How to remove whitespaces from a string in Java

In this shot, we will discuss how to remove all whitespaces from a string in Java. Here, we will take a string from the user as input and then we will remove all the spaces from it.

Solution approach

We have two methods to remove all the whitespaces from the string.

  1. In Java, we can use the built-in replaceAll() method to remove all the whitespaces of the given string. In fact, we can replace any character of a string with another using this method.

  2. We can also remove whitespaces manually. To remove all the whitespaces, we have to traverse through the string once and append the characters other than whitespaces in a string buffer. Then, we convert that StringBuffer into a string using the built-in Java method toString().

Code

To understand this better let’s look at the below code snippet.

Input any text with whitespaces. For example: Educative is cool!

import java.util.Scanner;
class RemoveWhitespaces {
   public static void main(String[] args) {
       Scanner sc= new Scanner((System.in));
       System.out.println("Enter the input String:-");
       String input= sc.nextLine();
       String ans1= input.replaceAll("\\s","");
//replace all whitespaces with blank
       String ans2=removeSpaces(input);
       System.out.println("Desired string using method-1:\t"+ans1);
       System.out.println("Desired string using method-2:\t"+ans2);
   }
   static String removeSpaces(String str){
       StringBuffer st= new StringBuffer();
       for(char c:str.toCharArray()){
           if(c!=' ' && c!='\t'){
               st.append(c);
           }
       }
       return st.toString();
   }
}

Enter the input below

Explanation

  • In line 1, we imported the java.util.Scanner class to read input from the user.

  • In line 7, inside the main function, we took the input string from the user by creating a Scanner object and stored that input in a String input.

  • In line 8, we call the replaceAll() function, replace all the whitespaces with blank, and store the resultant string in the ans1 variable.

  • In line 9, we call the removeSpaces() method and pass the input string as a parameter to it. This method will return the string without whitespaces and store the resultant string in a variable ans2.

  • In lines 10 and 11, we print the output that we get by using method-1 and method-2 respectively to compare them.

  • In lines 13 to 21, we defined the removeSpaces() function. Inside the function, we initialized a variable st of StringBuffer type and we run a for loop for the given string. If any character other than white space is found then append it to st.

  • After ending the loop, we convert StringBuffer into a string using the toString() method and return it.

  • At the input/output section we can see we get the same output for both the methods.

In these ways, we can remove all whitespaces from a string in Java.

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