blocks|key|494814|text|异常是与任何其他类类似的类，只是它是从Exception扩展而来的。因此，如果您创建自己的类|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|494815|public+class+MyCustomException+extends+Exception|code-block|syntax|javascript|494816|您可以使用以下命令抛出这样的实例|494817|+++throw+new+MyCustomException(+...+);
+++//using+whatever+constructor+params+you+decide+to+use|494818|而this可能是一个有趣的读物|494819|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/6/docs/api/java/lang/Exception.html|1|http://www.javaworld.com/javaworld/jw-07-1998/jw-07-exceptions.html^0|J|9|J|9|0|0|0|0|0|1|4|1|0^^$0|@$1|2|3|4|5|6|7|10|8|@$9|11|A|12|B|C]]|D|@$9|13|A|14|1|15]]|E|$]]|$1|F|3|G|5|H|7|16|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|17|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|18|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|19|8|@]|D|@$9|1A|A|1B|1|1C]]|E|$]]|$1|Q|3|-4|5|6|7|1D|8|@]|D|@]|E|$]]]|R|$S|$5|T|U|V|E|$W|X]]|Y|$5|T|U|V|E|$W|Z]]]]

An exception is a class like any other class, except that it extends from <a href="http://docs.oracle.com/javase/6/docs/api/java/lang/Exception.html" rel="noreferrer"><code>Exception</code></a>. So if you create your own class

<pre><code>public class MyCustomException extends Exception
</code></pre>

you can throw such an instance with

<pre><code> throw new MyCustomException( ... );
 //using whatever constructor params you decide to use
</code></pre>

And <a href="http://www.javaworld.com/javaworld/jw-07-1998/jw-07-exceptions.html" rel="noreferrer">this</a> might be an interesting read

blocks|key|710438|text|您必须在其他地方将异常定义为一个新类|type|unstyled|depth|inlineStyleRanges|entityRanges|data|710439|public+class+YourCustomException+extends+Exception{

//Required+inherited+methods+here
}|code-block|syntax|javascript|710440|然后你可以随心所欲地抛出和接住YourCustomException。|710441|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

You have to define your exception elsewhere as a new class

<pre><code>public class YourCustomException extends Exception{

//Required inherited methods here
}
</code></pre>

Then you can throw and catch YourCustomException as much as you'd like.

blocks|key|494922|text|因为您可以只创建和抛出异常，所以可以像这样简单|type|unstyled|depth|inlineStyleRanges|entityRanges|data|494923|if+(+word.contains("+")+)
{
+++++throw+new+RuntimeException+(+"Word+contains+one+or+more+spaces"+)+;
}|code-block|syntax|javascript|494924|如果您想要更正式，可以创建一个异常类|494925|class+SpaceyWordException+extends+RuntimeException
{

}|494926|无论哪种方式，如果您使用RuntimeException，您的新Exception都将被取消选中。|offset|length|style|CODE|494927|entityMap^0|0|0|0|0|C|G|W|9|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|W|8|@$M|X|N|Y|O|P]|$M|Z|N|10|O|P]]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|R|$]]

Since you can just create and throw exceptions it could be as easy as

<pre><code>if ( word.contains(" ") )
{
 throw new RuntimeException ( "Word contains one or more spaces" ) ;
}
</code></pre>

If you would like to be more formal, you can create an Exception class

<pre><code>class SpaceyWordException extends RuntimeException
{

}
</code></pre>

Either way, if you use <code>RuntimeException</code>, your new <code>Exception</code> will be unchecked.

blocks|key|710558|text|您只需要创建一个扩展Exception+(用于检查的异常)或Exception的任何子类，或RuntimeException+(用于运行时异常)或RuntimeException的任何子类的类。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|710559|然后，在您的代码中只需使用|710560|if+(word.contains("+"))
++++throw+new+MyException("some+message");
}|code-block|syntax|javascript|710561|阅读Java教程。这是每个Java开发人员都应该知道的基本知识：http://docs.oracle.com/javase/tutorial/essential/exceptions/|offset|length|710562|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/tutorial/essential/exceptions/^0|0|0|0|W|1O|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|W|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|X|8|@]|9|@$K|Y|L|Z|1|10]]|A|$]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|T]]]]

You just need to create a class which extends Exception (for a checked exception) or any subclass of Exception, or RuntimeException (for a runtime exception) or any subclass of RuntimeException.

