用泛型投射到内部类

Question

请考虑以下代码:

public class Outer<T>  {

    public class Inner{
    }

    public static <T> Outer<T>.Inner get(){
        Object o = new Object();
        return (Outer<T>.Inner)o;
    }

    public static void main(String[] args) throws Exception {
        Outer.<String>get();
    }
}

此代码在Eclipse中成功编译,但无法编译javac:

Outer.java:10: ')' expected
        return (Outer<T>.Inner)o;
                        ^
Outer.java:10: ';' expected
        return (Outer<T>.Inner)o;
                         ^
Outer.java:10: illegal start of expression
        return (Outer<T>.Inner)o;
                              ^
3 errors

这是javacEclipse中的错误吗？

如果我将演员阵容改为(Outer.Inner)o编译,虽然有警告:

日食:

Outer.Inner is a raw type. References to generic type Outer<T>.Inner should be parameterized

javac的:

Outer.java:10: warning: [unchecked] unchecked conversion
found   : Outer.Inner
required: Outer<T>.Inner
        return (Outer.Inner)o;
               ^
1 warning

Javac版本: 1.6.0_21

Answer 1

我发现这是 javac 编译器中的一个错误，现已修复。JDK 7b100 可以正常编译。

请参阅https://bugs.java.com/bugdatabase/view_bug?bug_id=6665356