java regex pattern matcher group example

Java Regex Pattern Matcher Group Example Full Article You
Java Regex Pattern Matcher Group Example Code Validator Which

Pattern and Matcher class and some cool methods provided by these classes.

PRANJAL AGNIHOTRI Jul 12, 2017 5 min read Regex is common in all language so discussion here gives you a idea about regex.

What is Regex Regex are Regular Expressions, very handy and powerful tool.

Java Regex Pattern Matcher Group Example Full Article You

Let me give you an example There are thousands of a r ticles on Medium and all have text format, now you were lazy and dont want to read the full article you just want to read some specific things in the article here you can use REGEX the specific things was your pattern and target text was your article Some very useful and helpful tools There are tons of visual regex tester but we will be using this.

Visual Regex tester shows you how your result will look like.Lets take a look So this is your tester there are two important fields target text and other is your Regular Expression (i.e.

Go and play with it very simple.

In the above example i wanted to get the numeric character from the text so i used d the regex for numeric character.

How to write Regular Expressions It needs lot of practice to get familiar to all the regular expression, while you dont need to memorize most of the time all refer to the nice short documentation here.

Once you will get used to it feels so good.So lets get started writing few.

Java Regex Pattern Matcher Group Example Code Validator Which

Lets start with an example We are making a postal code validator which will validate all postal codes which are of India.

Lets first visualize it in tester This was the result:) Hold on and we will get to it.First of all, the postal codes of India are of 6 digits so we have to accept only 6 digits and the character should be number.

Now take a look at my regex d6 here d means I am talking about numbers,now I have added a quantifier and have specified it should only accept 6 digits.

Accepted the zip-code which is to be validated in an string format.

Strings have that matches function which I used and passed my regex there as a string.

Now take a look at my regex which I have passed as a String in matcher().I have used here d because d means escape sequence in Java so using two backslash like d it tells that I am talking about actual d.

Even I was not, it comes by using it the more you use eventually you will get better just dont leave it until you r comfortable with it.

Lets take a look at one more example, Suppose we have to parse a cover letter of job aplicant and we are looking for a guy who is comfortable in HTML, CSS and Javascript First taking a look at visual tester.

Here the OR() operator is introduced which means one or more.

You can see in the regex something like (i) which means ignore the case in any case it will match and b here means the word boundary.

Before heading towards the code I will recommend you to see this documentation.

Java has its own class for Regex, I have used two subclasses Pattern and Matcher which ill be explaining.

Pattern is a class which takes your pattern which you r looking for in the target text.Pattern has static method compile which is the place where you have to pass your regex as I have did.

Matcher is nice little helper class which keeps track of what was matched.It has a find() method which keep track of what was matched and also shifts the internal state to next word which is to be matched.I have also used group method it groups up your matched text to produce result.