blocks|key|2650193|text|注意，如果下一个令牌不是整数，Scanner.nextInt也会抛出InputMismatchException。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2650194|从docs|2650195|2650196|抛出:+InputMismatchException+-如果下一个标记与整数正则表达式不匹配，或超出范围|blockquote|2650197|2650198|2650199|InputMismatchException是一个RuntimeException，因此可以在try/catch块中忽略它，但您也可以显式地处理它：|2650200|try
{
++++//+...+Scanner.nextInt
}
catch+(FileNotFoundException+e)
{
++++System.out.println("File+not+found!");
++++System.exit(1);
}
catch+(InputMismatchException+e)
{
++++//+...+not+an+int
}|code-block|syntax|javascript|2650201|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/6/docs/api/java/util/Scanner.html#nextInt%2528%2529^0|F|F|Y|M|0|1|4|0|0|0|0|0|0|0|M|P|G|1B|9|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@$9|13|A|14|B|C]|$9|15|A|16|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|17|8|@]|D|@$9|18|A|19|1|1A]]|E|$]]|$1|H|3|-4|5|6|7|1B|8|@]|D|@]|E|$]]|$1|I|3|J|5|K|7|1C|8|@]|D|@]|E|$]]|$1|L|3|-4|5|6|7|1D|8|@]|D|@]|E|$]]|$1|M|3|-4|5|6|7|1E|8|@]|D|@]|E|$]]|$1|N|3|O|5|6|7|1F|8|@$9|1G|A|1H|B|C]|$9|1I|A|1J|B|C]|$9|1K|A|1L|B|C]]|D|@]|E|$]]|$1|P|3|Q|5|R|7|1M|8|@]|D|@]|E|$S|T]]|$1|U|3|-4|5|6|7|1N|8|@]|D|@]|E|$]]]|V|$W|$5|X|Y|Z|E|$10|11]]]]

Note that <code>Scanner.nextInt</code> also throws an <code>InputMismatchException</code> if the next token isn't an integer.

From the <a href="http://docs.oracle.com/javase/6/docs/api/java/util/Scanner.html#nextInt%28%29" rel="nofollow">docs</a>:

<blockquote>
 Throws:
 InputMismatchException - if the next token does not match the Integer regular expression, or is out of range
</blockquote>

<code>InputMismatchException</code> is a <code>RuntimeException</code>, and so can be ignored in a <code>try/catch</code> block, but you can also explicitly handle it:

<pre><code>try
{
 // ... Scanner.nextInt
}
catch (FileNotFoundException e)
{
 System.out.println("File not found!");
 System.exit(1);
}
catch (InputMismatchException e)
{
 // ... not an int
}
</code></pre>

blocks|key|2641920|text|您在何处将数据从文件转换为整数？？您应该在那里添加一个try-catch。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2641921|而不是使用下面的while循环，在那里您必须捕获TypeMismatch的异常：-|2641922|++++while+(scFileData.hasNext())+{
++++++++try+{
++++++++++++sum+=+sum+%2B+scFileData.nextInt();
++++++++++++c%2B%2B;
++++++++}+catch+(InputMismatchException+e)+{
++++++++++++System.out.println("Invalid+Input");
++++++++}
++++}|code-block|syntax|javascript|2641923|您可以使用如下所示的变体：|2641924|++++while+(scFileData.hasNextInt())
++++{
++++++++sum+=+sum+%2B+scFileData.nextInt();
+++++++++c%2B%2B;
++++}|2641925|scanner.hasNextInt()将自动检查输入是否为整数。|offset|length|style|CODE|2641926|另外，当您在try-catch块外部声明变量时..我建议不要使用大的try-catch块..|2641927|相反，您可以将file+reading语句包含在try-catch中(这将是一个语句)。然后，在几个语句之后，您可以再次将您的scanner.nextInt()包含在另一个try-catch中。|2641928|所以，我会像这样修改你的代码：|2641929|public+class+NumAvg2+{

public+static+void+main(String[]+args)
{
++++int+c+=+1;++
++++long+sum+=+0;
++++String+strFileName;

++++strFileName+=+args[0];

++++Scanner+scFileData;

++++try{
++++++++scFileData+=+new+Scanner+(new+File(strFileName));

++++}+catch+(FileNotFoundException+e)+{
++++++++System.out.println("File+not+found!");
++++++++System.exit(1);
++++}
++++while+(true)+{
++++++++if+(scFileData.hasNextInt())
++++++++{
++++++++++++sum+=+sum+%2B+scFileData.nextInt();
++++++++++++c%2B%2B;
++++++++++++break;
++++++++}+else+{
++++++++++++System.out.println("Enter+an+integr");
++++++++}
++++}

++++scFileData.close();
++++System.out.println("Number+of+integers:+"+%2B+(c+-+1));+
++++System.out.println(+"Average+=+"+%2B+(float)sum/(c+-+1));

}
}|2641930|这样，您的代码就会变得更加整洁。*只是一个建议..|2641931|entityMap^0|0|0|0|0|0|0|K|0|0|7|C|1R|H|0|0|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|15|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|16|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|17|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|18|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|19|8|@$O|1A|P|1B|Q|R]]|9|@]|A|$]]|$1|S|3|T|5|6|7|1C|8|@]|9|@]|A|$]]|$1|U|3|V|5|6|7|1D|8|@$O|1E|P|1F|Q|R]|$O|1G|P|1H|Q|R]]|9|@]|A|$]]|$1|W|3|X|5|6|7|1I|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|F|7|1J|8|@]|9|@]|A|$G|H]]|$1|10|3|11|5|6|7|1K|8|@]|9|@]|A|$]]|$1|12|3|-4|5|6|7|1L|8|@]|9|@]|A|$]]]|13|$]]

Where are you converting your data from file to integer?? You should add one try-catch there..

Instead of using the below while loop, where you have to catch the exception for TypeMismatch: - 

<pre><code> while (scFileData.hasNext()) {
 try {
 sum = sum + scFileData.nextInt();
 c++;
 } catch (InputMismatchException e) {
 System.out.println("Invalid Input");
 }
 }
</code></pre>

You can use a variation like the one below: - 

<pre><code> while (scFileData.hasNextInt())
 {
 sum = sum + scFileData.nextInt();
 c++;
 }
</code></pre>

<code>scanner.hasNextInt()</code> will automatically check whether input in integer or not..

Also, as you are declaring your variable outside your try-catch block.. I would suggest not to use a big try-catch block..

Rather you can surround <code>file reading</code> statement around a try-catch (That would be one statement).. Then after a few statements, you can again surround your <code>scanner.nextInt()</code> around another try-catch..

So, I would modify your code like this: - 

<pre><code>public class NumAvg2 {

public static void main(String[] args)
{
 int c = 1; 
 long sum = 0;
 String strFileName;

 strFileName = args[0];

 Scanner scFileData;

 try{
 scFileData = new Scanner (new File(strFileName));

 } catch (FileNotFoundException e) {
 System.out.println("File not found!");
 System.exit(1);
 }
 while (true) {
 if (scFileData.hasNextInt())
 {
 sum = sum + scFileData.nextInt();
 c++;
 break;
 } else {
 System.out.println("Enter an integr");
 }
 }

 scFileData.close();
 System.out.println("Number of integers: " + (c - 1)); 
 System.out.println( "Average = " + (float)sum/(c - 1));

}
}
</code></pre>

This way your code becomes more cleaner.. * Just a Suggestion..

blocks|key|4053712|text|要捕获多个异常，您可以像这样链接它们：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4053713|public+class+NumAvg2+{

public+static+void+main(String[]+args)
{
int+c+=+1;++
long+sum+=+0;
String+strFileName;

strFileName+=+args[0];

Scanner+scFileData;
try{
++++scFileData+=+new+Scanner+(new+File(strFileName));

++++while+(scFileData.hasNext())
++++{
++++++++sum+=+sum+%2B+scFileData.nextInt();
++++++++c%2B%2B;
++++}

scFileData.close();
System.out.println("Number+of+integers:+"+%2B+(c+-+1));+
System.out.println(+"Average+=+"+%2B+(float)sum/(c+-+1));

}+catch+(FileNotFoundException+e)+{
++++System.out.println("File+not+found!");
++++System.exit(1);
}+catch(InputMismatchException+e){
++++//handle+it
}
}+
}|code-block|syntax|javascript|4053714|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|$]]

To catch multiple exceptions, you chain them like so:

<pre><code>public class NumAvg2 {

public static void main(String[] args)
{
int c = 1; 
long sum = 0;
String strFileName;

strFileName = args[0];

