![]() replaceAll("", ""), which will replace anything with empty String except a to z, A to Z, 0 to 9,_ and dash. Similarly, if you String contains many special characters, you can remove all of them by just picking alphanumeric characters e.g. "Awesome!!!" and you want to remove those !!! to reduce some excitement, you can use replaceAll("!", "") to get rid of all exclamation marks from String. For example, suppose, your String contains some special characters e.g. Once you define that you can use a regular expression to replace those characters with empty String, which is equivalent to removing all special characters from String. Precisely, you need to define what is a special character for you. A special character is nothing but characters like - ! #, %, etc. Import can use a regular expression and replaceAll() method of class to remove all special characters from String. Package com.w3spoint import import public class RegexTest Let us discuss these with the below example. We can write a regular expression in 3 ways. Matches newlines, carriage returns, tabs, etc. ![]() ![]() Matches the backspace (0x08) when inside the brackets. Matches the word boundaries when outside the brackets. Matches the point where the last match finished.īack-reference to capture group number “n”. If a newline exists, it matches just before newline. Matches the independent pattern without backtracking. Groups regular expressions without remembering the matched text. Groups regular expressions and remembers the matched text. Matches at least n and at most m occurrences of the preceding expression. Matches n or more occurrences of the preceding expression. Matches exactly n number of occurrences of the preceding expression. Matches 0 or 1 occurrence of the preceding expression. Matches 0 or more occurrences of the preceding expression. Matches any single character not in brackets.Įnd of the entire string except allowable final line terminator. Matches any single character in brackets. Using m option allows it to match the newline as well. Matches any single character except newline. ![]() PatternSynta圎xception class object represents an unchecked exception that refers to a syntax error in a regular expression pattern. It returns the total number of the matched subsequence. It returns the ending index of the matched subsequence. It returns the starting index of the matched subsequence. It finds the next expression that matches the pattern from the given start number. It finds the next expression that matches the pattern. It test whether the regular expression matches the pattern. Matcher class object is the regex engine and used to perform match operations on a character sequence. It splits the given input string around matches of given pattern. It compiles the regular expression and matches the given input with the pattern. It works as the combination of compile and matcher methods. Static boolean matches(String regex, CharSequence input) It creates a matcher that matches the given input with pattern. It compiles the given regex and return the instance of pattern. A pattern class object represents a compiled version of a regular expression. Pattern class is used to define a pattern for the regex. The package primarily consists of the following 1 interface and 3 classes:
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