How to replace multiple spaces in a string using a single space using Java regex?

The metacharacter “\\s” matches spaces and + indicates the occurrence of the spaces one or more times, therefore, the regular expression \\S+ matches all the space characters (single or multiple). Therefore, to replace multiple spaces with a single space.

Match the input string with the above regular expression and replace the results with single space “ ”.

Example 1

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class ReplaceAllExample {
   public static void main(String args[]) {
      //Reading String from user
      System.out.println("Enter a String");
      Scanner sc = new Scanner(System.in);
      String input = sc.nextLine();
      String regex = "\\s+";
      //Compiling the regular expression
      Pattern pattern = Pattern.compile(regex);
      //Retrieving the matcher object
      Matcher matcher = pattern.matcher(input);
      //Replacing all space characters with single space
      String result = matcher.replaceAll(" ");
      System.out.print("Text after removing unwanted spaces: \n"+result);
   }
}

Output

Enter a String
hello this is a sample text with irregular spaces
Text after removing unwanted spaces:
hello this is a sample text with irregular spaces

Example 2

import java.util.Scanner;
public class Test {
   public static void main(String args[]) {
      //Reading String from user
      System.out.println("Enter a String");
      Scanner sc = new Scanner(System.in);
      String input = sc.nextLine();
      //Regular expression to match space(s)
      String regex = "\\s+";
      //Replacing the pattern with single space
      String result = input.replaceAll(regex, " ");
      System.out.print("Text after removing unwanted spaces: \n"+result);
   }
}

Output

Enter a String
hello this is a sample text with irregular spaces
Text after removing unwanted spaces:
hello this is a sample text with irregular spaces