blocks|key|881200|text|您可以使用setScale()将小数位数减少到零。假设value保存要四舍五入的值：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|881201|BigDecimal+scaled+=+value.setScale(0,+RoundingMode.HALF_UP);
System.out.println(value+%2B+"+->+"+%2B+scaled);|code-block|syntax|javascript|881202|使用round()稍微复杂一些，因为它需要您指定要保留的位数。在您的示例中，这将是3，但这并不是对所有值都有效：|881203|BigDecimal+rounded+=+value.round(new+MathContext(3,+RoundingMode.HALF_UP));
System.out.println(value+%2B+"+->+"+%2B+rounded);|881204|(请注意，BigDecimal对象是不可变的；setScale和round都将返回一个新对象。)|881205|entityMap^0|5|A|R|5|0|0|2|7|0|0|5|A|N|8|W|5|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|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|11|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|12|8|@$9|13|A|14|B|C]|$9|15|A|16|B|C]|$9|17|A|18|B|C]]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|19|8|@]|D|@]|E|$]]]|R|$]]

You can use <code>setScale()</code> to reduce the number of fractional digits to zero. Assuming <code>value</code> holds the value to be rounded:

<pre><code>BigDecimal scaled = value.setScale(0, RoundingMode.HALF_UP);
System.out.println(value + " -&gt; " + scaled);
</code></pre>

Using <code>round()</code> is a bit more involved as it requires you to specify the number of digits to be retained. In your examples this would be 3, but this is not valid for all values:

<pre><code>BigDecimal rounded = value.round(new MathContext(3, RoundingMode.HALF_UP));
System.out.println(value + " -&gt; " + rounded);
</code></pre>

(Note that <code>BigDecimal</code> objects are immutable; both <code>setScale</code> and <code>round</code> will return a new object.)

blocks|key|881352|text|我认为你不能用一条命令就把它整成这样。试一试|type|unstyled|depth|inlineStyleRanges|entityRanges|data|881353|++++ArrayList<BigDecimal>+list+=+new+ArrayList<BigDecimal>();
++++list.add(new+BigDecimal("100.12"));
++++list.add(new+BigDecimal("100.44"));
++++list.add(new+BigDecimal("100.50"));
++++list.add(new+BigDecimal("100.75"));

++++for+(BigDecimal+bd+:+list){
++++++++System.out.println(bd%2B"+->+"%2Bbd.setScale(0,RoundingMode.HALF_UP).setScale(2));
++++}

Output:
100.12+->+100.00
100.44+->+100.00
100.50+->+101.00
100.75+->+101.00|code-block|syntax|javascript|881354|我测试了其余的示例，它返回了所需的值，但我不能保证它的正确性。|881355|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|$]]

I don't think you can round it like that in a single command. Try 

<pre><code> ArrayList&lt;BigDecimal&gt; list = new ArrayList&lt;BigDecimal&gt;();
 list.add(new BigDecimal("100.12"));
 list.add(new BigDecimal("100.44"));
 list.add(new BigDecimal("100.50"));
 list.add(new BigDecimal("100.75"));

 for (BigDecimal bd : list){
 System.out.println(bd+" -&gt; "+bd.setScale(0,RoundingMode.HALF_UP).setScale(2));
 }

Output:
100.12 -&gt; 100.00
100.44 -&gt; 100.00
100.50 -&gt; 101.00
100.75 -&gt; 101.00
</code></pre>

I tested for the rest of your examples and it returns the wanted values, but I don't guarantee its correctness.

blocks|key|1096219|text|你想要的|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1096220|round(new+MathContext(0));++//+or+perhaps+another+math+context+with+rounding+mode+HALF_UP|code-block|syntax|javascript|1096221|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 want

<pre><code>round(new MathContext(0)); // or perhaps another math context with rounding mode HALF_UP
</code></pre>

