Java 如何确保HashMap的每次迭代都是事务性的

我有一个方法可以从hashmap中删除值，而不删除键

HashMap的结构如下所示，注意Kennel和Dog都是Java对象：

Map<Kennel, List<Dog>> mapOfKennels;

---

重构您的代码，以便通过专用方法处理每个犬舍的移除。然后将@Transactional注释添加到此方法。例如在DogRepository中

@Transactional
public class DogRepository{

   public void deleteDogs(List<Dog> dogs){
       //delete all dogs
   }
}

然后在你的客户端代码中

   public void deleteDogsFromKennels(Map<Kennel, List<Dog>> mapOfKennelsAndDogs) {
    //For each Kennel in the Map
     for (Map.Entry<Kennel, List<Dog>> entry :mapOfKennelsAndDogs.entrySet()){
        String key = entry.getKey().getId();
        List<Dog> dogList = entry.getValue();
        try{
           dogRepository.deleteDogs(dogList);
        }
        catch(Exception ex){
            //log failed to delete kennel with key
         }
     }
   }

确保deleteDogs方法与deleteDogsFromKennels方法在单独的类中，否则事务将无法工作。

尝试在方法级别添加@Transactional，即deleteDogsFromKennels，或者在类级别添加@Transactional，如果您不想像@ekemChitsiga在下面的回答中所说的那样重构代码。这应该行得通。

   public void deleteDogsFromKennels(Map<Kennel, List<Dog>> mapOfKennelsAndDogs) {
    //For each Kennel in the Map
     for (Map.Entry<Kennel, List<Dog>> entry :mapOfKennelsAndDogs.entrySet()){
        String key = entry.getKey().getId();
        List<Dog> dogList = entry.getValue();
        try{
           dogRepository.deleteDogs(dogList);
        }
        catch(Exception ex){
            //log failed to delete kennel with key
         }
     }
   }