String.startsWith() to detect more than one line and parse it into the same variable - Artificial Intelligence

fuschia
October 26, 2014
148 views
2 votes
3 Answers

Im trying to parse an input file as follows:

#*Nonmonotonic logic - context-dependent reasoning.
#@Victor W. Marek,Miroslaw Truszczynski
#t1993
#cArtificial Intelligence
#index3003478
#%3005567
#%3005568
#!abstracst

#*Wissensrepräsentation und Inferenz - eine grundlegende Einführung.
#@Wolfgang Bibel,Steffen Hölldobler,Torsten Schaub
#t1993
#cArtificial Intelligence
#index3005557
#%3005567
#!abstracts2

Im creating the parser for this file and Im looking for an output as follows:

Nonmonotonic logic - context-dependent reasoning.   Victor W. Marek,Miroslaw Truszczynski   1993    Artificial Intelligence 3003478 300557,300558  
Wissensrepr?sentation und Inferenz - eine grundlegende Einf?hrung.  Wolfgang Bibel,Steffen H?lldobler,Torsten Schaub    1993    Artificial Intelligence 3005557 3003478

However the line started with #% can be multiple and I could not figure out how to handle this. So the output is always double for the part with more than one #%. For example:

Nonmonotonic logic - context-dependent reasoning.   Victor W. Marek,Miroslaw Truszczynski   1993    Artificial Intelligence 3003478 300557
Nonmonotonic logic - context-dependent reasoning.   Victor W. Marek,Miroslaw Truszczynski   1993    Artificial Intelligence 3003478 300557  300558  
Wissensrepr?sentation und Inferenz - eine grundlegende Einf?hrung.  Wolfgang Bibel,Steffen H?lldobler,Torsten Schaub    1993    Artificial Intelligence 3005557 3003478

Below is my code. Before, I also tried to change my code’s last if condition that handle #% into while but it was not working as well.
Im thinking about detecting if the next line after the line starts with #% is also started with #% then it should be parsed into the same variable. However, I could not figure out the right syntax to do this. I triend hasNext() and next() but it had a syntax error in my java program. Im not really strong in programming so I asked for help here..

import java.util.Scanner;
import java.io.*;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.file.Path;
import java.nio.file.Paths;

public class Citation2{

    String title;
    String author;
    String year;
    String conference;
    String index;
    String cite;
    String abstracts;
    String Line;

    public static void main (String[] args) throws SQLException,
    ClassNotFoundException, IOException{

        Citation2 parser = new Citation2("D:/test.txt");
        parser.processLineByLine();

    }

     public Citation2(String aFileName){
         fFilePath = Paths.get(aFileName);
     }

     public final void processLineByLine() throws IOException, ClassNotFoundException, SQLException {
         try (Scanner scanner =  new Scanner(fFilePath, ENCODING.name())){
              while (scanner.hasNextLine()){
                  processLine(scanner.nextLine());
              }      
            }
     }

     protected void processLine(String aLine) throws ClassNotFoundException, SQLException {


                if (aLine.startsWith("#*")) {
                      title = aLine.substring(2);
                      Line = title;
                } 
                else if (aLine.startsWith("#@")){
                       author = aLine.substring(2);
                       Line = Line + "t" + author;
                }
                else if (aLine.startsWith("#t")){
                       year = aLine.substring(2);
                       Line = Line + "t" + year;

                }
                else if (aLine.startsWith("#c")){
                       conference = aLine.substring(2);
                       Line = Line + "t" + conference;
                }
                else if (aLine.startsWith("#index")){
                       index = aLine.substring(6);
                       Line = Line + "t" + index;
                }
                else if (aLine.startsWith("#%")){
                       cite = aLine.substring(2);
                       Line = Line + "t" + cite;
                       System.out.println(Line);
                }   
           }

          private final Path fFilePath;
          private final static Charset ENCODING = StandardCharsets.UTF_8;  

        }

I wanted to do something like this but it has a syntax error on the next.

