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The Java Developers Almanac 1.4Order this book from Amazon. |
e425. Applying Regular Expressions on the Contents of a FileThe matching routines injava.util.regex require that the input be a
CharSequence object. This example implements a method that
efficiently returns the contents of a file in a CharSequence object.
// Converts the contents of a file into a CharSequence // suitable for use by the regex package. public CharSequence fromFile(String filename) throws IOException { FileInputStream fis = new FileInputStream(filename); FileChannel fc = fis.getChannel(); // Create a read-only CharBuffer on the file ByteBuffer bbuf = fc.map(FileChannel.MapMode.READ_ONLY, 0, (int)fc.size()); CharBuffer cbuf = Charset.forName("8859_1").newDecoder().decode(bbuf); return cbuf; }Here is sample code that uses the method: try { // Create matcher on file Pattern pattern = Pattern.compile("pattern"); Matcher matcher = pattern.matcher(fromFile("infile.txt")); // Find all matches while (matcher.find()) { // Get the matching string String match = matcher.group(); } } catch (IOException e) { }
e424. Determining If a String Matches a Pattern Exactly e426. Removing Duplicate Whitespace in a String e427. Greedy and Nongreedy Matching in a Regular Expression e428. Escaping Special Characters in a Pattern
© 2002 Addison-Wesley. |