lambda 表达式中的返回类型错误
以下代码在 IntelliJ 和 Eclipse 中编译良好,但 JDK 编译器 1.8.0_25 会抱怨。首先是代码。
import java.util.function.Predicate;
public abstract class MyStream<E> {
static <T> MyStream<T> create() {
return null;
}
abstract MyStream<E> filter(MyPredicate<? super E> predicate);
public interface MyPredicate<T> extends Predicate<T> {
@Override
boolean test(T t);
}
public void demo() {
MyStream.<Boolean> create().filter(b -> b);
MyStream.<String> create().filter(s -> s != null);
}
}
javac 1.8.0_25 的输出为:
MyStream.java:18: error: incompatible types: incompatible parameter types in lambda expression
MyStream.<Boolean> create().filter(b -> b);
^
MyStream.java:18: error: incompatible types: bad return type in lambda expression
MyStream.<Boolean> create().filter(b -> b);
^
? super Boolean cannot be converted to boolean
MyStream.java:19: error: bad operand types for binary operator '!='
MyStream.<String> create().filter(s -> s != null);
^
first type: ? super String
second type: <null>
MyStream.java:19: error: incompatible types: incompatible parameter types in lambda expression
MyStream.<String> create().filter(s -> s != null);
^
Note: Some messages have been simplified; recompile with -Xdiags:verbose to get full output
4 errors
当我用 simply 替换时,JDK 编译成功。? super E
E
当我用 替换时,JDK 编译成功。filter(MyPredicate
filter(Predicate
由于它与JDK 1.8.0_60一起使用,我怀疑这是一个编译器错误。
有关导致此问题的原因以及何时修复的任何详细信息?