Converting Objects to Generics and Handling Exceptions

I have a few questions/concerns with parts of my Java code.

I created the following Vector objects in my class:

private Vector data;
private Vector dataLabels;
private Vector dataColors;

If I want to convert these vectors to generic (template) type, does that mean that I have to change Vector to Vector<?> ? Is there another way to convert it to generic type?

I am not sure what is wrong with this paint() method:

public void paint(Graphics g)
{
setSize(200,250);
Image duke = Toolkit.getDefaultToolkit().getImage("duke2.gif");
g.drawImage(duke, 80, 10, this);

for (int i = 0; i < data.size(); i++)
{
int yposition = 100+i*barWidth;

g.setColor((Color) dataColors.elementAt(i));

int barLength = ((Integer) data.elementAt(i)).intValue();
g.fillOval(100, yposition, barLength, barWidth);

g.setColor(Color.black);
g.drawString((String) dataLabels.elementAt(i), 20, yposition+10);
}
}

I keep getting a NullPointerException at the following line:
g.drawImage(duke, 80, 10, this);

I have tried catching it, but it never catches it. How do I catch the exceptions in this method?

I have also attached the gif file that is used in the paint() method.
duke2.gif