查询数据库数据使用HashMap保存

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最新推荐文章于 2025-03-13 16:01:23 发布

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文章标签： hashmap 数据库 object string menu list

本文链接：https://blog.youkuaiyun.com/yqq1040027506/article/details/7178085

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博客内容描述了在查询数据库后使用HashMap保存数据时遇到的问题。原本的代码会导致只保存最后一条数据，通过将Map初始化移到while循环内部解决了这个问题，从而成功保存所有查询结果。

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public List<Map<String, Object>> findsousuosearch(String search) {
  List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
  Map<String, Object> map = new HashMap<String, Object>();
  Cursor cursor = db.rawQuery("SELECT pm.id,pm.cname,pm.cname_pywb,pm.spunit,pm.price," +
    "pmo.photo,pmo.comment FROM posbase_menu as pm,posbase_menu_ole as pmo where pmo.masterid=pm.id and pm.cname_pywb like 'B%'",null);
  while (cursor.moveToNext()) {
   int id =cursor.getInt(cursor.getColumnIndex("id"));
   String cname = cursor.getString(cursor.getColumnIndex("cname"));
   String cname_pywb = cursor.getString(cursor.getColumnIndex("cname_pywb"));
   String spunit = cursor.getString(cursor.getColumnIndex("spunit"));
   int price=cursor.getInt(cursor.getColumnIndex("price"));
   byte[] photo =cursor.getBlob(cursor.getColumnIndex("photo"));
  String comment=cursor.getString(cursor.getColumnIndex("comment"));
     map.put("backimg", id);
   map.put("cname", cname);
   map.put("cname_pywb", cname_pywb);
   map.put("spunit", spunit);
   map.put("price", price);
   map.put("photo", photo);
   map.put("comment", comment);
   list.add(map);
  }
  cursor.close();
  return list;
}

但是查询的时候获取的就是最后一条添加的数据

我不知道错在了哪里。。

然后我又从网上查了一下设置map初始化的时候我放在了最外面

然后我是这样设置的

public List<Map<String, Object>> findsousuosearch(String search) {
  List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
  Map<String, Object> map = null;
  Cursor cursor = db.rawQuery("SELECT pm.id,pm.cname,pm.cname_pywb,pm.spunit,pm.price," +
    "pmo.photo,pmo.comment FROM posbase_menu as pm,posbase_menu_ole as pmo where pmo.masterid=pm.id and pm.cname_pywb like 'B%'",null);
  while (cursor.moveToNext()) {
   int id =cursor.getInt(cursor.getColumnIndex("id"));
   String cname = cursor.getString(cursor.getColumnIndex("cname"));
   String cname_pywb = cursor.getString(cursor.getColumnIndex("cname_pywb"));
   String spunit = cursor.getString(cursor.getColumnIndex("spunit"));
   int price=cursor.getInt(cursor.getColumnIndex("price"));
   byte[] photo =cursor.getBlob(cursor.getColumnIndex("photo"));
  String comment=cursor.getString(cursor.getColumnIndex("comment"));
   map=new HashMap<String, Object>();
   map.put("backimg", id);
   map.put("cname", cname);
   map.put("cname_pywb", cname_pywb);
   map.put("spunit", spunit);
   map.put("price", price);
   map.put("photo", photo);
   map.put("comment", comment);
   list.add(map);
  }
  cursor.close();
  return list;
}