从休眠表中选择全部 [英] Select all from a table hibernate

问题描述

所以我有下面的代码：

  Query query = session.createQuery（from Weather）; 
列表< WeatherModel> list = query.list（）; 
 WeatherModel w =（WeatherModel）list.get（0）; 
  

我不想从表格中获取所有项目，但我仍然收到以下错误：（第23行是我创建查询的地方）

  java.lang.NullPointerException $ b $ action.WeatherAction.validate （WeatherAction.java:23）
 at com.opensymphony.xwork2.validator.ValidationInterceptor.doBeforeInvocation（ValidationInterceptor.java:251）
 at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept（ValidationInterceptor.java ：263）............ 
  

有什么问题？ p>

解决方案

  Query query = session.createQuery（from Weather）; //你将得到Weayher对象
 List< WeatherModel> list = query.list（）; //您正在以列表形式访问< WeatherModel> 
  

它们都是不同的实体

  Query query = session.createQuery（from Weather）; 
 
列表<天气> list = query.list（）; 
 
天气w =（天气）list.get（0）; 
  

So I have this following code:

Query query = session.createQuery("from Weather");
        List<WeatherModel> list = query.list();
        WeatherModel w = (WeatherModel) list.get(0);

I wan't to get all the items from the table Weather, but I keep getting the following error:(line 23 is where I create the query)

java.lang.NullPointerException
    at action.WeatherAction.validate(WeatherAction.java:23)
    at com.opensymphony.xwork2.validator.ValidationInterceptor.doBeforeInvocation(ValidationInterceptor.java:251)
    at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:263)............

What's the problem?

解决方案

Query query = session.createQuery("from Weather"); //You will get Weayher object
List<WeatherModel> list = query.list(); //You are accessing  as list<WeatherModel>

They both are different entities

Query query = session.createQuery("from Weather"); 

 List<Weather> list = query.list(); 

Weather w = (Weather) list.get(0);

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