public class Image
{
    public Image (int width, int height)
    {
        _width = width;
        _height = height;
    }

    private int _width;
    private int _height;
}
public class Image
{
    public Image (int width, int height, String data)
    {
        _width = width;
        _height = height;
        _data = data;
    }

    private int _width;
    private int _height;
    private String _data;
}
Update Image.java