Scanner scFileData;
try{
 scFileData = new Scanner (new File(strFileName));

 while (scFileData.hasNext())
 {
 sum = sum + scFileData.nextInt();
 c++;
 }

scFileData.close();
System.out.println("Number of integers: " + (c - 1)); 
System.out.println( "Average = " + (float)sum/(c - 1));

} catch (FileNotFoundException e) {
 System.out.println("File not found!");
 System.exit(1);
} catch(InputMismatchException e){
 //handle it
}
} 
}
</code></pre>

blocks|key|2641961|text|...
}+catch+(FileNotFoundException+e)+{
++++System.out.println("File+not+found!");
++++System.exit(1);
}+catch+(InputMismatchException+e)+{
++++//+Add+stuff+into+your+new+exception+handling+block
}
...|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|2641962|您的集成开发环境可能没有抱怨过这一点，因为InputMismatchException是一个RuntimeException+(未检查的异常)，而FileNotFoundException是一个常规的检查异常。|unstyled|2641963|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>...
} catch (FileNotFoundException e) {
 System.out.println("File not found!");
 System.exit(1);
} catch (InputMismatchException e) {
 // Add stuff into your new exception handling block
}
...
</code></pre>

Your IDE may have not complained about this because InputMismatchException is a RuntimeException (unchecked exception), while FileNotFoundException is a regular checked Exception.

blocks|key|4053731|text|}+catch+(FileNotFoundException+%7C+InputMismatchException+e)+{
++++e.printStackTrace();
++++System.exit(1);
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|4053732|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>} catch (FileNotFoundException | InputMismatchException e) {
 e.printStackTrace();
 System.exit(1);
}
</code></pre>

blocks|key|730137|text|如果您愿意，可以使用Java7的multi+catch|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|730138|try+{
...
}
catch+(FileNotFoundException%7CInputMismatchException+ex)+{
//deal+with+exception
}|code-block|syntax|javascript|730139|这比多个捕获要干净一些。如果抛出这两个异常中的任何一个，都会在单个catch块中捕获它|730140|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/7/docs/technotes/guides/language/catch-multiple.html^0|G|B|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]]|C|$]]|$1|D|3|E|5|F|7|W|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|X|8|@]|9|@]|C|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]]]

You can use Java 7's <a href="http://docs.oracle.com/javase/7/docs/technotes/guides/language/catch-multiple.html" rel="noreferrer">multi catch</a> if you want

<pre><code>try {
...
}
catch (FileNotFoundException|InputMismatchException ex) {
//deal with exception
}
</code></pre>

This is a bit cleaner than multiple catches. If either of these exceptions is thrown it is caught in the single catch block

blocks|key|273580|text|}+catch+(InputMismatchException+e)+{
++++System.out.println("Not+integer!");
++++System.exit(1);
}+catch+(FileNotFoundException+e)+{
++++System.out.println("File+not+found!");
++++System.exit(1);
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|273581|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>} catch (InputMismatchException e) {
 System.out.println("Not integer!");
 System.exit(1);
} catch (FileNotFoundException e) {
 System.out.println("File not found!");
 System.exit(1);
}
</code></pre>

The following code calculates the average of numbers that are stored in a text file.
I have added some exception handling for "file not found" errors. I need to know how to add another exception for when the data in the text file is not numeric (or not int). I thought about adding multiple catches. Not sure how though?

<pre><code>import java.util.*;
import java.io.*;

public class NumAvg2 {

 public static void main(String[] args)
 {
 int c = 1; 
 long sum = 0;
 String strFileName;

 strFileName = args[0];

 Scanner scFileData;
 try{
 scFileData = new Scanner (new File(strFileName));

 while (scFileData.hasNext())
 {
 sum = sum + scFileData.nextInt();
 c++;
 }

 scFileData.close();
 System.out.println("Number of integers: " + (c - 1)); 
 System.out.println( "Average = " + (float)sum/(c - 1));

 } catch (FileNotFoundException e) {
 System.out.println("File not found!");
 System.exit(1);
 }

 } 
} 
</code></pre>

Java Exception Handling?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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下面的代码计算存储在文本文件中的数字的平均值。我为“找不到文件”错误添加了一些异常处理。当文本文件中的数据不是数字(或整型)时，我需要知道如何添加另一个异常。我考虑添加多个捕获物。但是不确定是怎么做到的？import java.util.*;import java.io.*;public class NumAvg2 {...

问Java异常处理？
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