blocks|key|1995097|text|不，Java没有内置这些。这是有原因的。使用可变类型是危险的，因为它们很容易被滥用。此外，它真的很容易实现。例如，commons-lang有一个MutableInt。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1995098|entityMap|0|LINK|mutability|MUTABLE|url|https://commons.apache.org/proper/commons-lang/apidocs/org/apache/commons/lang3/mutable/MutableInt.html^0|20|A|20|A|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]]]]

No, Java doesn't have these built in. And that is for a reason. Using mutable types is dangerous, as they can easily be misused. Additionally, it is really easy to implement it. For example, commons-lang has a <a href="https://commons.apache.org/proper/commons-lang/apidocs/org/apache/commons/lang3/mutable/MutableInt.html" rel="noreferrer"><code>MutableInt</code></a>.

blocks|key|1781342|text|如果包含可变包装器类的代码过于繁琐，则始终可以将值包装在int[]+mutable+=+{1};这样的数组中。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1781343|entityMap^0|S|K|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

You could always wrap the value in an array like <code>int[] mutable = {1};</code> if including the code for a mutable wrapper class is too cumbersome.

blocks|key|1995128|text|自从JDK1.5java现在有了java.util.concurrent.atomic.AtomicInteger|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1995129|这是一个线程安全的可变整数，使用示例：|1995130|final+AtomicInteger+value+=+new+AtomicInteger(0);|code-block|syntax|javascript|1995131|然后在后面：|1995132|value.incrementAndGet();|1995133|entityMap^0|G|15|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|V|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|W|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|X|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|Y|8|@]|D|@]|E|$K|L]]|$1|Q|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|R|$]]

Since JDK 1.5 java now has <code>java.util.concurrent.atomic.AtomicInteger</code>

This is a thread safe mutable integer, example of use:

<pre><code>final AtomicInteger value = new AtomicInteger(0);
</code></pre>

then later on:

<pre><code>value.incrementAndGet();
</code></pre>

blocks|key|1995169|text|下面是我为可变整数创建的一个小类：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1995170|public+class+MutableInteger+{
++++private+int+value;
++++public+MutableInteger(int+value)+{
++++++++this.value+=+value;
++++}
++++public+void+set(int+value)+{
++++++++this.value+=+value;
++++}
++++public+int+intValue()+{
++++++++return+value;
++++}
}|code-block|syntax|javascript|1995171|您可以很容易地将其扩展到任何其他原语。当然，就像其他人说的那样，你应该谨慎使用它。|1995172|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|$]]

Here's a small class I made for a mutable integer:

<pre><code>public class MutableInteger {
 private int value;
 public MutableInteger(int value) {
 this.value = value;
 }
 public void set(int value) {
 this.value = value;
 }
 public int intValue() {
 return value;
 }
}
</code></pre>

You could easily extend this to any other primitive. Of course, like everyone else is saying, you should use it carefully.

blocks|key|1781376|text|正如@Alexandre建议的那样，你可以使用nnnn[]作为任何原始类型的可变对象，java也有AtomicInteger和AtomicLong。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1781377|IMHO+int通常是比Integer更好的选择，而且它是可变的。|1781378|你能更详细地解释为什么你需要多个对象吗，也许还有另一种方法来实现同样的事情。|1781379|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|$]]

You can use an nnnn[] as a mutable object for any primitive type as @Alexandre suggests, java also has AtomicInteger and AtomicLong.

IMHO int is usually a better choice than Integer and that is mutable.

Can you more details of why you need a mutliple object, perhaps there is another way to achieve the same thing.

blocks|key|1781714|text|AtomicInteger已经提到过了。可以用AtomicReference<Double>模拟可变的Double。前面提到的警告是适用的，这是一种糟糕的风格，但有时您的代码如下所示|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1781715|double+sum=0
for+(Data+data:someListGenerator())
++sum%2B=data.getValue()|code-block|syntax|javascript|1781716|并希望将其重构为函数式Java+8风格。如果代码遵循此模式，但增加了相当大的复杂性，则最合理的转换可能是|1781717|AtomicReference<Double>+sumref=new+AtomicReference<>(0d);
someStreamGenerator().forEach(data->
++sumref.set(sumref.get().doubleValue()%2Bdata.getValue()));
double+sum=sumref.get().doubleValue();|1781718|当然，这至少是有问题的风格。这使得将代码转换成适当的函数风格变得非常困难。|1781719|entityMap^0|0|D|N|N|1F|6|0|0|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]|$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|Z|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|10|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|11|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|12|8|@]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|13|8|@]|D|@]|E|$]]]|R|$]]

<code>AtomicInteger</code> has already been mentioned. Mutable <code>Double</code>s can be emulated with <code>AtomicReference&lt;Double&gt;</code>. The already mentioned warnings apply and it is bad style, but sometimes you have code like this

<pre><code>double sum=0
for (Data data:someListGenerator())
 sum+=data.getValue()
</code></pre>

and want to refactor it in functional Java 8 style. If the code follows this pattern but adds considerable complexity to it, the most sensible conversion could be

<pre><code>AtomicReference&lt;Double&gt; sumref=new AtomicReference&lt;&gt;(0d);
someStreamGenerator().forEach(data-&gt;
 sumref.set(sumref.get().doubleValue()+data.getValue()));
double sum=sumref.get().doubleValue();
</code></pre>

Of course, this is at least questionable style. But I found myself more than once in a situation with a twisted loop over a <code>ResultSet</code> computing and partly cumulating three different information from it. This makes it really hard to convert the code into proper functional style. Converting the cumulating parts according to the above pattern seemed to me a reasonable tradeoff between clean code and oversimplified refactoring.

blocks|key|1781435|text|您可以导入Holder包(或者只导入您需要的类)，并且可以在其中使用org.omg.CORBA类。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1781436|例如，它有"IntHolder“，其中存储整数的字段是公共的，允许修改它。|1781437|public+static+void+triple(IntHolder+x){
++++x.value+=+3+*+x.value;
}

IntHolder+mutableInt+=+new+IntHolder(10);
triple(mutableInt);+++++
System.out.println(mutableInt.value);|code-block|syntax|javascript|1781438|它还有"LongHolder“和"DoubleHolder”，还有很多其他的你可以用的。请谨慎使用。|1781439|下面是它的接口：https://docs.oracle.com/javase/7/docs/api/org/omg/CORBA/package-summary.html|offset|length|1781440|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.oracle.com/javase/7/docs/api/org/omg/CORBA/package-summary.html^0|0|0|0|0|8|24|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|X|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|Z|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|10|8|@]|9|@$M|11|N|12|1|13]]|A|$]]|$1|O|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]]]

You can import the org.omg.CORBA package(or just the class you need) and in it you can use the Holder classes.

For example, it has the "IntHolder" where the field where it stores the integer is public, giving access to modify it.

<pre><code>public static void triple(IntHolder x){
 x.value = 3 * x.value;
}

IntHolder mutableInt = new IntHolder(10);
triple(mutableInt); 
System.out.println(mutableInt.value);
</code></pre>

It also has "LongHolder" and "DoubleHolder" and tons of others that you can use. Use with caution.

Here is the api for it: <a href="https://docs.oracle.com/javase/7/docs/api/org/omg/CORBA/package-summary.html" rel="nofollow">https://docs.oracle.com/javase/7/docs/api/org/omg/CORBA/package-summary.html</a>

I am in a situation where I want to use mutable versions of things like Integer. Do I have to use these classes (below) or does Java have something built in?

<a href="http://www.java2s.com/Code/Java/Data-Type/Amutableintwrapper.htm" rel="noreferrer">http://www.java2s.com/Code/Java/Data-Type/Amutableintwrapper.htm</a>

Does Java have mutable types for Integer, Float, Double, Long?

Java

我所处的情况是，我想使用像Integer这样的东西的可变版本。我是否必须使用这些类(如下所示)，或者Java是否有内置的类？

问Java有Integer，Float，Double，Long的可变类型吗？
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回答 7

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