else if (aLine.startsWith("#%")){
                   cite = aLine.substring(2);
                   if(aLine.next.startsWith("#@"))
                   {
                      cite = "," + cite; 
                    }   
                   Line = Line + "t" + cite;
                   System.out.println(Line);
            }

Answers

To get the next line you will need to pass the scanner along as well. Currently you are passing a string which has no idea what the next line in the file is.

import java.sql.SQLException;
import java.util.Scanner;
import java.io.*;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.file.Path;
import java.nio.file.Paths;

public class Citation2{

    String title;
    String author;
    String year;
    String conference;
    String index;
    String cite;
    String abstracts;
    String Line;

    public static void main (String[] args) throws SQLException,
    ClassNotFoundException, IOException{

        Citation2 parser = new Citation2("test.txt");
        parser.processLineByLine();

    }

    public Citation2(String aFileName){
        fFilePath = Paths.get(aFileName);
    }

    public final void processLineByLine() throws IOException, ClassNotFoundException, SQLException {
        try (Scanner scanner =  new Scanner(fFilePath, ENCODING.name())){
            String nextLine = null;
            if(scanner.hasNextLine()){
                nextLine = scanner.nextLine();
            }
            while (nextLine!=null){
                nextLine = processLine(nextLine, scanner);
            }      
        }
    }

    protected String processLine(String aLine, Scanner scanner) throws ClassNotFoundException, SQLException {
        String nextLine = null;

        if (aLine.startsWith("#*")) {
            title = aLine.substring(2);
            Line = title;
        } 
        else if (aLine.startsWith("#@")){
            author = aLine.substring(2);
            Line = Line + "t" + author;
        }
        else if (aLine.startsWith("#t")){
            year = aLine.substring(2);
            Line = Line + "t" + year;

        }
        else if (aLine.startsWith("#c")){
            conference = aLine.substring(2);
            Line = Line + "t" + conference;
        }
        else if (aLine.startsWith("#index")){
            index = aLine.substring(6);
            Line = Line + "t" + index;
        }
        else if (aLine.startsWith("#%")){
            cite = aLine.substring(2);
            while(scanner.hasNextLine() && (nextLine = scanner.nextLine()).startsWith("#%"))
            {
                cite += "," + nextLine.substring(2); 
            }   
            Line = Line + "t" + cite;
            System.out.println(Line);
        } 
        if(nextLine== null && scanner.hasNextLine()){
            nextLine = scanner.nextLine();
        }
        return nextLine;
    }

    private final Path fFilePath;
    private final static Charset ENCODING = StandardCharsets.UTF_8;  

}

You should consider using a StringBuilder, it might be more efficient if you have a large file, since you don’t have to create new objects every time you concatenate.

Here is an example:

StringBuilder line = new StringBuilder();

protected void processLine(String aLine) throws ClassNotFoundException, SQLException {
    if (aLine.startsWith("#*")) {
        line.append(aLine.substring(2));
    } else if (aLine.startsWith("#@")) {
        line.append("t");
        line.append(aLine.substring(2));
    } else if (aLine.startsWith("#t")) {
        line.append("t");
        line.append(aLine.substring(2));
    } else if (aLine.startsWith("#c")) {
        line.append("t");
        line.append(aLine.substring(2));
    } else if (aLine.startsWith("#index")) {
        line.append("t");
        line.append(aLine.substring(6));
    } else if (aLine.startsWith("#%")) {
        line.append("t");
        line.append(aLine.substring(2));
    } else if (aLine.startsWith("#!")) {
        line.append("n");
    }
}

Nice thing to do would be – create the scanner instance inside

public final void processLineByLine() throws IOException, ClassNotFoundException, SQLException {
    try (Scanner scanner =  new Scanner(fFilePath, ENCODING.name())){   
        processLine(scanner);
    }
}

and pass it to processLine. Inside processLine do as below

protected void processLine(Scanner scanner) throws ClassNotFoundException, SQLException {
    String nextLine = null;
    while (scanner.hasNextLine()) {
        nextLine = scanner.nextLine();
        //execute the if-else logic here
    }

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String.startsWith() to detect more than one line and parse it into the same variable – Artificial Intelligence

Answers