Java ListView抛出NullPointerException

我在活动布局上有一个自定义的ListView DragSortListView，当我启动活动时，它会抛出NullPointerException并关闭应用程序，但当我下次启动此活动时，它会正常工作。如何删除此错误。 日志

适配器

private class OrderAdapter extends ArrayAdapter<Order>{
          public OrderAdapter(List<Order> list) {
              super(MainActivity.this, R.layout.order_list_item,R.id.address,list);
          }
          public View getView(int position, View convertView, ViewGroup parent) {
                  View v = super.getView(position, convertView, parent);
                        TextView item=(TextView) v.findViewById(R.id.address);
                          TextView subitem=(TextView) v.findViewById(R.id.client);
                          item.setTextColor(Color.WHITE);
                          subitem.setTextColor(Color.WHITE);
                          item.setText(getItem(position).order_address);
                          subitem.setText(getItem(position).order_client);

                          TextView pos = (TextView) v.findViewById(R.id.pos_number);
                          pos.setText(String.valueOf(getItem(position).position_number));

                          ImageView state = (ImageView) v.findViewById(R.id.checkItem);
                          state.setVisibility(View.VISIBLE);
                          if (getItem(position).order_status == 3)
                              state.setBackgroundResource(drawable.check_cancelled);
                          if (getItem(position).order_status == 2)
                              state.setBackgroundResource(drawable.check_checked);
                          if (getItem(position).order_status == 0)
                              state.setBackgroundResource(drawable.check_nb);
                          if (getItem(position).order_status == 1)
                          {
                              state.setVisibility(View.GONE);
                          }
                  return v;

初始化

c_orders = new ArrayList<Order>();
adapter = new OrderAdapter(c_orders);
myList=(DragSortListView)findViewById(R.id.dsvlist);
myList.setAdapter(adapter);
myList.setDropListener(onDrop);
myList.setRemoveListener(onRemove);
myList.setOnItemClickListener(listener);

而不是打电话

View v = super.getView(position, convertView, parent);

自己膨胀视野

LayoutInflater inflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
view v = inflater.inflate(R.layout.your_layout_name, parent, false);
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注意：为了了解适配器的工作原理，您应该阅读教程？提高listview性能的最佳方法是什么

发布你的代码是为了什么？用于初始化listview还是什么？是的，在哪里设置适配器？并初始化它

LayoutInflater inflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
view v = inflater.inflate(R.layout.your_layout_name, parent, false);
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