如何使这个变量引用“final”，如何让它干净地编译？

发布于 2024-11-05 08:45:33 字数 829 浏览 4 评论 0原文

我想将 result 变量设为 final，如何构建此代码以便干净地编译？我知道我过去曾这样做过，但我不记得我是如何构建它以使其发挥作用的。

下面的代码是一个稻草人示例，我试图清理的代码要复杂得多，这只是提炼出我想要完成的事情的本质。

private boolean someMethod()
{
    final boolean result;
    try
    {
        // do the logic here that might throw the following
        // exceptions
    }
    catch (final IOException ioe)
    {
        result = false;
    }
    catch (final ClassNotFoundException cnfe)
    {
        result = false;
    }

    return result;
}

我无法将 result = true 放入 try 块中，因为它不会使用两个 catch 块进行编译，并抱怨最终变量可能已被分配。

我无法将其放入 finally 块中，因为这会产生与 try 块中相同的抱怨？

我希望能够设置 result = 一次且仅一次。

那么你在哪里设置 result = true; 来获取它干净地编译？

原文

I want to make the result variable final, how do I structure this code so that this compiles cleanly? I know I have done this in the past, but I can't remember how I structured it to make it work.

The following code is a straw man example, the code I am trying to clean up is much more complicated, this is just distilling the essence of what I am trying to accomplish.

private boolean someMethod()
{
    final boolean result;
    try
    {
        // do the logic here that might throw the following
        // exceptions
    }
    catch (final IOException ioe)
    {
        result = false;
    }
    catch (final ClassNotFoundException cnfe)
    {
        result = false;
    }

    return result;
}

I can't put the result = true in the try block because it won't compile with both the catch blocks complaining that the final variable might already be assigned.

I can't put it in a finally block because that would generate the same complaints as in the try block?

I want to be able to set result = once and only once.

So where do you set result = true; to get it to compile cleanly?

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记忆消瘦 2024-11-12 08:45:33

不设置变量要简单得多。

private boolean someMethod() {
    try {
        // do the logic here that might throw the following
        return true;

    } catch (IOException ioe) {
        // handle IOE
    } catch (ClassNotFoundException cnfe) {
        // handle CNFE
    }
    return false;
}

It's a lot simpler to not set a variable.

private boolean someMethod() {
    try {
        // do the logic here that might throw the following
        return true;

    } catch (IOException ioe) {
        // handle IOE
    } catch (ClassNotFoundException cnfe) {
        // handle CNFE
    }
    return false;
}

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安稳善良 2024-11-12 08:45:33

尝试使用final来强制“只分配一次”总是很棘手的。您可以使用第二个变量：

private boolean someMethod()
{
    boolean res;
    try
    {
        // do the logic here that might throw the following
        // exceptions
    }
    catch (final IOException ioe)
    {
        res = false;
    }
    catch (final ClassNotFoundException cnfe)
    {
        res = false;
    }
    final boolean result = res;
    return result;
}

但真正的问题是，为什么不直接删除 final 限定符呢？

Trying to use final to enforce "assign exactly once" is always tricky. You can use a second variable:

private boolean someMethod()
{
    boolean res;
    try
    {
        // do the logic here that might throw the following
        // exceptions
    }
    catch (final IOException ioe)
    {
        res = false;
    }
    catch (final ClassNotFoundException cnfe)
    {
        res = false;
    }
    final boolean result = res;
    return result;
}

But the real question is, why not just remove the final qualifier?

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