调试器无法在Lambda中看到局部变量 [英] Debugger cannot see local variable in a Lambda

问题描述

我注意到当我的调试器在lambda内停止时将鼠标悬停在局部变量上时，它将报告找不到局部变量'variable_name'即使它是可见的在lambda中使用它。

I noticed that when I hover my mouse over a local variable when my debugger is stopped inside a lambda it will report Cannot find local variable 'variable_name' even if it's visible inside the lambda and it's used.

示例代码

public class Main {
    public static void main(String[] args) {
        String a = "hello_world";
        m1(a);
    }

    private static void m1(String a) {
        AccessController.doPrivileged((PrivilegedAction<String>) () -> {
            System.out.println("blala " + a);
            return "abc";
        });
    }
}

尝试使用中的断点System.out.println（blala+ a）; 并在之后返回abc并且它总是报告相同的错误。

Try with a breakpoint in System.out.println("blala " + a); and after return "abc" and it always report the same error.

我使用 AccessController.doPrivileged 因为它是我在原始代码中使用的，当然我使用的是Java 8.

I used AccessController.doPrivileged because it's what I used in my original code and of course i'm using Java 8.

它在 Watchers 和评估表达式中说同样的事情。

It says the same thing in Watchers and Evaluate Expression.

我尝试使用匿名类版本，调试器正确看到 a 的值

I tried using the "anonymous class" version and the debugger sees the value of a correctly

private static void m1(String a) {
    AccessController.doPrivileged(new PrivilegedAction<String>() {
        @Override
        public String run() {
            System.out.println("blala " + a);
            return "abc";
        }
    });
}

我遗漏了一些关于lambda表达式的东西，或者它是一个IntellIJ IDEA 14错误？

I'm missing something about lambda expressions or it's an IntellIJ IDEA 14 bug?

我现在不想报告错误，因为我已经报告了一个由我的代码而不是IntellIJ IDEA引起的错误，所以我想在之前确定做某事（因为我不经常使用Java 8，所以我可能错了）。

I don't want to report the bug right now because I already reported a bug that was caused by my code instead of IntellIJ IDEA, so I want to be sure before do something (and because I don't use Java 8 so often, so I could be wrong).

推荐答案

这似乎是是一个知道问题。根据JetBrains，这种行为的根本原因在于JDK。有关详细信息，请参阅： IDEA-126257

This appears to be a know issue. According to JetBrains the root causes of this behavior is with the JDK. For more info see: IDEA-126257

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