final BasicSplitPaneUI myUi = (BasicSplitPaneUI) jSplitPane0.getUI();
final BasicSplitPaneDivider divider = myUi.getDivider();
final JButton upArrowButton = (JButton) divider.getComponent(0);
for (ActionListener al: upArrowButton.getActionListeners()) {
upArrowButton.removeActionListener(al);
}
final JButton downArrowButton = (JButton) divider.getComponent(1);
for (ActionListener al: downArrowButton.getActionListeners()) {
downArrowButton.removeActionListener(al);
}