Question

我有一个String，我想在查询中用作参数。我的代码如下：

List<EventPayload> mylist=eventpojo.getEventPayload();

            for(EventPayload array : mylist)
            {
                System.out.println("Comment Text :"+array.getCommentText());
                System.out.println("Comment Type :"+array.getCommentType());
                System.out.println("Comment Id :"+array.getCommentId());
                System.out.println("Email id :"+array.getComment_email());
                String email1=array.getComment_email();
            }

            EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("jcg-JPA");
            EntityManager em = entityManagerFactory.createEntityManager();

            String email=em.createQuery("SELECT user_id FROM UserInfo WHERE email_id = "+email1).toString();

我想在查询循环外使用String email1。如何实现这个？

Answer 1

email1 位于forloop内部，因此范围缩小到该细分受众群......

声明外部，也将变量的范围设置为可在外部访问...

List<EventPayload> mylist=eventpojo.getEventPayload();
String email1=null;  //HERE!!
for(EventPayload array : mylist)
{
    System.out.println("Comment Text :"+array.getCommentText());
    System.out.println("Comment Type :"+array.getCommentType());
    System.out.println("Comment Id :"+array.getCommentId());
    System.out.println("Email id :"+array.getComment_email());
    email1=array.getComment_email();
}

EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("jcg-JPA");
EntityManager em = entityManagerFactory.createEntityManager();

String email=em.createQuery("SELECT user_id FROM UserInfo WHERE email_id = "+email1).toString();

Answer 2

简短回答：你不能

长答案/进一步的问题：你想做什么？

为每个EventPayload触发一个SQL - ＆gt;然后在循环中执行此操作

为一个不同的EventPayload触发SQL - ＆gt;在列表中查找对象（或过滤列表）并执行该对象的查询

我想在JAVA中使用FOR循环之外的变量

2 个答案: