The Java built-in java.util.Properties class could really use some love. I have written a slightly improved version called timemachine.scheduler.support.Props, and below are some features that I use often.

You can use it as a "String Map" of properties

    Props props1 = new Props();
    props1.put("foo", "bar");
    
    // It can load from/to the Java Properties
    Props props2 = new Props(System.getProperties());
    java.util.Properties javaProps = props3.toProperties();
    
    // It can load from/to a basic java.util.Map
    Props props3 = new Props(System.getenv());
    
    // Props is a HashMap<String, String>, so no need to convert. Just use it
    for(Map.Entry<String, String> entry : props3.entrySet())
        System.our.println(entry.getKey() + ": " + entry.getValue());

You can load from a file in a single line

    Props props1 = new Props("config.properties");
    Props props2 = new Props("/path/to/config.properties");
    Props props3 = new Props(new java.net.URL("http://myhost/config/config.properties"));
    Props props4 = new Props(ClasspathURLStreamHandler.createURL("classpath://config/config.properties"));
    
    // You can re-load on top of existing instance to override values
    props4.load("config2.properties");

NOTE: The ClasspathURLStreamHandler is a utility class from the same package under timemachine.scheduler.support that can load any resources that's in the classpath.

You can get many basic types conversion

    Props props = new Props();
    props.put("str", "foo");
    props.put("num", "123");
    props.put("dec", "99.99");
    props.put("flag", "true");
    
    String str = props.getString("str");
    int num = props.getInt("num");
    double dec = props.getDouble("dec");
    boolean flag = props.getBoolean("flag");
    
    // You can even get default value when key is not found too
    int num2 = props.getInt("num2", -1);

You can auto expand ${variable} from any existing properties

    Props props = new Props(System.getProperties());
    props.put("configDir", "${user.home}/myapp/config");
    props.expandVariables();
    
    // The ${user.home} should be expanded to actual user home dir value.
    File dir = new File(props.get("configDir"));

There you have it. You see more code than words in this post, but I believe simple code speak louder than words and docs. I find these features very convenient and practical for many Java applications to use. I wish the JDK would provide these out of the box, and make the java.util.Properties more developer friendly.