Posted on 2007-11-30 17:47
蜀山兆孨龘 閱讀(1116)
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| JDK 源代碼中的搞笑之處 |
Funny Things in JDK Source |
| 雖然完整版的 JDK 源代碼現已開放了，但安裝在 Java\jdk[版本號] 目錄下的公共 src.zip 仍然是我最經常參考的資源。每次我遇到一個 API 問題，都會刊這個公共源代碼。解決問題之余，我還找到很多有趣的東西，有時還搞笑。這里距三個例子。 |
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. |
| 大概從 JDK 5.0 開始，類 java.lang.Object 引入了一個叫 wait(long timeout, int nanos) 的方法。等等，nanos，納秒？眾所周知，即使在強大的 Windows 多媒體 API 里面，計時器的精度也只有一毫秒，也就是一兆納秒。盡管 Java 非常棒，但不能處理納秒。而源代碼證明了這一點，納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... |
| 今天我想得到一個 JDialog 的所有者，但卻沒有 getOwner() 方法。最后我才明白 JDialog 的所有者就是它的父組件，用 getParent() 就可以了。那現在所有者等同于父級了？ |
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 的實現有錯。一些安裝在 JSpinner 上的偵聽器絲毫不起作用。我在 JSpinner.java 里找到這段注釋：“還是不對，我們沒其他辦法了，SpinnerModel 和 JFormattedTextField 現已不同步了。”JDK 的開發者的誠實值得感謝。我的解決方法是直接操控復合式組件 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. |