In Java, the length() method of the String class returns the number of characters in a string, including spaces and special characters. The syntax is:
This method is useful for validating input, looping through characters, or checking if a string is empty (str.length() == 0). Unlike arrays, length() for strings is a method, not a property (array.length vs. string.length()).
If the string is null, calling length() throws a NullPointerException, so always check for null before using it.