Reading a Text File

Below is a short code snippet showing how to read lines of data from a text file:

public class ReadSource
{
public static void main(String[] arguments)
{
    try
    {
        FileReader file = new FileReader("ReadSource.java");
        BufferedReader buff = new BufferedReader(file);
        String line;

        line = buff.readLine();
        while (line != null)
        {
            System.out.println(line);
            line = buff.readLine();
        }
        buff.close();

    }
    catch (IOException e)
    {
        System.out.println("Error " + e.toString());
    }
}
}

Note that the file being read in is called ReadSource.java, and it is in the current directory (you will need to figure out what that means if you are using an IDE).

This code follows what I call The Standard Structure of a While Loop that Gets Input

    Get Input
    While (input ok)
    {
        Process
        Get Input
    }

When reading from a datafile, the check for "input ok" will be to check if the input is null.
The processing is whatever your program needs to do with the data.

How do you tokenize a String? Below is an example; you can use other ways of doing this, if you like (for instance split()).

    StringTokenizer st = new StringTokenizer("this is a test");
    while (st.hasMoreTokens())
    {
        System.out.println(st.nextToken());
    }

To convert to an inteer you can use the type-wrapper class Integer: int x = Integer.parseInt(str);