Lambda和cast交点类型（Eclipse编译器bug） [英] Lambda and cast intersection type (Eclipse compiler bug)

问题描述

  public static void main（String [] args）{
 Calculator test =（Calculator& Sumator）（a，b） - > a + b; 
 System.out.println（test.calculate（2，3））; 
 
 Sumator sumator =（Calculator& Sumator）（a，b） - > a + b; //编译，但抛出一个异常
 sumator.test（）; 
 
 both =（Both）（a，b） - > a + b; //不编译
} 
 
接口计算器{
 public int calculate（int a，int b）; 
} 
 
接口Sumator {
 public int test（）; 
 
 public int test3（int a，int b）; 
} 
 
 //两种类型的交集
接口两个扩展Sumator，Calculator {
 
} 
  

这是一种误导，我知道关于转换为交叉路口类型，我已经阅读了jls，但仍然令人困惑。

这对于

 可序列化&可比较的
  

将编译，因为这两者之间的结果（合成类型）是一个功能界面，为什么：

  Calculator& Sumator 
  

工程？该合成类型不是功能界面。

解决方案

这是一个 Eclipse中的错误已经针对Eclipse Neon（4.6）修改了里程碑6。

So, why does this code compile?

public static void main(String[] args) {
    Calculator test = (Calculator & Sumator) (a, b) -> a + b;
    System.out.println(test.calculate(2, 3));

    Sumator sumator = (Calculator & Sumator) (a, b) -> a + b; // does compile, but throws an Exception
    sumator.test();

    Both both = (Both) (a, b) -> a + b; // does not compile
}

interface Calculator {
    public int calculate(int a, int b);
}

interface Sumator {
    public int test();

    public int test3(int a, int b);
}

// intersection of both types
interface Both extends Sumator, Calculator {

}

This is sort of misleading, I do know about casting to an intersection type, I've read the jls, but still confusing.

It sort of makes sense why

 Serializable & Comparable 

would compile, since the result (the synthetic type) between those two is a functional interface, but why does :

 Calculator & Sumator 

works? That synthetic type is not a functional interface.

解决方案

This was a bug in Eclipse which has been fixed for milestone 6 towards Eclipse Neon (4.6).

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