Open In App

Java String isBlank() Method

Last Updated : 09 Dec, 2024
Summarize
Comments
Improve
Suggest changes
Share
Like Article
Like
Report

The String.isBlank() method is introduced in Java 11 and it checks if a string is empty or contains only whitespace characters (such as spaces, tabs, or newlines). This method simplifies string validation.

Example 1: In this example, we will use the basic approach to check if a given string is blank (empty or contains only whitespace) using isBlank() method.

Java
// Java program to demonstrate isBlank() method
public class StringIsBlank {
  
    public static void main(String[] args) {
      
        // Declare and initialize strings
        String s1 = "   ";    // String with only spaces
        String s2 = "Hello, World!";    // Non-empty string

        // Check if the strings are blank
        System.out.println(s1.isBlank());  
        System.out.println(s2.isBlank());  
    }
}

Output
true
false

Syntax of isBlank() Method

boolean isBlank()

Return Type:

  • Returns true, if the string is empty or only contains whitespace characters.
  • Returns false, if the string contains non-whitespace characters.

Example 2: This example demonstrates how to distinguish between an empty string ("") and a string that contains only whitespace characters.

Java
// Java program to distinguish between 
// empty and blank strings
public class StringIsBlank {
    public static void main(String[] args) {
      
        // Array of strings
        String[] s = {"", "   ", "Hello", " \t\n"};  

        // Loop through the array of strings
        for (int i = 0; i < s.length; i++) {
          
            // Check if the string is blank
            if (s[i].isBlank()) {
              
                System.out.println("String at index " + i 
                                   + " is blank (contains only whitespace).");
            } else {
                System.out.println("String at index " + i 
                                   + " is not blank.");
            }
        }
    }
}

Output
String at index 0 is blank (contains only whitespace).
String at index 1 is blank (contains only whitespace).
String at index 2 is not blank.
String at index 3 is blank (contains only whitespace).

Example 3: This example shows how to use isBlank() with conditional logic to handle blank inputs in an application.

Java
// Java program to use isBlank() with conditional logic
public class StringIsBlank {
    public static void main(String[] args) {
      
        // String with spaces
        String s = "   ";  

        // Check if the message is blank
        if (s.isBlank()) {

            System.out.println("The message is blank.");
        } else {
            System.out.println("Message: " + s);
        }
    }
}

Output
The message is blank.

Comparing isBlank() with Other Methods

Before Java 11, developers often used isEmpty() or a combination of trim() and isEmpty() to check for blank strings. However, isBlank() provides a simpler and more efficient solution, as it automatically handles both empty and whitespace-only strings in one call.

  • isEmpty(): Checks if the string length is 0, but does not account for strings that contain only whitespace.
  • trim().isEmpty(): Removes leading and trailing whitespace and then checks if the resulting string is empty.
  • isBlank(): Checks if the string is empty or consists only of whitespace.

Example:

Java
public class CompareMethods {
  
    public static void main(String[] args) {
      
        // Only whitespace
        String s = "   ";  

        // Using isEmpty
        System.out.println(s.isEmpty()); 

        // Using trim() + isEmpty
        System.out.println(s.trim().isEmpty());  

        // Using isBlank
        System.out.println(s.isBlank());  
    }
}

Output
false
true
true

Article Tags :
Practice Tags :

Similar Reads