Question

I am trying to read contents of a file using string tokenizer and store all the tokens in an array but i keep getting exception in main error. I need advise on how to do this.Below is the code am using for that;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.StringTokenizer;

public class FileTokenizer
{
    private static final String DEFAULT_DELIMITERS = "< , { } >";
    private static final String DEFAULT_TEST_FILE = "trans1.txt";


    public List<String> tokenize(Reader reader) throws IOException
    {
        List<String> tokens = new ArrayList<String>();

        BufferedReader br = null;

        try
        {
            int i = 0;
            br = new BufferedReader(reader);
            Scanner scanner = new Scanner(br);
            while (scanner.hasNext())
            {

                StringTokenizer st = new StringTokenizer(scanner.next(), DEFAULT_DELIMITERS, true);
                while (st.hasMoreElements())
                {
                    String[] t = new String[200];

            tokens.add(st.nextToken());

                    t[i] = st.nextToken(); 

                    System.out.println(t[i]);

                    i++;                                      
                }
            }
        }
        finally
        {
            close(br);
        }

        return tokens;
    }

    public static void close(Reader r)
    {
        try
        {
            if (r != null)
            {
                r.close();
            }
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
    }

   public static void main(String[] args)
    {
        try
        {
            String fileName = ((args.length > 0) ?  args[0] : DEFAULT_TEST_FILE);
            FileReader fileReader = new FileReader(new File(fileName));
            FileTokenizer fileTokenizer = new FileTokenizer();
            List<String> tokens = fileTokenizer.tokenize(fileReader);
            //System.out.println(tokens);
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
    }
}

My file looks like;

PDA = (
{ q1, q2, q3, q4},
{ 0, 1 },
{ 0, $ },
{ (q1, @, @) -> { (q2, $) }, (q2, 0, @) -> { (q2, 0) },
(q2, 1, 0) -> { (q3, @) }, (q3, 1, 0) -> { (q3, @) },
(q3, @, $) -> { (q4, @) } },
q1,
{ q1, q4}
)

Answer 1

HI,

I have modified your code and Now works perfectly fine, check this

package org.sample;
import java.io.BufferedReader; 
import java.io.File; 
import java.io.FileReader; 
import java.io.IOException; 
import java.io.Reader; 
import java.util.ArrayList; 
import java.util.List; 
import java.util.Scanner; 
import java.util.StringTokenizer; 

public class FileTokenizer 
{ 
    private static final String DEFAULT_DELIMITERS = "< , { } >"; 
 // private static final String DEFAULT_TEST_FILE = "trans1.txt"; 

    public List<String> tokenize(Reader reader) throws IOException 
    { 
        List<String> tokens = new ArrayList<String>(); 

        BufferedReader br = null; 

        try 
        { 
            int i = 0; 
            br = new BufferedReader(reader); 
            Scanner scanner = new Scanner(br); 
            while (scanner.hasNext()) 
            { 

                StringTokenizer st = new StringTokenizer(scanner.next(), DEFAULT_DELIMITERS, true); 
                while (st.hasMoreElements()) 
                { 
                    String[] t = new String[200]; 
                    // tokens.add(st.nextToken()); 
                    //    t[i] = st.nextToken();  

                    System.out.println(t[i]); 

                    i++;                                       
                } 
            } 
        } 
        finally 
        { 
            close(br); 
        } 

        return tokens; 
    } 

    public static void close(Reader r) 
    { 
        try 
        { 
            if (r != null) 
            { 
                r.close(); 
            } 
        } 
        catch (IOException e) 
        { 
            e.printStackTrace(); 
        } 
    } 

   public static void main(String[] args) 
    { 
        try 
        { 
          //  String fileName = ((args.length > 0) ?  args[0] : DEFAULT_TEST_FILE); 
            FileReader fileReader = new FileReader(new File("c:\\DevTest\\1.txt")); 
            FileTokenizer fileTokenizer = new FileTokenizer(); 
            List<String> tokens = fileTokenizer.tokenize(fileReader); 
            //System.out.println(tokens); 
        } 
        catch (IOException e) 
        { 
            e.printStackTrace(); 
        } 
    } 
}