Lessons

The fourth level is just beginning. You've probably not already lost your motivation, but why not give it another boost? Here are a couple of branches for the fire. In this article, our super specialist tells us why it's not easy to improve, and what to do about it. Hint: you need to chart your own course. The details are in the lesson.

It's time to dig deeper and understand what variables exist only at the level of a command, which exist until a method returns, and which exist as long as an object is alive. In this lesson, we'll try to understand the access modifiers "public" and "private". And let's also take a first look the special independent variables we call static.

There are no completely invisible variables. That would be pointless! But one may be visible throughout an entire object. Another may only be visible in a loop or another block. This approach may seem complicated, but it's actual completely logical. The same thing is true in life: homes aren't visible over a mountain, and from the street you can't see someone sitting at a computer and completing tasks about the visibility of variables.

On the fourth level, CodeGym students already know that in Java a code block is bounded on each side by curly brackets, and that each command ends with a semicolon... Or don't they know that yet? Or do they not know it, but instead intuitively feel it? In any case, it's time to deal with these concepts—the command and the code block.

Without conditional statements, a programmer must move straight ahead and never turn around. This is uninteresting and inefficient. So on the fourth level, it's time to teach branching. This will let us write smarter programs that can make choices. At least, like this: If (a == “right?”) {“sing song”} else if (a == “left?”) {“tell story”}.

In this lesson, CodeGym students familiar with the Pascal programming language will be able to enjoy a comparison between conditional operators in Java and those in this ancient but glorified language. And students who saw Pascal for the first time in one of the recent lessons will be able to work on becoming a polyglot.

We're not absolute. To realize our place in the world, we must compare ourselves with others... Uh, wait, why are we slipping into philosophy? In Java, mathematical comparisons are performed in the most ordinary way. In this lesson, we'll delve into comparison operators. We'll use them to create conditional statements and complete some interesting tasks to reinforce what you learn.

Remember the game "Truth or Lie"? Oh, wait. The game is called "Truth or Dare". "Truth or Lie" is the critical question for all logical tasks. This boils down to the fact that Java has a special type that can take only 2 values. You guessed correctly. These 2 values are true and false.

What if you need to repeat the same action several times as long as a certain condition is true? For example, here's a condition: "I will study at the secret CodeGym center while my level is <= 40". Or "while there is at least one cookie in the bag, eat it". The loop will stop only when the bag is empty. The Java while loop makes for an interesting lesson.

We continue our comparison of Java code and code written in Pascal—the academic superhit of all times and for all people, and the offspring of earthly scientist Nicklaus Wirth. Pascal is distinguished by its clear structure. Though not the shortest, code written in Pascal is very understandable. In ancient times, this is why students, and especially their teachers, fell in love with the language.

When you know loops, solving programming problems is easier, more interesting, and more natural! In fact, loops (repeated actions) form the basis of any automation and are the essence of programming. That's what Mark Zuckerberg thinks. Why not listen to him and master this important tool? In this lesson, we'll complete tasks using the while loop.

The nature of a loop is in its very name: repetition. In Java, there are several constructs for loops. Each of them is useful. In this lesson, we'll talk about the for loop. Programmers love and respect it for its compactness, convenience and...beauty, I guess. This loop is able to change code. See for yourself!