Java Regular expression matching slash

To match a slash inside a regular expression, you need to use 4 slashes:

Java code

Import Java.util.regex.Matcher;
Import Java.util.regex.Pattern;


public class Test {

	/**
	 * @param args */public
	static void Main (string[] args) {
		//TODO Auto-generat Ed method stub
		String textstring = new String ("\\\");
		
		Pattern Pt=pattern.compile ("\\\\\");
		
		Matcher Mc=pt.matcher (textstring);
		
	         Mc.replaceall ("xx");
		
		Textstring.replaceall ("\", "XX");
		
		String Bl=mc.replaceall ("xx");
		
		System.out.println (textstring);
		System.out.println (BL);
		}

Analyze "\\\\", the first slash is the escape character, the second slash is the slash itself, the third slash is an escape character, the fourth slash is the slash itself.

There are 2 points to be clear:

1. The string inside means that the slash requires two slashes such as "\"

2. The slash in the regular expression needs to turn, is marked with "\".

This is a better explanation:

Let's first represent the slash "\" inside the regular expression, and then the string representation. These 2 slashes require an escape character, which in turn represents a slash in the regular expression of 4 slashes.