我可以解决这个问题,但我无法理解它,所以我要求一些解释(也许还有一个更好的问题标题)。枚举编译错误中的java匿名类
请考虑一下:
public class TBGService {
// TBGObject is an abstract base class which is extended by model classes
public <T> T doGet(TBGObject model) throws TBGServiceException {
String uri = model.buildUrl(repository) + model.getObjectKey();
GetMethod method = new GetMethod(uri);
T returned = execute(method, credentials, model.getClass());
return returned;
}
}
这:
public enum TBGTaskAttributes {
private TBGTaskAttributes(String id, String type, String label, Object... flags) {
builder = new TaskAttributeBuilder();
builder.withId(id).withLabel(label);
for (Object flag : flags) {
processFlag(flag);
}
}
public abstract String getValueFromIssue(TBGIssue issue);
public abstract void setValueInIssue(TBGIssue issue, String value);
}
当我写这篇文章的代码来定义一个枚举项:
PROJECT(TaskAttribute.PRODUCT, TaskAttribute.TYPE_SINGLE_SELECT, "Project", new OptionProvider() {
@Override
public Set<Entry<String, String>> getOptions(TaskRepository repository) {
try {
List<TBGProject> list = TBGService.get(repository)
.doGet(new TBGProjects()).getProjects();
[...]
return map.entrySet();
} catch (TBGServiceException e) { [...] }
return null;
}
}) {
@Override
public String getValueFromIssue(TBGIssue issue) {
return issue.getProjectKey();
}
@Override
public void setValueInIssue(TBGIssue issue, String value) {
issue.setProjectKey(value);
}
},
[... other items ...]
我得到编译器错误(也蚀自动完成不起作用):
The method getProjects() is undefined for the type Object
,如果我悬停doGet方法时,Eclipse其显示为像定义:
<Object> Object TBGService.doGet(TBGObject model)
在其他地方,悬停示出正确的签名:
<TBGProjects> TBGProjects TBGService.doGet(TBGObject model)
当与参数new TBGProjects()
调用。
只是改变:
List<TBGProject> list = TBGService.get(repository)
.doGet(new TBGProjects()).getProjects();
有:
TBGProjects projects = TBGService.get(repository).doGet(new TBGProjects());
List<TBGProject> = projects.getProjects();
使得它的工作。但是这里发生了什么?我错过了什么?
BTW,传递一个类的实例一样,是非常低效的。您应该接受'Class'参数并改为传递'TBGProjects.class'。 –
SLaks
我明白了;但实际上,传递的类包含抽象超类所需的逻辑。入口点知道调用构造器的输入,服务(作为json客户端)除抽象行为外对此一无所知。将尝试为这个设计找到一个更好的模式。 –
您可能想要在类上使用注释而不是'getObjectKey()'。 – SLaks