[英]Scala type mismatch with generics
I'm really new to Scala and I'm try to convert some JSF controller to Scala to do some test. 我真的是Scala的新手,我尝试将一些JSF控制器转换为Scala进行测试。 The code is the following:
代码如下:
abstract class BaseListBean[TENTITY <: AnyRef, TID <: AnyRef] extends Serializable {
@BeanProperty var current:TENTITY = _
@BeanProperty var lazyDataModel: LazyDataModel[TENTITY] = _
def initLazyDataModel(): LazyDataModel[TENTITY] = {
val model:LazyDataModel[TENTITY] = new LazyDataModel[TENTITY]() {
override def load(first: Int, pageSize: Int, sortField: String, sortOrder: SortOrder, filters: util.Map[String, AnyRef]): util.List[TENTITY] = {
val paginationInfo:PaginationInfo = new PaginationInfo()
paginationInfo.setFromRecord(first)
paginationInfo.setPageSize(pageSize)
paginationInfo.setSortBy(Array(sortField))
paginationInfo.setDirections(if (SortOrder.ASCENDING == sortOrder) Array(Direction.Asc) else Array(Direction.Desc))
val advisoryPaginatedResult:PaginatedResult[TENTITY] = getBaseCRUD.read(paginationInfo)
setRowCount(advisoryPaginatedResult.getTotalItems.toInt)
advisoryPaginatedResult getItems
}
override def getRowKey(obj: TENTITY): TID = getEntityKey(obj)
}
return model;
}
def init() = {
setLazyDataModel(initLazyDataModel())
}
def getEntityKey(obj: TENTITY) : TID
def getBaseCRUD() : BaseCRUD[TENTITY, TID]
def customInit() = {
}
}
The error on compile time is: 编译时错误为:
Error:(24, 34) type mismatch;
错误:(24,34)类型不匹配;
found : org.primefaces.model.org.primefaces.model.LazyDataModel[TENTITY]
找到了:org.primefaces.model.org.primefaces.model.LazyDataModel [TENTITY]
required: org.primefaces.model.org.primefaces.model.LazyDataModel[TENTITY]
必需:org.primefaces.model.org.primefaces.model.LazyDataModel [TENTITY]
val model:LazyDataModel[TENTITY] = new LazyDataModel[TENTITY]() {
I search for a solution but the problem still remaign. 我正在寻找解决方案,但问题仍然存在。 I try to reproduce with simpler code like this:
我尝试使用以下更简单的代码进行重现:
abstract class ExampleGenerics[T <: AnyRef, V <: AnyRef] {
@BeanProperty var list:util.AbstractMap[T, V] = _
def initList() : util.AbstractMap[T, V] = {
val model:util.AbstractMap[T, V] = new util.AbstractMap[T, V]() {
override def entrySet(): util.Set[Entry[T, V]] = {
return null;
}
}
return model
}
def init() = {
setList(initList());
}
}
But this will work. 但这会起作用。 Someone can help?
有人可以帮忙吗? Thanks
谢谢
I found the problem: 我发现了问题:
This is the head of LazyDataModel<T>
: 这是
LazyDataModel<T>
的头:
public abstract class LazyDataModel<T> extends DataModel<T> implements SelectableDataModel<T>, Serializable { /*...*/ }
The class inherit from DataModel<T>
. 该类继承自
DataModel<T>
。
In my pom.xml I have 在我的pom.xml中
<dependency>
<groupId>javax.faces</groupId>
<artifactId>javax.faces-api</artifactId>
<version>2.0</version>
<scope>provided</scope>
</dependency>
and also 并且
<dependency>
<groupId>javaee</groupId>
<artifactId>javaee-api</artifactId>
<version>5</version>
<scope>provided</scope>
</dependency>
The class DataModel<T>
is in the jsf 2 packages but also in javaee-api there is DataModel
class (without generic). DataModel<T>
类位于jsf 2软件包中,但在javaee-api中也有DataModel
类(无通用)。 So the compiler go wrong. 因此编译器出错。 The resolution is to modify the pom with the following dependencies:
解决方案是使用以下依赖项来修改pom:
<dependency>
<groupId>javax.ejb</groupId>
<artifactId>ejb-api</artifactId>
<version>3.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.faces</groupId>
<artifactId>javax.faces-api</artifactId>
<version>2.0</version>
<scope>provided</scope>
</dependency>
I can't use jee6 api dependencies cause I'm using jee5 compatible app server with JSF2.0 upgrade. 我无法使用jee6 api依赖项,因为我正在将Jee5兼容的应用服务器与JSF2.0升级一起使用。
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