Problems with my program involving arraylists, bufferedreader, methods, and overall forgetfullness of how java works.

Question

Hello everyone. I am having difficulties with a program that I have been working on all day. I am trying to read a text file and read each line one at a time. Take that line and make an arraylist of the words of the line. then using the index of the arraylist define terms with it.

public class PCB {

    public static void main(String arg[]) {
        read();
    }

    public static ArrayList read() {    
        BufferedReader inputStream = null;
        ArrayList<String> tokens = new ArrayList<String>();
        try {
            inputStream = new BufferedReader(new FileReader("processes1.txt"));

            String l;
            while ((l = inputStream.readLine()) != null) {
                Scanner tokenize = new Scanner(l);
                while (tokenize.hasNext()) {
                    tokens.add(tokenize.next());
                }
                return tokens;
            }
        } catch (IOException ioe) {
            ArrayList<String> nothing = new ArrayList<String>();
            nothing.add("error1");
            System.out.println("error");
            //return nothing;
        }
        return tokens;
    }
}

The error I am getting is it only reads the first line. What am I doing wrong? Thank you so much in advance

Answer 1

You have "return tokens;" in your while loop. Seems like that early return would effectively cut off processing on the first line.

Answer 2

Try changing your loop to the following. Note how I moved the return statement.

while ((l = inputStream.readLine()) != null) {
    Scanner tokenize = new Scanner(l);
    while (tokenize.hasNext()) {
        tokens.add(tokenize.next());
    }
}
return tokens; // <-- outside the loop

---

Edit: If you want to read the entire file and store the tokens of each line in a seperate array, then you could create an ArrayList of ArrayList.

public static ArrayList<ArrayList<String>> tokenizeFile(string filename) {    
    BufferedReader inputStream = new BufferedReader(new FileReader(filename));
    ArrayList<ArrayList<String>> lines = new ArrayList<ArrayList<String>>();

    while (true) {
        String line = inputStream.readLine();
        if (line == null) break;

        ArrayList<String> tokens = new ArrayList<String>();
        Scanner tokenizer = new Scanner(line);
        while (tokenizer.hasNext()) {
            tokens.add(tokenizer.next());
        }
        lines.Add(tokens);
    }
    return lines;
}

Note: My Java is rusty.

Answer 3

Simplify to this ...

        String l;
        while ((l = inputStream.readLine()) != null) {
            tokens.addAll(Arrays.asList(l.split(" ")));
        }

... creates a list of all tokens on all lines in the file (if that is what you want).