EditText Value in a dialog

I dont understand, the dialog and everything works but as soon as I get the value from the EditText and assign it to val, run the app it crashes within the onClick on success.

I get an error: Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference

public void createDialogBox() {

    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    // Get the layout inflater
    LayoutInflater inflater = this.getLayoutInflater();

    // Inflate and set the layout for the dialog
    // Pass null as the parent view because its going in the dialog layout
    //


    builder.setView(R.layout.custom_dialog)
            .setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {
                    // On success

                    EditText text = (EditText) findViewById(R.id.shopping_list_recycler_view);
                    String val = text.getText().toString();

                    adapter = new ShoppingListViewAdapter(test, MainShoppingListViewActivity.this);
                    recyclerView.setAdapter(adapter);

                    adapter.addTest(new Data(val, "Created by: Me"));
                }
            })
            .setNegativeButton(android.R.string.no, new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {
                    // On failure
                    Toast.makeText(MainShoppingListViewActivity.this, "Failed", Toast.LENGTH_SHORT).show();
                }
            })
            // Desired icon for the dialog box
            .setIcon(android.R.drawable.ic_dialog_alert)
            .show();
}