为什么这段代码没有用 javac 编译，但在 eclipse 中没有错误? [英] why is this code not compiling with javac but has no errors in eclipse?

问题描述

以下代码:

@Retention(RetentionPolicy.RUNTIME)
@Target( { ElementType.METHOD, ElementType.FIELD, ElementType.ANNOTATION_TYPE })
@Constraint(validatedBy = {
        MinTimeIntCoConstraintValidator.class, 
        MinTimeIntCoListConstraintValidator.class,
        MinTimeDoubleCoConstraintValidator.class, 
        MinTimeDoubleCoListConstraintValidator.class,
        })
@Documented
public @interface MinTimeValueCo
{
    int value();
    String message() default "value does not match minimum requirements";
    Class<?>[] groups() default { };
    Class<? extends Payload>[] payload() default {};
}

在eclipse中编译但在sun/oracle编译器中编译失败:

compiled in eclipse but fails to compile in sun/oracle compiler:

> MinTimeValueCo.java:19: illegal start of expression
>     [javac]       })
>     [javac]       ^
>     [javac] 1 error

这是因为 MinTimeDoubleCoListConstraintValidator.class, 后面的逗号造成的.

This happened because of the comma after MinTimeDoubleCoListConstraintValidator.class,.

当我删除逗号时它工作正常:

when I removed the comma it works fine:

@Constraint(validatedBy = {
        MinTimeIntCoConstraintValidator.class, 
        MinTimeIntCoListConstraintValidator.class,
        MinTimeDoubleCoConstraintValidator.class, 
        MinTimeDoubleCoListConstraintValidator.class
        })

我使用的是 jdk 1.6.0.10.
你知道为什么这是非法的并在 eclipse 中编译吗?

I am using jdk 1.6.0.10.
Do you know why this is illegal and compiling in eclipse?

推荐答案

这是 Java 6 的 javac 中的一个错误.JLS 允许尾随逗号在某些地方，Eclipse 编译器遵循此处的标准，而 Java 6 从不允许在任何地方使用尾随逗号.

This is a bug in Java 6's javac. The JLS allows trailing commas in some places and the Eclipse compiler follows the standard here while Java 6 never allows trailing commas anywhere.

您可以尝试使用 Java 7 中的 javac 和选项 -source 6 -target 6(以获得 Java 6 兼容的字节码)来编译您的代码.如果错误仍然存​​在，归档.它可能会得到修复.

You can try to compile your code with javac from Java 7 with the options -source 6 -target 6 (to get Java 6 compatible byte code). If the bug is still there, file it. It might get fixed.

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