Regular Expression Syntax:
Here is the table listing down all the regular expression metacharacter syntax available in Java:
| Subexpression | Matches |
|---|---|
| ^ | Matches beginning of line. |
| $ | Matches end of line. |
| . | Matches any single character except newline. Using m option allows it to match newline as well. |
| [...] | Matches any single character in brackets. |
| [^...] | Matches any single character not in brackets |
| \A | Beginning of entire string |
| \z | End of entire string |
| \Z | End of entire string except allowable final line terminator. |
| re* | Matches 0 or more occurrences of preceding expression. |
| re+ | Matches 1 or more of the previous thing |
| re? | Matches 0 or 1 occurrence of preceding expression. |
| re{ n} | Matches exactly n number of occurrences of preceding expression. |
| re{ n,} | Matches n or more occurrences of preceding expression. |
| re{ n, m} | Matches at least n and at most m occurrences of preceding expression. |
| a| b | Matches either a or b. |
| (re) | Groups regular expressions and remembers matched text. |
| (?: re) | Groups regular expressions without remembering matched text. |
| (?> re) | Matches independent pattern without backtracking. |
| \w | Matches word characters. |
| \W | Matches nonword characters. |
| \s | Matches whitespace. Equivalent to [\t\n\r\f]. |
| \S | Matches nonwhitespace. |
| \d | Matches digits. Equivalent to [0-9]. |
| \D | Matches nondigits. |
| \A | Matches beginning of string. |
| \Z | Matches end of string. If a newline exists, it matches just before newline. |
| \z | Matches end of string. |
| \G | Matches point where last match finished. |
| \n | Back-reference to capture group number "n" |
| \b | Matches word boundaries when outside brackets. Matches backspace (0x08) when inside brackets. |
| \B | Matches nonword boundaries. |
| \n, \t, etc. | Matches newlines, carriage returns, tabs, etc. |
| \Q | Escape (quote) all characters up to \E |
| \E | Ends quoting begun with \Q |
Methods of the Matcher Class:
Here is the lists of useful instance methods:
Index Methods:
Index methods provide useful index values that show precisely where the match was found in the input string:
| SN | Methods with Description |
|---|---|
| 1 | public int start() Returns the start index of the previous match. |
| 2 | public int start(int group) Returns the start index of the subsequence captured by the given group during the previous match operation. |
| 3 | public int end() Returns the offset after the last character matched. |
| 4 | public int end(int group) Returns the offset after the last character of the subsequence captured by the given group during the previous match operation. |
Study Methods:
Study methods review the input string and return a boolean indicating whether or not the pattern is found:
| SN | Methods with Description |
|---|---|
| 1 | public boolean lookingAt() Attempts to match the input sequence, starting at the beginning of the region, against the pattern. |
| 2 | public boolean find() Attempts to find the next subsequence of the input sequence that matches the pattern. |
| 3 | public boolean find(int start Resets this matcher and then attempts to find the next subsequence of the input sequence that matches the pattern, starting at the specified index. |
| 4 | public boolean matches() Attempts to match the entire region against the pattern. |
Replacement Methods:
Replacement methods are useful methods for replacing text in an input string:
| SN | Methods with Description |
|---|---|
| 1 | public Matcher appendReplacement(StringBuffer sb, String replacement) Implements a non-terminal append-and-replace step. |
| 2 | public StringBuffer appendTail(StringBuffer sb) Implements a terminal append-and-replace step. |
| 3 | public String replaceAll(String replacement) Replaces every subsequence of the input sequence that matches the pattern with the given replacement string. |
| 4 | public String replaceFirst(String replacement) Replaces the first subsequence of the input sequence that matches the pattern with the given replacement string. |
| 5 | public static String quoteReplacement(String s) Returns a literal replacement String for the specified String. This method produces a String that will work as a literal replacement s in the appendReplacement method of the Matcher class. |
참조 : http://www.tutorialspoint.com/java/java_regular_expressions.htm
http://www.tuning-java.com/80
http://www.java2go.net/java/java_regex.html
http://www.java2s.com/Code/Java/Regular-Expressions/Stringreplace.htm