blocks|key|836881|text|最简单的方法是将跳过的代码嵌入到if中，与您拥有的代码具有相反的意义。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|836882|请参阅http://www.scala-lang.org/node/257|836883|entityMap|0|LINK|mutability|MUTABLE|url|http://www.scala-lang.org/node/257^0|G|2|0|3|Y|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|S|8|@]|D|@$9|T|A|U|1|V]]|E|$]]|$1|H|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|I|$J|$5|K|L|M|E|$N|O]]]]

The simplest way is to embed the skipped-over code in an <code>if</code> with reversed-sense to what you have.

See <a href="http://www.scala-lang.org/node/257" rel="nofollow">http://www.scala-lang.org/node/257</a>

blocks|key|836963|text|通常，您可以在开始之前进行过滤，以避免出现这些情况：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|836964|val+goodStocks+=+allStocks.view.
++map(stock+=>+(stock,+stock.getQuote)).filter(_._2+!=+null).
++map+{+case+(stock,+quote)+=>+(stock,quote,+quote.getPrice)+}.filter(_._3+!=+null)|code-block|syntax|javascript|836965|(这个例子展示了如果你需要部分结果，你将如何携带它们)。我使用了一个视图，这样就可以根据需要计算结果，而不是在每个步骤中创建一堆新的集合。|836966|实际上，您可能有引号和这样的返回选项--在StackOverflow上查看有关如何使用这些选项而不是null返回值的示例。|836967|但是，无论如何，如果这类事情不能很好地工作(例如，因为您生成了太多需要保留的中间结果，或者您依赖于更新可变变量，并且希望保持计算模式的简单性，以便知道何时会发生什么)，并且您不能以不同的、可能更健壮的方式来构想问题，那么您可以|836968|import+scala.util.control.Breaks._
for+(stock+<-+allStocks)+{
++breakable+{
++++val+quote+=+getQuote(...)
++++if+(quoteLast+eq+null)+break;
++++...
++}
}|836969|breakable结构指定了中断应该带您到的位置。如果将breakable放在for循环之外，它的工作方式类似于标准Java风格的break。如果你把它放在里面，它的行为就像continue。|offset|length|style|CODE|836970|当然，如果条件数量非常少，则根本不需要continue；只需使用if语句的else即可。|836971|entityMap^0|0|0|0|0|0|0|0|9|2F|8|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|10|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|11|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|12|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|14|8|@$Q|15|R|16|S|T]|$Q|17|R|18|S|T]]|9|@]|A|$]]|$1|U|3|V|5|6|7|19|8|@]|9|@]|A|$]]|$1|W|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]]|X|$]]

Generally you try to avoid those situations to begin with by filtering before you even start:

<pre><code>val goodStocks = allStocks.view.
 map(stock =&gt; (stock, stock.getQuote)).filter(_._2 != null).
 map { case (stock, quote) =&gt; (stock,quote, quote.getPrice) }.filter(_._3 != null)
</code></pre>

(this example showing how you'd carry along partial results if you need them). I've used a view so that results will be computed as-needed, instead of creating a bunch of new collections at each step.

Actually, you'd probably have the quotes and such return options--look around on StackOverflow for examples of how to use those instead of null return values.

But, anyway, if that sort of thing doesn't work so well (e.g. because you are generating too many intermediate results that you need to keep, or you are relying on updating mutable variables and you want to keep the evaluation pattern simple so you know what's happening when) and you can't conceive of the problem in a different, possibly more robust way, then you can

<pre><code>import scala.util.control.Breaks._
for (stock &lt;- allStocks) {
 breakable {
 val quote = getQuote(...)
 if (quoteLast eq null) break;
 ...
 }
}
</code></pre>

The <code>breakable</code> construct specifies where breaks should take you to. If you put breakable outside a for loop, it works like a standard Java-style break. If you put it inside, it acts like <code>continue</code>.

