18.0
ie.revision=3.4.0

# browser versions
firefox.browser.version=54.0
chrome.browser.version=59.0
ie.browser.version=11.0
safari.browser.version=10.0
edge.browser.version=15.15063
...

/**
 * File I/O Static Utility Class
 *
 * @author name
 *
 */
public class File_IO {
    /**
    * loadProps- method to load a Properties file
    * 
    * @param file - The file to load
    * @return Properties - The properties to retrieve
    * @throws Exception
    */
    public static Properties loadProps(String file) throws Exception {
        Properties props = new Properties();
        props.load(new FileInputStream(file));

        return props;
    }
    ...

// use of file I/O method loadProps
public static final String SELENIUM_PROPS = new File("../myPath/selenium.properties")
                                                     .getAbsolutePath();

Properties seProps = File_IO.loadProps(SELENIUM_PROPS);

// get properties to use
String seleniumRev = seProps.getProperty("selenium.revision"));
String firefoxVer = seProps.getProperty("firefox.browser.version"));