関数を呼び出すときにエラーが発生しLoadInput()ます...
private void loadInput() {
        String fn;
        FileDialog fd= new FileDialog((Frame)this.getParent(), "Load RS-274D/X file...", FileDialog.LOAD);
        fd.setVisible(true);
        fn = fd.getFile();
        if (fn != null)
            readInput(fn);
    }
そしてここに例外があります:
Exception in thread "AWT-EventQueue-1" java.lang.Error: Unresolved compilation problem: 
    The constructor FileDialog(RS274X, String, int) is undefined
    at RS274X.loadInput(RS274X.java:251)
    at RS274X.actionPerformed(RS274X.java:165)