当类实现相同的接口时,Lambda表达式因LambdaConversionException而失败? [重复]

问题描述 投票:1回答:1

我很惊讶,为什么lambda表达式无法在运行时正确调用。这是一个类型推断错误?工作aournd示例取消注释显式类型参数声明。

public class LambdaConversionTest {
    @Test
    public void whyDidLambdaExpressionFailsWithLambdaConversionException() {
        try {
            //      v--- when uncomment it, the behavior is what I expected
            Stream./*<Collector>*/of(new Robot(), new Puller())
                  .flatMapToInt(Collector::stream).sum();
            fail("fails with expected behavior");
        } catch (BootstrapMethodError why) {
            assertThat(why.getCause().getMessage()
                 ,containsString("Invalid receiver type interface "));
        }
    }

    interface Marker {
    }

    interface Collector {
        IntStream stream();
    }

    class Robot implements Collector, Marker {
        @Override
        public IntStream stream() {
            return IntStream.empty();
        }
    }

    class Puller implements Collector, Marker {
        @Override
        public IntStream stream() {
            return IntStream.empty();
        }
    }
}
java java-8
1个回答
2
投票

对于这个特殊的this JDK bug实例,应该注意的是,如果你在Marker之后声明接口Collector它不会失败

失败:

interface Marker {}

interface Collector {
    IntStream stream();
}

通过:

interface Collector {
    IntStream stream();
}
interface Marker {}
© www.soinside.com 2019 - 2024. All rights reserved.