Question

so i’ve worked on hours end to come up with this code

public class instructorIO
{
    static Map<String, String> instructors;


    public static Map<String, String> getInstructors()
    {
        try
        {
          BufferedReader in = new BufferedReader( new FileReader("instructor.txt"));

             instructors = new LinkedHashMap<String, String>();

             String line;

            while(((line = in.readLine()) != null))
            {
                line = in.readLine();
                String[] val = line.split("<>");
                String ID = val[0];
                String name = val[1];

                instructors.put(ID, name);
            }
            in.close();
        }
        catch(IOException ioe)
        {
            ioe.printStackTrace();
        }

        return instructors;
    }
}

when i try to display all the hashmap values in my text area, only hash IDs 2,6, and 4 are displayed. There are a total of 6… what am i doing wrong?

also when i try to do that with another text file, i get a Exception in thread “main” java.lang.NullPointerException
at String[] val = line.split(“<>”);

Answer 1

You are reading two lines at a time and only taking the second one:

        while(((line = in.readLine()) != null))
        {
            line = in.readLine();
            String[] val = line.split("<>");
            String ID = val[0];
            String name = val[1];

            instructors.put(ID, name);
        }

once in the while condition and again inside the loop body. I suggest you do it like this:

        while(((line = in.readLine()) != null))
        {                
            String[] val = line.split("<>");
            String ID = val[0];
            String name = val[1];

            instructors.put(ID, name);
        }