Class Validator
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Thread: Class Validator

  1. #1
    Join Date
    Dec 2011
    Posts
    1

    Class Validator

    I'm attempting to code a program that validates a file named as Class.txt, the contents of the file are: class test {
    int i;
    }

    the thing is, I can't get past the first two words, class and test. Can anyone help me?

    the code is as follows:

    import java.io.File;
    import java.io.FileReader;
    import java.io.IOException;

    public class Parser {

    private FileReader content;
    private int currentLineNumber = 1;
    private int currentCharNumber = 0;
    private int currentValue;
    private char currentChar;
    private String token;

    public static void main( String[] args ) {
    try {
    new Parser( new File( "C:/Class.txt" ) ).parse();
    } catch ( ParseException exc ) {
    exc.printStackTrace();
    } catch ( IOException exc ) {
    exc.printStackTrace();
    }
    }

    public Parser( File file ) throws IOException {
    content = new FileReader( file );
    }

    public void parse() throws ParseException, IOException {

    nextToken();

    if ( token.equals( "class" ) ) {
    System.out.println( token );
    nextToken();
    } else {
    throw new ParseException( token, currentLineNumber, currentCharNumber );
    }

    identifier();

    if ( token.equals( "{" ) ) {
    System.out.println( token );
    nextToken();
    } else {
    throw new ParseException( token, currentLineNumber, currentCharNumber );
    }

    type();
    identifier();

    if ( token.equals( "}" ) ) {
    System.out.println( token );
    nextToken();
    } else {
    throw new ParseException( token, currentLineNumber, currentCharNumber );
    }

    if ( token == null ) {
    System.out.println( "file syntactically correct." );
    }

    }

    private void type() throws ParseException, IOException {

    if ( token.equals( "int" ) || token.equals( "string" ) || token.equals( "char" ) ) {
    System.out.println( token );
    nextToken();
    } else {
    throw new ParseException( token, currentLineNumber, currentCharNumber );
    }

    }

    private void identifier() throws ParseException, IOException {

    if ( token.matches( "^[a-zA-Z]+[a-zA-Z0-9]*" ) ) {
    System.out.println( token );
    nextToken();
    } else {
    throw new ParseException( token, currentLineNumber, currentCharNumber );
    }

    }

    private void nextToken() throws IOException {

    token = null;

    while ( ( currentValue = content.read() ) != -1 ) {

    currentChar = (char) currentValue;

    if ( currentChar != ' ' && currentChar != '\n' && currentChar != ';' ) {
    if ( token != null ) {
    token += currentChar;
    } else {
    token = String.valueOf( currentChar );
    }
    currentCharNumber++;
    } else {
    if ( currentChar == ' ' ) {
    currentCharNumber++;
    break;
    } else if ( currentChar == '\n' ) {
    currentLineNumber++;
    currentCharNumber = 1;
    break;
    }
    }

    }

    }

    }

    public class ParseException extends Exception {

    private String token;
    private int line;
    private int Char;

    public ParseException( String token, int line, int Char ) {
    this.token = token;
    this.line = line;
    this.Char = Char;
    }

    @Override
    public String toString() {
    return String.format(
    "Error \"%s\" (line: %d, Char: %d)",
    token, line, Char );
    }

    }
    Attached Files Attached Files

  2. #2
    Join Date
    May 2006
    Location
    UK
    Posts
    4,473

    Re: Class Validator

    Have you considered using a Doclet in conjunction with the JavaDoc program. JavaDoc parses java files and exposes the constituent parts to the plugin Doclet.

    There are various on-line articles on writing Doclets such as this one
    Posting code? Use code tags like this: [code]...Your code here...[/code]
    Click here for examples of Java Code

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