private BrowserInternalFrame openClassFromJar(File file) throws IOException {
ClasspathArchiveEntry entry = new ClasspathArchiveEntry();
entry.setFileName(file.getPath());
if (jarBrowser == null) {
jarBrowser = new ClasspathBrowser(this, null, "Classes in selected JAR file:", false);
}
jarBrowser.clear();
jarBrowser.setClasspathComponent(entry);
jarBrowser.setVisible(true);
String selectedClassName = jarBrowser.getSelectedClassName();