单对双链表(single vs double Linked list)

 成员未在任何地方初始化。 
 
//initialize
member = new member[15]; // 15 is just an example.
 
 另一方面，如果大小不固定，则应考虑使用List 。 
 
List<member> members = new ArrayList<member>();
 
 在onclick方法中， 
 
members.add(new member());
 
 并访问项目， 
 
member m = members.get(0); // first item in the list
 
 要迭代所有项目， 
 
   for(member m : members){
      // m is your member object
   }

member is not initialized in anywhere.
 
//initialize
member = new member[15]; // 15 is just an example.
 
On the other hand, if the size is not fixed, you should consider using List instead.
 
List<member> members = new ArrayList<member>();
 
and in onclick method,
 
members.add(new member());
 
And to access the items,
 
member m = members.get(0); // first item in the list
 
To iterate all items,
 
   for(member m : members){
      // m is your member object
   }