Question

import java.io.*;
import java.util.Scanner;
import java.util.StringTokenizer;

public class Filereader {
    public static void main(String[] args) throws IOException {

File fil = new File("trans1.txt");
FileReader inputFil = new FileReader(fil);
BufferedReader in = new BufferedReader(inputFil);

//Create scanner to read contents of a file
Scanner scanner = new Scanner(new File("trans1.txt"));

//Create an array to store contents of a file after reading them
String [] tall = new String [100];

int i = 0;

while(scanner.hasNext()){
//Create StringTokenizer object
   StringTokenizer st = new StringTokenizer(scanner.next(),"< , { } >", true);
   tall[i] = scanner.next();
   System.out.println(tall[i]);
   i++;
  }
    in.close();
  }
 }

I want to read contents of a file into an array using the code above and print the values stored in the array to screen. Each time i run the code i dont get the desired output,can someone please help. Contents of my file are as follows;

5 
<0,{p1}>
<0,{p1}>  -1-> <1>
<1,{p1}>  -2-> <2><3>
<2,{p0}>  -1-> <0>
<3,{p1}>  -1-> <4>
<4,{p0}>  -1-> <3>

Answer 1

Here’s how I’d do it:

package cruft;

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 = "data/trans1.txt";

    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();
        }
    }

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

        BufferedReader br = null;

        try
        {
            br = new BufferedReader(reader);
            Scanner scanner = new Scanner(br);
            while (scanner.hasNext())
            {
                StringTokenizer st = new StringTokenizer(scanner.next(), DEFAULT_DELIMITERS, true);
                while (st.hasMoreElements())
                {
                    tokens.add(st.nextToken());                    
                }
            }
        }
        finally
        {
            close(br);
        }

        return tokens;
    }

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

And here’s the output I’d get if I run it against your file:

C:\JDKs\jdk1.6.0_13\bin\java  cruft.FileTokenizer
[5, <, 0, ,, {, p1, }, >, <, 0, ,, {, p1, }, >, -1-, >, <, 1, >, <, 1, ,, {, p1, }, >, -2-, >, <, 2, >, <, 3, >, <, 2, ,, {, p0, }, >, -1-, >, <, 0, >, <, 3, ,, {, p1, }, >, -1-, >, <, 4, >, <, 4, ,, {, p0, }, >, -1-, >, <, 3, >]

You don’t say what output you expected.