NullPointerException when dealing with files

[Trenton]

Gives NullPointerException to work with the files, and it doesn't work, help me figure it out. I'm building a variable. file where the file is recorded by the chosen user in the same class,

File file;
    public File getFile() {
        return file;
    }
if (cmd.equals("Quelldatei auswählen")) {
            JFileChooser fileChooser = new JFileChooser();
            fileChooser
                    .setFileSelectionMode(JFileChooser.FILES_ONLY);
            int ret = fileChooser.showDialog(this, "auswählen");
            if (ret == JFileChooser.APPROVE_OPTION) {
            file= fileChooser.getSelectedFile().getAbsoluteFile();
            contentPane.add(new JLabel("Quelldatei ist: " + file));

and challenge him from the classroom method by setting up the object of this class to challenge this file through. gd.getFile()

GUIDialog gd;

public void doit() {

try {

gd=new GUIDialog();

in = new BufferedReader(new FileReader(gd.getFile()));

but when a cat is pressed on the button, it must take this transferable file and transform it, it's NullPointerException, pointing on this line. in = new BufferedReader(new FileReader(gd.getFile()));what's being done here is wrong, help counsel.

[emerson]

Then you can simply make a comparison in a separate method, and in the designer, for example, make it:

public File getFile() { sravnenie(); return file; }

Thank you very much, but it's only through a 1-block strike.