How to tell if a string contains only numbers and letters in java?

#How does Java determine if a string contains only numbers and letters?

In java, you can use regular expressions ("^[a-z0-9A-Z] $") to determine whether a string contains only numbers and letters.

Go directly to the code

public static boolean isLetterDigit(String str) {
  String regex = "^[a-z0-9A-Z]+$";
  return str.matches(regex);
 }

java regular expression

Regular expression defines the pattern of the string.

Regular expressions can be used to search, edit or process text.

Regular expressions are not limited to a certain language, but there are subtle differences in each language.

The following table lists some examples and descriptions of regular expressions:

Regular expressions	Description
this is text	Matches the string "this is text"
this\s is\s text	Note the \s in the string. Match the \s after the word "this" to match multiple spaces, then match the is string, and then \s match multiple spaces and then follow on text string. can match this instance: this is text
##^\d (\.\d )?	^ Defines what starts with \d Matches one or more digits ? Setting options within brackets is optional \. Matches " ." Matches examples: "5", "1.5" and "2.21".

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