Long.getLong() 失败，返回 null 到有效字符串

问题描述

过去两个小时我一直在调试看似极不可能的事情.我已经将辅助 Android Activity 的方法剥离为:

I've spent the past two hours debugging what seems extremely unlikely. I've stripped the method of a secondary Android Activity to exactly this:

public void onClick(View v) {
        String str = "25";
        long my_long = Long.getLong(str);
} // onClick (v)

是的，我遇到了一个很好的 NullPointerException:

And yeah, I get a crash with the good ol' NullPointerException:

09-11 02:02:50.444:错误/AndroidRuntime(1588):未捕获的处理程序:线程主因未捕获的异常而退出09-11 02:02:50.464:错误/AndroidRuntime(1588):java.lang.NullPointerException

09-11 02:02:50.444: ERROR/AndroidRuntime(1588): Uncaught handler: thread main exiting due to uncaught exception09-11 02:02:50.464: ERROR/AndroidRuntime(1588): java.lang.NullPointerException

看起来(从其他测试中)Long.getLong(str) 返回 NULL，这让我很抓狂.我错过了什么?

It looks like (from other tests) that Long.getLong(str) returns NULL, which is driving me bonkers. WHAT AM I MISSING?

提前致谢.我可以愚蠢地错过明显的东西，但我的理智很危险.

Thanks in advance. I'm okay with stupidly missing the obvious, but my sanity is on the line.

推荐答案

您忽略了一个事实，即 Long.getLong(String str) 不应该将 String 解析为 long，而是返回由该字符串表示的系统属性 的长值.正如其他人所建议的，您实际需要的是 Long.parseLong(String str).

You are missing the fact that Long.getLong(String str) is not supposed to parse a String to a long, but rather to return a long value of a system property represented by that string. As others have suggested, what you actually need is Long.parseLong(String str).

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