Understanding java-11.5 Scan Input (2)-scanner boundary and using regular expression scan

Source: Internet
Author: User

In this chapter we introduce the boundary of scanner and the use of regular expression scans.

Boundary of 1.scanner

In the previous chapter, we mentioned that there are hasnext methods in scanner, which can detect if there are strings, in fact, this is the boundary character, check the boundary of the string.

Package Com.ray.ch11;import Java.io.bufferedreader;import Java.io.ioexception;import java.io.stringreader;import Java.util.scanner;public class Test {private BufferedReader input = new BufferedReader (new StringReader ("raylee\n31\ n1.77 "));p ublic BufferedReader getinput () {return input;} public void SetInput (BufferedReader input) {this.input = input;} public static void Main (string[] args) throws IOException {test test = new Test (); Scanner Scanner = new Scanner (Test.getinput ()), while (Scanner.hasnext ()) {System.out.println (Scanner.nextline ());}}}

Output:

Raylee
31
1.77


2. Using regular expression scanning

A lot of time we need to scan and statistics log situation, and the general log is recorded in a TXT file, then this time the regular expression and scanner of the match is quite efficient, we look at the following code:

Package Com.ray.ch11;import Java.io.bufferedreader;import Java.io.ioexception;import java.io.stringreader;import Java.util.scanner;import Java.util.regex.matchresult;import Java.util.regex.pattern;public class Test {private BufferedReader input = new BufferedReader (New StringReader ("[email protected]@2015-12-01\n" + "[email  protected]@2015-12-03\n "+" [email protected]@2015-12-05\n "+" [email protected]@2015-12-07\n "+" end\n ")) ;p ublic BufferedReader getinput () {return input;} public void SetInput (BufferedReader input) {this.input = input;} public static void Main (string[] args) throws IOException {test test = new Test (); Scanner Scanner = new Scanner (Test.getinput ()); Pattern pattern = Pattern.compile ("(\\d+[.) \\d+[.] \\d+[.] \\d+) "+" @ "+" ([a-z]+) + "@" + "(\\d{4}-\\d{2}-\\d{2})"), while (Scanner.hasnext (pattern)) {Scanner.next (pattern); Matchresult Matchresult = Scanner.match (); System.out.println ("IP:" +matchresult.group (1)); System.out.println ("User:" +matchresult.group (2)); System.out.println ("Date:" +matchresult.group (3));}}}

Output:

ip:127.0.0.1
User:admin
Date:2015-12-01
ip:127.0.0.2
User:ray
date:2015-12-03
ip:127.0.0.31
User:rose
date:2015-12-05
ip:127.0.0.41
User:jack
date:2015-12-07


In the above code there is a very important place to note is the writing of regular expressions, especially a few parentheses, because the string can be grouped by a few parentheses. If there are no parentheses, the following group (1) Group (2) will throw an exception.


Summary: This chapter simply describes the boundary of the scanner and the use of regular expression scans.


This chapter is here, thank you.

-----------------------------------

Directory


Understanding java-11.5 Scan Input (2)-scanner boundary and using regular expression scan

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.