How to parse project properties or how to parse files with key-value pair

If a file has content like

app.enabled = false
app.host = "localhost"
app.port = 8080
app.zoneId = "zone_id"
app.fulOpId = "test_uk_1"

which are all key-value pairs, we could use properties.load() to parse it.

    public static Properties loadProperties() {
        Properties properties = new Properties();
        try {
            InputStream in = Thread.currentThread().getContextClassLoader().getResourceAsStream("project.properties");
            if(in==null) {
                logger.warn("The project.properties file does not exist");
            } else {
                properties.load(in);
            }
        } catch(Exception e) {
            logger.error("Unable to read the project.properties", e);
        }
        return properties;
    }

The reason to use Thread.currentThread().getContextClassLoader().getResourceAsStream("project.properties") and why it is different from normal class loader:

Each class will use its own classloader to load other classes. So if ClassA.class references ClassB.class then ClassB needs to be on the classpath of the classloader of ClassA, or its parents.

The thread context classloader is the current classloader for the current thread. An object can be created from a class in ClassLoaderC and then passed to a thread owned by ClassLoaderD. In this case the object needs to use Thread.currentThread().getContextClassLoader() directly if it wants to load resources that are not available on its own classloader.