Posted on 2007-11-30 17:47
蜀山兆孨龘 阅读(1093)
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| JDK 源代码中的搞笑之处 |
Funny Things in JDK Source |
| 虽然完整版的 JDK 源代码现已开放了，但安装在 Java\jdk[版本号] 目录下的公共 src.zip 仍然是我最经常参考的资源。每次我遇到一个 API 问题，都会刊这个公共源代码。解决问题之余，我还找到很多有趣的东西，有时还搞笑。这里距三个例子。 |
Though the full version of JDK source is available now, but the public src.zip installed under Java\jdk[version_number] directory is still my most frequent refered resource. Every time I encounter an API problem, this public source is read. And besides solving those problems, I've also found many interesting things which are sometimes also funny. Here are three exaples. |
| 大概从 JDK 5.0 开始，类 java.lang.Object 引入了一个叫 wait(long timeout, int nanos) 的方法。等等，nanos，纳秒？众所周知，即使在强大的 Windows 多媒体 API 里面，计时器的精度也只有一毫秒，也就是一兆纳秒。尽管 Java 非常棒，但不能处理纳秒。而源代码证明了这一点，纳秒被舍入到最接近的毫秒，0 或 1……精彩…… |
Maybe since JDK 5.0, a method called wait(long timeout, int nanos)is introduced into Class java.lang.Object.Object. Wait a minute, nanos, is it nanoseconds? It's no secret thst even in powerful Windows multimedia API, the precision of timer is only one millisecond, that is a million nanosecond. Though Java is pretty great, it can not deal with nanoseconds. And the source proves it, that nanoseconds are rounded to the nearest millisecond, 0 or 1... Amazing... |
| 今天我想得到一个 JDialog 的所有者，但却没有 getOwner() 方法。最后我才明白 JDialog 的所有者就是它的父组件，用 getParent() 就可以了。那现在所有者等同于父级了？ |
Today I wanted to get a JDialog's owner, but there's no method called getOwner(). Finally I was awear that the owner of a JDialog is exactly its parent component, and just using getParent() is okey. So owner is synonymous with parent now? |
| 最后，我想提下 JSpinner 的实现有错。一些安装在 JSpinner 上的侦听器丝毫不起作用。我在 JSpinner.java 里找到这段注释：“还是不对，我们没其他办法了，SpinnerModel 和 JFormattedTextField 现已不同步了。”JDK 的开发者的诚实值得感谢。我的解决方法是直接操控复合式组件 JSpinner 中的 JFormattedTextField。 |
At last, I wanna mention the JSpinner implementation is bugged. Some kinds of listener installed on a JSpinner take no effect at all. I found this comment in JSpinner.java: "Still bogus, nothing else we can do, the SpinnerModel and JFormattedTextField are now out of sync." The JDK developers deserve a thank for honesty. My solution is to directly manipulate the JFormattedTextField within JSpinner, a compound JComponent. |