String fileName = file.getName();
int dotPos = fileName.lastIndexOf(".");
String extension = fileName.substring(dotPos + 1).toLowerCase();
if (extension.equals(JSimConstants.PDBEXTENSION)) {
PDBViewer pdbViewer = new PDBViewer(file);
return pdbViewer;
} else if (extension.equals(JSimConstants.XVGEXTENSION)) {
Plotter plotter = new Plotter(fileContent);
return plotter;
}