Any word that contains numbers and letters is known as alphanumeric. The following regular expression matches the combination of numbers and letters."^[a-zA-Z0-9]+$";The matches method of the String class accepts a regular expression (in the form of a String) and matches it with the current string in case the match this ... Read More

The simple character class “[ ]” matches all the specified characters in it. The following expression matches the characters except for xyz."[xyz]"Similarly, the following expression matches all the vowels in the given input string."([^aeiouAEIOU0-9\W]+)";Then you can remove the matched characters by replacing them with the empty string “”, using the ... Read More

The simple character class “[ ]” matches all the specified characters in it. The meta character ^ acts as negation within the above character class i.e. the following expression matches all the characters except b (including spaces and special characters)"[^b]"Similarly, the following expression matches all the consonants in the given ... Read More

You can group all the required characters to match within the square braces “[ ]” i.e. The metacharacter/sub-expression “[ ]” matches all the specified characters. Therefore, to match all the letters specify the vowel letters within these as shown below −[aeiouAEIOU]Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class MatchVowels ... Read More

The subexpression “[ ]” matches all the characters specified in the braces. Therefore, to move all the upper case letters to the end of a string −Iterate through all the characters in the given string.Match all the upper case letters in the given string using the regular expression "[A-Z]".Concatenate the ... Read More

The following regular expression matches all the special characters i.e. all characters except English alphabet spaces and digits."[^a-zA-Z0-9\s+]"To move all the special characters to the end of the given line, match all the special characters using this regex concatenate them to an empty string and concatenate remaining characters to another ... Read More

The \b meta character in Java regular expressions matches the word boundaries Therefore to find a particular word from the given input text specify the required word within the word boundaries in the regular expressions as −"\brequired word\b";Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class MachingWordExample1 {    public ... Read More

The java.util.regex.Matcher class represents an engine that performs various match operations. There is no constructor for this class, you can create/obtain an object of this class using the matches() method of the class java.util.regex.Pattern.The usePattern() method of the Matcher class accepts a Pattern object representing a new regex pattern and ... Read More

The appendReplacement() method of the Matcher class accepts a StringBuffer object and a String (replacement string) as parameters and, appends the input data to the StringBuffer object, replacing the matched content with the replacement string.Internally, this method reads each character from the input string and appends the String buffer, whenever ... Read More

The java.util.regex.Matcher class represents an engine that performs various match operations. There is no constructor for this class, you can create/obtain an object of this class using the matches() method of the class java.util.regex.Pattern.The hitEnd() method verifies whether the end of the input data reached during the previous match if ... Read More