One of the features that make Java so powerful, is its object-oriented structure. This means that Java uses classes and objects to create more scalable, modular, and organized code.

Java's default constructor allows developers to create instances of classes when no other constructors are explicitly defined. The default constructor in Java takes no arguments -- it simply ...

Sealed classes in Java let developers limit the creation and use of subclasses and preserve the class hierarchy. Here is how sealed classes in Java work.

In Java, a package can contain other packages, classes, or both. When modeling, you’ll typically have logical packages that serve primarily to organize your model.

You must create a timer class instance to use the timer's functions. Add the following code to the Java file:timer = new Timer (countdown, this);Notice the "countdown" variable is used.