Lessons

The computer revolution that began at the end of the 20th century led to the creation of the Internet (web) in mid-90s. And this sparked an even greater revolution. The Internet's effect is comparable to that of industrialization. But the most interesting fact is that this process is still in its infancy. A new world

In this lesson, we'll focus on objects. Basically, interaction between objects is what gives a program life and motion. And a class is just a blueprint for an object. Or a drawing, if you like. A programmer can create his or her own classes, or can use others' classes, creating objects or calling methods on existing classes.

It's time to talk about how variables are arranged internally. If you hear something about "primitive" types of data, it doesn't mean they're any worse than others. The designation only indicates that they're not composites. That is, a primitive type does not consist of any other types. Primitive and complex types are stored in different ways in memory.

How do you like this line? Cat cat = new Cat(); At first, it's confusing: why are there cats and both sides, and why is it so complicated? In fact, this is the standard way to create an instance (object) of the Cat class, named cat. The keyword new signals that we are creating a new "cat". This lesson has the details about creating cats and other objects.

There are different kinds of variables, and you can create them in different ways. For example, you can first create a variable and then (someday!) put a value in it. And you can do all this in a single line. You'll also learn the difference between creating primitive variables and creating objects (i.e. composite variables).

This lesson teaches you about the important difference between primitive and composite variables. For example, primitive variables contain an actual, but all other variables contain the address of an object. An object and a reference to it are related approximately in the way a person and her home address are related. Accordingly, objects interact with each other using references, and not directly.

A robot's full name consists of the manufacturer's name, the model, and a personal identifier. What about the full name of a class? You'll learn how to name classes properly so they can be accessed from anywhere. After this lesson, the name java.io.FileInputStream fileInputStream will be as clear and simple as "Albert Einstein".

You need to get used to working with real types (or floating-point numbers) in Java. Of course, it may be difficult to immediately accept that given float f = 3/5, f is actually zero! It's also unclear how to get the fractional number we need. In fact, all these problems are solved. And quite simply.

Does time have direction or does it simply exist? The Date type doesn't answer this question. But it helps solve all sorts of interesting problems. For example, measure time intervals, store dates and times, and calculate how many milliseconds have passed since January 1, 1970 GMT.

In this level, you learned what primitive types Java has and how they are expanded and narrowed. We talked about objects and classes. What's more, we began to study what makes Java Java — the principles of object-oriented programming. Be patient a little longer: before you proceed to the next...

As you complete the intense seventh level, you need a proper rest. Relaxation experts say changing your routine is the best way to achieve this. Before tackling the tasks at the very end of the level, watch a teaser trailer for the epic House of Codes. You might not yet fully realize what power you possess in your tender Java-programmer fingers. :)