Java 11 String isBlank() Method - Check Blank or Empty String in Java

Java isBlank() method is a String class method added into Java 11 version. This method is used to test a string whether it is empty or contains only whitespaces codepoints.

It returns either true or false. If the string is empty or contains whitespaces, it returns true, otherwise false.

Syntax

public boolean isBlank()

It does not take any argument.

Java 11 String isBlank Method Example

Lets have an example to understand this method. Here we are using empty string to check whether it is blank or not. Since it returns true for empty string, so here it does the same.


class Demo{
	public static void main(String[] args) {
		
		// empty string
		String str = " ";
		// isBlank
		boolean result = str.isBlank();
		System.out.println(result);
		
	}
}

Output:

true

Example: Whitespace codepoints

In this example, we are using some whitespace codepoints like: new line, tab etc to check whether the isBlank() method returns true or not. See the below example.

class Demo{
	public static void main(String[] args) {
		
		// newline 
		String str = "\n";
		// tab
		String str2 = "\t";
		// carriage return
		String str3 = "\r";
		// isBlank
		boolean result = str.isBlank();
		System.out.println(result);
		result = str2.isBlank();
		System.out.println(result);
		result = str3.isBlank();
		System.out.println(result);
		
	}
}

Output:

true

Example: Non Empty String

It returns false if string is non empty whether it includes spaces or not. See the below example.

class Demo{
	public static void main(String[] args) {
		
		// non empty string 
		String str = "hello";
		// string with spaces
		String str2 = "hello  ";
		// carriage return
		String str3 = "  hello  ";
		// isBlank
		boolean result = str.isBlank();
		System.out.println(result);
		result = str2.isBlank();
		System.out.println(result);
		result = str3.isBlank();
		System.out.println(result);
		
	}
}

Output:

false
false
false

Whitespace Codepoints

List of whitespace codepoints that are considered as blank by the String isBlank method.

'\t' - TAB CHARACTER
'\n' - NEW LINE CHARACTER
'\u' - VERTICAL TABULATION
'\f' - FORM FEED CHARACTER
'\r' - CARRIAGE RETURN CHARACTER

Java Character class has a method isWhitespace() to check whether a character is a whitespace or not. We can use it to ensure the charater is a whitespace codepoint. See the below example.

Example

class Demo{
	public static void main(String[] args) {
		
		String str = "\n";
		// is whitespace char
		boolean result = Character.isWhitespace('\n');
		System.out.println("Is empty: "+result);
		// isBlank
		result = str.isBlank();
		System.out.println("Is blank: "+result);
				
	}
}

Output:

Is empty: true
Is blank: true

Conclusion

Well, in this topic, we learnt about the new isBlank() method of String class. We go through the whitespace codepoins that are special characters and saw the behaviour of isBlank() method including use of iswhitespace() method.

If we missed something, you can suggest us at - info.javaexercise.com