Java泛型接口的实现 [英] Java generics interface implementation

问题描述

我有一个接口如下，

  public interface MethodExecutor {
< T>列表与LT; T> execute（List<>事实，Class< T>类型）throws Exception; 
} 
  

另外，我有一个类似下面的通用实现，

  public class DefaultMetodExecutor实现MethodExecutor {
 
 public< T>列表与LT; T>执行（List<>事实，Class< T>类型）抛出异常
 {
 List< T> result = null; 
 
 //一些执行
 
返回结果; 
} 
} 
  

这里没有编译问题，

但是这个接口的具体实现无法编译，如下所示。

  public class SpecificMetodExecutor实现MethodExecutor {
 
 public< Model1>列表与LT;型号1>执行（List< Model2>事实，Class< Model1>类型）抛出异常
 {
 List< Model1> result = null; 
 
 //特定于Model1和Model2的一些实现
 
返回结果; 
 
 
 $ / code $ / pre 
 
 
如何为一些定义实现这个接口对象？我需要使用类级别泛型吗？
解决方案 
您需要使 T 类类型参数，而不是方法类型参数。您不能用非泛型方法覆盖泛型方法。  
 
 
  public interface MethodExecutor< T> {
列表< T> execute（List<>事实，Class< T>类型）throws Exception; 
} 
 
 public class DefaultMethodExecutor实现MethodExecutor< Model1> {
公共列表< Model1>执行（List<>事实，类< Model1>类型）抛出异常
 {
 // ... 
} 
} 
  
如果 facts 的元素类型应该可以针对特定实现进行配置，您需要
  public interface MethodExecutor< T，F> {
列表< T> execute（List< ;? extends F> facts，Class< T> type）throws Exception; 
} 
  
 
I have an interface as follows,
public interface MethodExecutor {
    <T> List<T> execute(List<?> facts, Class<T> type) throws Exception;
}
Also, I have a generic implementation like below,
public class DefaultMetodExecutor implements MethodExecutor {

   public <T> List<T> execute(List<?> facts, Class<T> type) throws Exception
   {
     List<T> result = null;

      //some implementation

      return result;
  }
}
Upto this there is no compilation issues,


But a specific implementation of this interface fails to compile, The one which shown below.
public class SpecificMetodExecutor implements MethodExecutor {

   public <Model1> List<Model1> execute(List<Model2> facts, Class<Model1> type) throws Exception
   {
     List<Model1> result = null;

     //some implementation specific to Model1 and Model2

      return result;
  } 
}
How can I implement this interface for some of the defined objects? Do I need to go for class level generics?
解决方案
You need to make T a class type parameter, not a method type parameter.  You can't override a generic method with a non-generic method.  
public interface MethodExecutor<T> {
    List<T> execute(List<?> facts, Class<T> type) throws Exception;
}

public class DefaultMethodExecutor implements MethodExecutor<Model1> {
    public List<Model1> execute(List<?> facts, Class<Model1> type) throws Exception
    {
       //...
    }
} 
If the element type of facts should be configurable for a specific implementation, you need to make that a parameter too.
public interface MethodExecutor<T, F> {
    List<T> execute(List<? extends F> facts, Class<T> type) throws Exception;
}


                        
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