Of course, if you have a very small number of conditions, you don't need the continue at all; just use the else of the if-statement.

blocks|key|837014|text|如果真正关注的是continue而不是null处理，那么只需定义一个内部方法(+null处理部分在scala中是另一种习惯用法)：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|837015|def+handleStock(stock:+String):+Unit+{
++val+quote+=+getQuote(...)
++if+(null+==+quoteLast)+{
++++return
++}

++val+price+=+quote.getPrice();
++if+(null+==+price)+{
++++return
++}
}

for+(stock+<-+allStocks)+{
++handleStock(stock)
}|code-block|syntax|javascript|837016|entityMap^0|8|8|J|4|14|4|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|U|8|@]|D|@]|E|$]]]|L|$]]

If the focus is really on the <code>continue</code> and not on the <code>null</code> handling, just define an inner method (the <code>null</code> handling part is a different idiom in scala):

<pre><code>def handleStock(stock: String): Unit {
 val quote = getQuote(...)
 if (null == quoteLast) {
 return
 }

 val price = quote.getPrice();
 if (null == price) {
 return
 }
}

for (stock &lt;- allStocks) {
 handleStock(stock)
}
</code></pre>

blocks|key|837077|text|在这里，您的控制结构可以非常地道地映射到下面的for循环中，并且您的代码演示了Scala的for循环所设计的那种过滤。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|837078|for+{stock+<-+allStocks.view
+++++quote+=+getQuote(...)
+++++if+quoteLast+!=+null
+++++price+=+quote.getPrice
+++++if+null+!=+price
++++}{
++++++//+whatever+comes+after+all+of+the+null+tests
++++}|code-block|syntax|javascript|837079|顺便说一句，Scala会自动将这段代码从Rex+Kerr的解决方案中去掉|837080|val+goodStocks+=+allStocks.view.
++map(stock+=>+(stock,+stock.getQuote)).filter(_._2+!=+null).
++map+{+case+(stock,+quote)+=>+(stock,quote,+quote.getPrice)+}.filter(_._3+!=+null)|837081|此解决方案可能不适用于可能使用continue的所有不同类型的更复杂的流，但它确实解决了许多常见的问题。|837082|entityMap^0|N|3|19|3|0|0|0|0|F|8|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|Y|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|Z|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|10|8|@$9|11|A|12|B|C]]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|13|8|@]|D|@]|E|$]]]|R|$]]

Your control structure here can be mapped very idiomatically into the following <code>for</code> loop, and your code demonstrates the kind of filtering that Scala's <code>for</code> loop was designed for.

<pre><code>for {stock &lt;- allStocks.view
 quote = getQuote(...)
 if quoteLast != null
 price = quote.getPrice
 if null != price
 }{
 // whatever comes after all of the null tests
 }
</code></pre>

By the way, Scala will automatically desugar this into the code from Rex Kerr's solution

<pre><code>val goodStocks = allStocks.view.
 map(stock =&gt; (stock, stock.getQuote)).filter(_._2 != null).
 map { case (stock, quote) =&gt; (stock,quote, quote.getPrice) }.filter(_._3 != null)
</code></pre>

This solution probably doesn't work in general for all different kinds of more complex flows that might use <code>continue</code>, but it does address a lot of common ones.

blocks|key|621237|text|在这样的情况下，你不需要continue或trick或任何类似的东西:+Options和for+comprehensions做得很好，|type|unstyled|depth|inlineStyleRanges|entityRanges|data|621238|val+stocksWithPrices+=
++for+{
++++stock+<-+allStocks
++++quote+<-+Option(getQuote(...))
++++price+<-+Option(quote.getPrice())
++}+yield+(stock,+quote,+price);|code-block|syntax|javascript|621239|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|$]]

You don't need continue or breakable or anything like that in cases like this: Options and for comprehensions do the trick very nicely,

<pre><code>val stocksWithPrices =
 for {
 stock &lt;- allStocks
 quote &lt;- Option(getQuote(...))
 price &lt;- Option(quote.getPrice())
 } yield (stock, quote, price);
</code></pre>

<pre><code>for (String stock : allStocks) {

 Quote quote = getQuote(...);
 if (null == quoteLast) {
 continue;
 }

 Price price = quote.getPrice();
 if (null == price) {
 continue;
 }

}
</code></pre>

I don't necessarily need a line by line translation, but I'm looking for the "Scala way" to handle this type of problem.

How does the following Java "continue" code translate to Scala?

Java

for (String stock : allStocks) {    Quote quote = getQuote(...);    if (null == quoteLast) {        continue;    }    Price price = quote.getPrice();    if (nul...

问下面的Java "continue“代码如何转换为Scala？
EN

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问下面的Java "continue“代码如何转换为Scala？
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