Java String isBlank() Method Examples

Java String isBlank() method returns true if the string is empty or contains only white spaces codepoints. This utility method was added to String class in Java 11 release.


White Space Unicode Code Points in Java

Java considers the following characters as white space. Note that this is not an extensive list and there are high chances that I might have missed some special white space Unicode characters.

  • \n or \u005Cn – newline character
  • \t or \u005ct – tab character
  • \r or \u005Cr – carriage return
  • \u005ct – horizontal tabulation
  • \u005Cn – line feed
  • \u000B – vertical tabulation
  • \u005Cf – form feed
  • \u001C – file separator
  • \u001D – group separator
  • \u001E – record separator
  • \u001F – unit separator

Java String isBlank() Examples

Let’s look at some examples of isBlank() method.

1. String is empty

jshell> String str = "";
str ==> ""

jshell> str.isBlank();
$32 ==> true

2. The string contains only tab, newline, carriage return characters

jshell> String str = " \t ";
str ==> " \t "

jshell> str.isBlank()
$34 ==> true

jshell> str = " \n\n\r ";
str ==> " \n\n\r "

jshell> str.isBlank()
$36 ==> true

3. The string contains special white space characters

jshell> char[] chars = { '\u005ct', '\u005Cn', '\u000B', '\u005Cf', '\u005Cr', '\u001C', '\u001D', '\u001E', '\u001F' };
chars ==> char[9] { '\t', '\n', '\013', '\f', '\r', '\034', '\035', '\036', '\037' }

jshell> String str = new String(chars);
str ==> "\t\n\013\f\r\034\035\036\037"

jshell> str.isBlank();
$39 ==> true
Java String IsBlank Example
Java String isBlank() Example – Special White Space Characters

4. The string contains non-white space characters

jshell> String str = "   H  ";
str ==> "   H  "

jshell> str.isBlank();
$41 ==> false

String isBlank() vs isEmpty()

  • String isBlank() is used to test if the string is empty or contains only white space characters.
  • String isEmpty() method is used to test if the string is empty or not.

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