regexp "-" in java code example

Example 1: java regex

import java.util.regex.*;  
public class RegexExample1{  
public static void main(String args[]){  
//1st way  
Pattern p = Pattern.compile(".s");//. represents single character  
Matcher m = p.matcher("as");  
boolean b = m.matches();  
  
//2nd way  
boolean b2=Pattern.compile(".s").matcher("as").matches();  
  
//3rd way  
boolean b3 = Pattern.matches(".s", "as");  
  
System.out.println(b+" "+b2+" "+b3);  
}}

Example 2: ("\\s","")regex java

x.replaceAll("\\s+", "");