这段java代码的语法如何理解？

public Object get(Object key) {
     Object obj = null;
     if(map.get(key) instanceof Object[]) {
         Object[] arr = (Object[])map.get(key);
        obj = request == null ? arr:(request.getParameter((String)key) == null ? arr:arr[0]);
     } else {
        obj = map.get(key);
     }
    return obj;
}