Java programs are made up of statements. Now, a lot of different things can go on in a statement, and we'll talk about those things throughout this course, but fundamentally, programs are made with statements. Now each statement ends with a semicolon. Java is a language where the newline and the Enter key doesn't really create a new statement. It relies instead on the semicolon. If you're going from any of the C‑based languages, that's something you're very familiar with. Other languages like Visual Basic use the end of line to mark a statement. In Java, it's the semicolon. And the parts of a statement can be separated by zero or more whitespaces, and a whitespace could be many different things. It can be the space character, it can be a tab. And because statements don't end with newline, even the newline itself is just a whitespace in Java. Java's a language that gives us a lot of flexibility with whitespaces, so remember we said that the parts could be separated by zero or more whitespaces, so it allows us to format things in a way that works well for us. So I can have a statement like this where all the parts are pushed all together with no whitespaces between them, but then I can have this same statement where I just put a space after the printing, a space after the parenthesis, a space before the other parenthesis. It'll do the exact same thing. I can put multiple spaces in there, and that still does the exact same thing. Now remember that because the newline is considered a whitespace, I can even format it like this. This is kind of a crazy way to format it, and I wouldn't suggest you do this, but it's all just whitespace. So, after that printing, we've got a newline, followed by a bunch of the space characters. That's fine. Right after that parenthesis, we've got a newline again. After Hello World, we've got a newline, another newline, then a whole bunch of whitespaces or a whole bunch of space characters. And so, it just shows us that the whitespace allows us to indent, format, put line breaks in a way that works well for us. The whitespaces are just separators, and it's that semicolon that marks the end of a statement.
In order to do anything interesting in a program, we must have the ability to store and manipulate values. What allows us to do that are what we call variables. Now a variable, simply put, is just named data storage. Now Java is a strongly ‑ typed language. Now what that means is that when we declare a variable like, in this case, we have a variable named data Value, we have to specify the type of that variable, in this case, it's what we call an int, something that can store integers. So, what that means is that the data Value variable can only store things that are compatible with the type int. As we go through the course, we'll talk about this idea of one type being compatible with another. Now when we declare a variable, we can, of course, then assign a value to it, so our variable data Value now holds the value 100. Now when we use variables, we can do it the way we've done here where we declare it, then assign it, or as a matter of convenience, we can declare them a...
Comments
Post a Comment
We appreciate your valuable Suggestions/Feedback