blocks|key|1722932|text|我会跳过有趣的留言。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1722933|顺便说一句:我遇到过这样的情况，一段代码(在一个小的库中)只是假设一个编码是可用的。只是它被部署在一个有限的设备上，并在运行时爆炸。|1722934|检查异常用于显示代码中我们应该暂停一秒钟的地方，并考虑较少经过的路径(如“我的应用程序在网络崩溃时会做什么”和其他转折点情况)。将它们包装在IllegalStateException中并重新抛出是一种签署的合同，程序员说：“是的，考虑到所有风险，我对这里的位置承担全部责任”。如果不是因为检查异常，我们就无法从缺乏思考的情况下知道一个明智的决定。|1722935|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

I would skip the funny message.

BTW: I had a case where a piece of code (in a small library) just assumed that an encoding would be available. Only it got deployed on a limited device and exploded at runtime.

Checked exceptions serve to show places in our code where we should pause for a second and consider the paths less traveled (as in "what my app does when network dies" and other corner cases). Wrapping them in IllegalStateException and rethrowing is a sort of a signed contract, where the programmer says: "yes, all risks considered I take full responsibility for the spot right here". If it wasn't for checked exceptions, we would hava no way of knowing a consious decision from a plain lack of thought.

blocks|key|1723027|text|以下是我的解决方案--为Android开发的，但可以很容易地改编为“常规”Java：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1723028|public+class+ImpossibleException+extends+RuntimeException+{
++++public+ImpossibleException(@NonNull+String+whyNotPossible)+{
++++++++this(whyNotPossible,+null);
++++}

++++public+ImpossibleException(@NonNull+String+whyNotPossible,+Throwable+throwable)+{
++++++++super("Impossible+exception:+"+%2B+whyNotPossible,+throwable);
++++++++Log.e("Impossible",+whyNotPossible,+throwable);
++++}
}|code-block|syntax|javascript|1723029|用法：|1723030|try+{
++++byte[]+data+=+"Hello".getBytes("utf-8");
++++Log.i("Test",+"data.length="+%2B+data.length);
}+catch+(UnsupportedEncodingException+e)+{
++++throw+new+ImpossibleException("Android+always+supports+utf-8",+e);
}|1723031|whyNotPossible构造函数意味着不需要在发生错误的地方记录错误，也不需要注释。|offset|length|style|CODE|1723032|我猜这是一个口味问题，如果这应该是一个ImpossibleException+extends+RuntimeException或ImpossibleError+extends+Error。|1723033|entityMap^0|0|0|0|0|0|E|0|J|18|1S|T|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|Y|8|@$M|Z|N|10|O|P]]|9|@]|A|$]]|$1|Q|3|R|5|6|7|11|8|@$M|12|N|13|O|P]|$M|14|N|15|O|P]]|9|@]|A|$]]|$1|S|3|-4|5|6|7|16|8|@]|9|@]|A|$]]]|T|$]]

Here's my solution -- developed for Android but can be easily adapted for "regular" Java:

<pre><code>public class ImpossibleException extends RuntimeException {
 public ImpossibleException(@NonNull String whyNotPossible) {
 this(whyNotPossible, null);
 }

 public ImpossibleException(@NonNull String whyNotPossible, Throwable throwable) {
 super("Impossible exception: " + whyNotPossible, throwable);
 Log.e("Impossible", whyNotPossible, throwable);
 }
}
</code></pre>

Usage: 

<pre><code>try {
 byte[] data = "Hello".getBytes("utf-8");
 Log.i("Test", "data.length=" + data.length);
} catch (UnsupportedEncodingException e) {
 throw new ImpossibleException("Android always supports utf-8", e);
}
</code></pre>

The <code>whyNotPossible</code> constructor means there's no need to log the error where it happens, and there's also no need for a comment.

I guess it's a matter of taste if this should be an <code>ImpossibleException extends RuntimeException</code> or an <code>ImpossibleError extends Error</code>.

blocks|key|1723061|text|如果你在你的项目中使用Lombok，你可以用@SneakyThrows注释周围的方法，这类方法在RuntimeException中隐藏了检查过的异常(因此不需要用try-catch包围，也不需要在throws子句中声明它)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1723062|例如：|1723063|@SneakyThrows(URISyntaxException.class)
public+void+methodWithURL(URL+url){+//+No+throws+here
++++URI+uri+=+new+URI(url);+//+Assume+no+invalud+URI+syntax+possible
}|code-block|syntax|javascript|1723064|entityMap|0|LINK|mutability|MUTABLE|url|https://projectlombok.org/|1|https://projectlombok.org/features/SneakyThrows^0|M|D|1C|G|29|9|2Q|6|B|6|0|M|D|1|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]|$9|11|A|12|B|C]|$9|13|A|14|B|C]]|D|@$9|15|A|16|1|17]|$9|18|A|19|1|1A]]|E|$]]|$1|F|3|G|5|6|7|1B|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|1C|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|1D|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]|U|$5|P|Q|R|E|$S|V]]]]

If you use <a href="https://projectlombok.org/" rel="nofollow noreferrer">Lombok</a> in your project, you can annotate the surrounding method with <a href="https://projectlombok.org/features/SneakyThrows" rel="nofollow noreferrer"><code>@SneakyThrows</code></a> which kind of hides checked exceptions in <code>RuntimeException</code> (thus no need to surround by <code>try-catch</code> nor declare it in <code>throws</code> clause).
For instance:
<pre class="lang-java prettyprint-override"><code>@SneakyThrows(URISyntaxException.class)
public void methodWithURL(URL url){ // No throws here
 URI uri = new URI(url); // Assume no invalud URI syntax possible
}
</code></pre>

Sometimes, I'll end up having to catch an exception that I know can never happen, such as here

<pre><code>URLDecoder.decode("some string", "UTF-8"); //No unknown encoding possible
</code></pre>

or here:

<pre><code>public void methodWithURL(URL url){
 URI uri = new URI(url); //No invalud URI syntax possible
}
</code></pre>

How do you handle this? I generally log a funny error regarding how the laws of the universe have changed, and then throw a <code>RuntimeException</code>. Is there a better way?

How do you handle "impossible" exceptions in Java?

Android

Java

有时，我最终不得不捕获一个我知道永远不会发生的异常，比如这里URLDecoder.decode("some string", "UTF-8"); //No unknown encoding possible或者在这里：public void methodWithURL(URL url){    URI uri = ne...

问在Java中如何处理“不可能”的异常？
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