blocks|key|1096338|text|简单地看一下：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1096339|http://download.oracle.com/javase/6/docs/api/java/math/BigDecimal.html#ROUND_HALF_UP|offset|length|1096340|和：|1096341|setScale(int+precision,+int+roundingMode)|code-block|syntax|javascript|1096342|或者如果使用Java+6，那么|1096343|http://download.oracle.com/javase/6/docs/api/java/math/RoundingMode.html#HALF_UP|1096344|http://download.oracle.com/javase/6/docs/api/java/math/MathContext.html|1096345|或者：|1096346|setScale(int+precision,+RoundingMode+mode);
round(MathContext+mc);|1096347|entityMap|0|LINK|mutability|MUTABLE|url|1|2^0|0|0|2C|0|0|0|0|0|0|28|1|0|0|1Z|2|0|0|0^^$0|@$1|2|3|4|5|6|7|15|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|16|8|@]|9|@$D|17|E|18|1|19]]|A|$]]|$1|F|3|G|5|6|7|1A|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|1B|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|1C|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|1D|8|@]|9|@$D|1E|E|1F|1|1G]]|A|$]]|$1|Q|3|R|5|6|7|1H|8|@]|9|@$D|1I|E|1J|1|1K]]|A|$]]|$1|S|3|T|5|6|7|1L|8|@]|9|@]|A|$]]|$1|U|3|V|5|J|7|1M|8|@]|9|@]|A|$K|L]]|$1|W|3|-4|5|6|7|1N|8|@]|9|@]|A|$]]]|X|$Y|$5|Z|10|11|A|$12|C]]|13|$5|Z|10|11|A|$12|P]]|14|$5|Z|10|11|A|$12|R]]]]

Simply look at: 

<a href="http://download.oracle.com/javase/6/docs/api/java/math/BigDecimal.html#ROUND_HALF_UP" rel="nofollow">http://download.oracle.com/javase/6/docs/api/java/math/BigDecimal.html#ROUND_HALF_UP</a>

and:

<pre><code>setScale(int precision, int roundingMode)
</code></pre>

Or if using Java 6, then

<a href="http://download.oracle.com/javase/6/docs/api/java/math/RoundingMode.html#HALF_UP" rel="nofollow">http://download.oracle.com/javase/6/docs/api/java/math/RoundingMode.html#HALF_UP</a>

<a href="http://download.oracle.com/javase/6/docs/api/java/math/MathContext.html" rel="nofollow">http://download.oracle.com/javase/6/docs/api/java/math/MathContext.html</a>

and either:

<pre><code>setScale(int precision, RoundingMode mode);
round(MathContext mc);
</code></pre>

blocks|key|1096468|text|如果我按照Grodriguez的回答|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1096469|System.out.println(""+%2B+value);
value+=+value.setScale(0,+BigDecimal.ROUND_HALF_UP);
System.out.println(""+%2B+value);|code-block|syntax|javascript|1096470|这是输出|1096471|100.23+->+100
100.77+->+101|1096472|这不是我想要的，所以我最终做了这件事..|1096473|System.out.println(""+%2B+value);
value+=+value.setScale(0,+BigDecimal.ROUND_HALF_UP);
value+=+value.setScale(2,+BigDecimal.ROUND_HALF_UP);
System.out.println(""+%2B+value);|1096474|这就是我所得到的|1096475|100.23+->+100.00
100.77+->+101.00|1096476|这解决了我现在的问题..：)谢谢大家。|1096477|entityMap^0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Y|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|10|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|11|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|12|8|@]|9|@]|A|$]]|$1|Q|3|R|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|S|3|T|5|6|7|14|8|@]|9|@]|A|$]]|$1|U|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|V|$]]

If i go by Grodriguez's answer 

<pre><code>System.out.println("" + value);
value = value.setScale(0, BigDecimal.ROUND_HALF_UP);
System.out.println("" + value);
</code></pre>

This is the output

<pre><code>100.23 -&gt; 100
100.77 -&gt; 101
</code></pre>

Which isn't quite what i want, so i ended up doing this..

<pre><code>System.out.println("" + value);
value = value.setScale(0, BigDecimal.ROUND_HALF_UP);
value = value.setScale(2, BigDecimal.ROUND_HALF_UP);
System.out.println("" + value);
</code></pre>

This is what i get

<pre><code>100.23 -&gt; 100.00
100.77 -&gt; 101.00
</code></pre>

This solves my problem for now .. : )
Thank you all.

I need the following results

<pre><code>100.12 -&gt; 100.00
100.44 -&gt; 100.00
100.50 -&gt; 101.00
100.75 -&gt; 101.00
</code></pre>

<code>.round()</code> or <code>.setScale()</code> ? How do I go about this?

Java BigDecimal: Round to the nearest whole value

我需要以下结果100.12 -> 100.00100.44 -> 100.00100.50 -> 101.00100.75 -> 101.00.round()还是.setScale()？我该怎么做呢？

问Java BigDecimal:舍入到最接近的整数值
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