Hello, in this video we are going to cover regular expressions in Java, also known as reg x a regular expression is basically a way of checking for something and that indeed is impossible. Yeah, where you will need a important is not that one. Okay, so yeah, regular expression allows you to let's say, check the format of something or check if something, you know occurred in a sequence in a string, for example. So the input that we need to import Java dot util. Read and just put apostrophes with everything from there. That's it for the input side.

So what we'll do first of all, you put the pattern and we'll call this Pat equals pattern dot compile, compile and in here We're going to do a pattern. So it points to say just one character. And that's going to be the pattern. And so what we did was that and I said, The coteries? I do, because that's the letter of the first letter of my name. And no need to Chris Macha.

And I'll call this Matt. Pat, Matt. The names everywhere. Yes, we do path dot matcher. But this is one way of doing it exactly a few different ways of doing it. This is one way some pattern matcher and this is basically what you want to check for.

I mean, this is the stream that you want to check. So if I check for know, for hot, which is my name, and then Boolean 01 equals x Max dot matches and then if we do System dot out dot print line run go on run this little bad boy and they it seemed false Ah sorry my bad that is to do with why you matcha is not finding in there so let's have a look. So we pattern you know quoted Pat pattern up compile and we got change back to a lowercase r sorry I put the dot there so it means there will be something before it for putting on the line that What is happening today My mind is all over the place is extremely strange. Okay, there no why is not working? Ah, okay, so let's try with a lowercase f just to make sure.

Okay, so it is case sensitive symptoms got that and I forgot. Like, I'll come from another language where the regex can be like if you put something like say like a doctor or an aspirin just mean there's something before it, but this needs to specify the exact number of characters before or after. So you could you know, let's change that to an A still prints out true If I change this to the no G, so it's like a pawn. It does not work. Well, let's just change this back. So that's one way of doing it.

And another way of doing it is I'll do the second and third one to go. So you can see different ways to create another Boolean result of the match is successful or not. So for the result to equals and what you do pattern dot compile. And exactly the same thing as here and I'll copy just make sure I don't make a mistake. And then you do document Then the string I'm sure name correctly, I did first time, which is awesome. dot matches.

So this is basically the same thing as before, but it's all in line now. System dot out, dot print line. First method is great if you're going to be using sad things somewhere else. But this is great if it wants to be quick, easy, and you want to reduce the amount of code so both of them return true as rightfully they should. The other option, and this is a lot simpler and different, probably what you'll see more likely, Boolean results equals pattern match if you specify the actual format, so you know the regular expression, F dot, dot dot dot dot dot. Now use that for displaying.

We run it and printed it out. System dot out dot print line, result free. And if we run it, we get true as well. So this is the preferred method for most people. So what I want you to do as an extra task is write a bunch of extra regular expressions. It doesn't matter which method you use.

Properly. This underscore is easier and faster to do but like right over it different one we created before after characters in between uppercase and lowercase, maybe even those that server, check out the video that we did on console impo and get some input from the user and then check if it is valid. format. So that's it for regular expressions. You know, there's a lot more formatting that you can do, but this is the you know, the essence of it. What I will actually do is provide you with a link that shows you all the different facets of regular expressions in Java.

Feel free to check that out and do some more experimentation. And I look forward to seeing you in the next awesome Java video.