Question

I get an error on:

line = node_reader.readLine();

When the text file is empty I get a NullPointerException error. If there is data on the text I do not get the error. What am I doing wrong?

void file_open () {

    String line = "test";
    BufferedReader node_reader;
    node_reader = createReader("nodedata.txt");

    while (line !=null ) {   

        try {

            line = node_reader.readLine();

            if ( line != null ) {
                String[] pieces = split(line, TAB);
                int a = int(pieces[0]);
                int b = int(pieces[1]);
                int c = int(pieces[2]);
                int d = int(pieces[3]);
                int e = int(pieces[4]);

                listofNodes.add(new Node(a, b, e));  //
            }

        } catch (IOException e) {
            e.printStackTrace();
            line = null;
        }
    }
}

This is the text file:

138 102 100 36  0
95  293 100 36  1

Answer 1

The problem lies in

node_reader = createReader("nodedata.txt");

Inside this method, the file is probably not opened correctly. Go to this method and validate that the method correctly creates a BufferedReader.