Then, in your code, just use 

<pre><code>if (word.contains(" "))
 throw new MyException("some message");
}
</code></pre>

Read the Java tutorial. This is basic stuff that every Java developer should know: <a href="http://docs.oracle.com/javase/tutorial/essential/exceptions/" rel="nofollow">http://docs.oracle.com/javase/tutorial/essential/exceptions/</a>

blocks|key|710595|text|您可以通过继承java.lang.Exception来创建自己的异常。Here就是一个可以帮助您做到这一点的示例。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|710596|entityMap|0|LINK|mutability|MUTABLE|url|http://www.seasite.niu.edu/cs580java/testexception.htm^0|7|J|Z|4|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]]|D|@$9|Q|A|R|1|S]]|E|$]]|$1|F|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]]]

You can create you own exception by inheriting from <code>java.lang.Exception</code> 
<a href="http://www.seasite.niu.edu/cs580java/testexception.htm" rel="nofollow">Here</a> is an example that can help you do that.

blocks|key|710669|text|关于创建自定义异常类的很好的答案。如果您打算重用有问题的异常，那么我将遵循他们的回答/建议。但是，如果您只需要抛出一个带有消息的快速异常，则可以就地使用基异常类。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|710670|String+word=reader.readLine();

if(word.contains("+"))
++/*create+custom+exeception*/
++throw+new+Exception("My+one+time+exception+with+some+message!");
}|code-block|syntax|javascript|710671|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Great answers about creating custom exception classes. If you intend to reuse the exception in question then I would follow their answers/advice. However, If you only need a quick exception thrown with a message then you can use the base exception class on the spot

<pre><code>String word=reader.readLine();

if(word.contains(" "))
 /*create custom exeception*/
 throw new Exception("My one time exception with some message!");
}
</code></pre>

blocks|key|495145|text|作为一个细心的程序员，经常会在特殊情况下抛出异常，值得一提的是一些通用的异常，如IllegalArgumentException、IllegalStateException和UnsupportedOperationException。IllegalArgumentException是我的最爱：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|495146|throw+new+IllegalArgumentException("Word+contains+blank:+"+%2B+word);|code-block|syntax|javascript|495147|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.oracle.com/javase/8/docs/api/index.html?java/lang/IllegalStateException.html^0|14|O|1T|L|2F|T|39|O|1T|L|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@$9|11|A|12|1|13]]|E|$]]|$1|F|3|G|5|H|7|14|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|15|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

As a careful programmer will often throw an exception for a special occurrence, it worth mentioning some general purpose exceptions like <code>IllegalArgumentException</code> and <a href="https://docs.oracle.com/javase/8/docs/api/index.html?java/lang/IllegalStateException.html" rel="noreferrer"><code>IllegalStateException</code></a> and <code>UnsupportedOperationException</code>. <code>IllegalArgumentException</code> is my favorite:

<pre><code>throw new IllegalArgumentException("Word contains blank: " + word);
</code></pre>

I would like to create a custom exception in Java, how do I do it?

<pre><code>...

try{

...

String word=reader.readLine();

if(word.contains(" "))
 /*create custom exception*/

}
catch(){
</code></pre>

When I create my custom exception with <code>throw new...</code>, I obtain the error <code>unreported exception...must be caught or declared to be thrown</code>

How to create a custom exception type in Java?

Java

我想在Java中创建一个自定义异常，我该怎么做？...try{...String word=reader.readLine();if(word.contains(" "))  /*create custom exception*/}catch(){当我使用throw new...创建自定义异常时，我获得了错误unrep...

问如何在Java中创建自定义异常类型？
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