CaptureDeviceManager.getDeviceList () returns null

I'm encoded in javaonubuntu 11.10

The laptop webcam is working correctly and finds it /dev/v4l/. The Skype application can use the webcam and run.

I installed JMF, but I could not add environment variables.

Vector deviceList = CaptureDeviceManager.getDeviceList(new RGBFormat());
System.out.println(deviceList.toString());
if(!deviceList.isEmpty()){
    System.out.println("1");
    device = (CaptureDeviceInfo) deviceList.firstElement();
}
device = (CaptureDeviceInfo) deviceList.firstElement();
ml = device.getLocator();

I want to just capture an image in java.

What should I do to solve the problem or use instead of JMF?