StringUtils.isBlank()

The `StringUtils.isBlank()` method is a part of the Apache Commons Lang library that checks if a given string is null or empty (length of 0) or contains only white space characters. The method returns a boolean value `true` if the string meets any of these conditions and `false` otherwise. Here's an example:

import org.apache.commons.lang3.StringUtils;

public class StringUtilsExample {
    public static void main(String[] args) {
        String str1 = null;
        String str2 = "";
        String str3 = "   ";
        String str4 = "hello world";

        System.out.println(StringUtils.isBlank(str1)); // true
        System.out.println(StringUtils.isBlank(str2)); // true
        System.out.println(StringUtils.isBlank(str3)); // true
        System.out.println(StringUtils.isBlank(str4)); // false
    }
}