我想在Java中插入数组时遇到问题

Question

class Data {

    private String Name;
    private String Family;
    private int StCode;
    private int Average;
    private int Link;

    //insert start
    public void Insert(String name, String family, int stcode, int average) {
        if (flag = false) {
            Startdata = newadd;
            flag = true;
        }
        if (PointerCount == 0) {
            data[newadd].Name = name;
            data[newadd].Family = family;
            data[newadd].StCode = stcode;
            data[newadd].Average = average;
            data[newadd].Link = -1;

            if (head != -1) {
                data[head].Link = newadd;
            }

            head = newadd;
            newadd++;
        }
    }

错误

Exception in thread "AWT-EventQueue-0" java. lang. NullPointerException

当我想像data[0].Name=" ";一样插入时，出现此错误。