How to Remove Whitespaces from a String in Java




In this blog, we will learn how to remove whitespaces from a string in Java. This will be asked in the most of the interviews. This can be implemented in three different ways listed below:

  1. Convert String into character array and use for loop
  2. For loop with charAt() method
  3. Using replaceAll() method

Method 1:

Convert String into Character array and use for loop

In the below snippet we have done the following

  • Created a string and assigned it with some value (includes whitespaces)
  • Created a character array and converted the string into the array by using .toCharArray() method
  • Created another empty string to store the output string
  • By using char.length() method we’ve iterated for loop
  • Used a If statement with a condition that to store only the values which are of not a period(whitespace) type.
public class RemoveWhitespacesString {

	public static void main(String[] args) {
		
		String str = "Java is a programming language";
		char ch [] = str.toCharArray();
		String str2 = "";
		for(int i=0; i<ch.length; i++)
		{
			if(ch[i]!=' ')
			{
				str2 = str2 + ch[i];
			}
		}
		
		System.out.println(str2);
	}
}

Output:
-------
Javaisaprogramminglanguage

Method 2:

Convert String into Character array and use for loop with CharAt() method

In the below snippet we have done the following

  • Created a string and assigned it with some value (includes whitespaces)
  • Created a character array and converted the string into the array by using .toCharArray() method
  • Created another empty string to store the output string
  • By using char.length() method we’ve iterated for loop
  • Used a If statement with a condition that to store only the values which are of not a period(whitespace) type.
  • Stored all the values into output string using charAt() method
public class RemoveWhitespacesString {

	public static void main(String[] args) {
		
		String str = "Java is a programming language";
		char ch [] = str.toCharArray();	
		String str3="";
		for(int i=0; i<ch.length; i++)
		{
			if(ch[i]!=' ')
			{
				str3 = str3 + str.charAt(i);
			}
			
		}
		System.out.println(str3);
		
	}
	
}

Output:
-------
Javaisaprogramminglanguage



Method 3:

Using replaceAll() method:

In the below snippet, we have done the following:

  • Created a string and assigned it with some value (includes whitespaces)
  • Created another string to store the output value
  • Using replaceAll() method with a regular expression which is a built-in method of string class we stored the value into the output string
public class RemoveWhitespacesString {

	public static void main(String[] args) {
		
		String str = "Java is a programming language";
		String str4=str.replaceAll(" ", "");
		System.out.println(str4);
	}
	
}


Output:
-------
Javaisaprogramminglanguage


Please watch the Youtube video for better understanding.



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