De acordo com o Java, erro encontra-se no trecho abaixo:
[code]
…
buttonPanel3.setLayout(new BoxLayout(buttonPanel3,BoxLayout.X_AXIS));
buttonPanel4.setLayout(new BoxLayout(buttonPanel2,BoxLayout.Y_AXIS));
buttonPanel1.add(log);//use BoxLayout
buttonPanel1.add(ta1);
buttonPanel2.add(label1);
buttonPanel2.add(openButton);//use BoxLayout
buttonPanel3.add(ta2);
buttonPanel4.add(label2);
buttonPanel4.add(generateButton);
//Create a file chooser
fc = new JFileChooser();
//Add the button panels
add(buttonPanel1);
add(buttonPanel2);
…[/code]
A Classe completa encontra-se anexada.