blocks|key|2376599|text|你试过了吗|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2376600|Integer.valueOf(5)将5作为整数传递，而不是整数？|offset|length|style|CODE|2376601|entityMap^0|0|0|I|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

Did you try

<code>Integer.valueOf(5)</code> to pass 5 along as an Integer instead of an int?

blocks|key|704807|text|您可以将您的setModelProperty专门用于任何您希望与一起使用的原语：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|704808|protected+void+setModelProperty(String+propertyName,+int+newValue)+{+/*+...+*/+}|code-block|syntax|javascript|704809|或者，您可以在newValue上使用instanceof来检查装箱的原语：|704810|Class[]+classes;
if+(newValue+instanceof+Integer)+{
++classes+=+new+Class[]+{+int.class+};
}+else+if+(newValue+instanceof+Double)+{
++/*+etc...*/
}+else+{
++classes+=+new+Class[]+{newValue.getClass()+};
}|704811|最后，如果您有setFoo的源代码，您可以将其更改为采用装箱的整数而不是整数-开销通常可以忽略不计。|704812|entityMap^0|6|G|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|Y|8|@]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|R|$]]

You could specialise your <code>setModelProperty</code> for any primitives you expect to be used with:

<pre><code>protected void setModelProperty(String propertyName, int newValue) { /* ... */ }
</code></pre>

Alternatively, you could use instanceof on newValue to check for boxed primitives:

<pre><code>Class[] classes;
if (newValue instanceof Integer) {
 classes = new Class[] { int.class };
} else if (newValue instanceof Double) {
 /* etc...*/
} else {
 classes = new Class[] {newValue.getClass() };
}
</code></pre>

Or finally, if you have the source for setFoo, you could change it to take a boxed Integer instead of an int - the overhead is usually negligible.

blocks|key|706645|text|当调用setModelProperty()时，newValue被装箱为整数。这是唯一可以调用它的方法；'int‘不是instanceof对象。newValue.getClass()返回“整数”，因此对getMethod()的调用失败。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|706646|如果你想在这里使用原语，你需要一个特殊版本的setModelProperty。或者，您可以编写一个方法setFoo(整数)。|706647|或者更一般地说，你可以这样写：|706648|if+(newValue.getClass()==Integer.class)+{
++//+code+to+look+for+a+method+with+an+int+argument
}|code-block|syntax|javascript|706649|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|O|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|P|8|@]|9|@]|A|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

newValue is being boxed as an Integer when setModelProperty() is called. This is the only way it can be called; 'int' is not an instanceof Object. newValue.getClass() returns "Integer" and thus the call to getMethod() fails.

If you want to work with primitives here you'll need a special version of setModelProperty. Alternatively you could write a method setFoo(Integer).

Or more generally you could write:

<pre><code>if (newValue.getClass()==Integer.class) {
 // code to look for a method with an int argument
}
</code></pre>

blocks|key|706666|text|type|unstyled|depth|inlineStyleRanges|entityRanges|data|706667|有没有办法说服这个反射代码将5(或者我传入的任何整数)作为一个整数传递，而不进行装箱？|blockquote|706668|706669|706670|当你的方法签名是Object+newValue的时候就不会了，因为int永远不能是Object。保持方法泛型的一种方法是让调用者显式地传入类型，即：|offset|length|style|CODE|706671|protected+void+setModelProperty(String+propertyName,+Object+newValue,+Class+type)+{|code-block|syntax|javascript|706672|或者，您可以测试newValue的类型，以确定它是否是原语包装器，在这种情况下，可以同时查找该方法的原语和包装版本。但是，当用户传入null时，这将不起作用。实际上，在这种情况下，该方法根本不起作用。|706673|entityMap^0|0|0|0|0|8|F|15|6|0|0|8|8|1U|4|0^^$0|@$1|2|3|-4|4|5|6|U|7|@]|8|@]|9|$]]|$1|A|3|B|4|C|6|V|7|@]|8|@]|9|$]]|$1|D|3|-4|4|5|6|W|7|@]|8|@]|9|$]]|$1|E|3|-4|4|5|6|X|7|@]|8|@]|9|$]]|$1|F|3|G|4|5|6|Y|7|@$H|Z|I|10|J|K]|$H|11|I|12|J|K]]|8|@]|9|$]]|$1|L|3|M|4|N|6|13|7|@]|8|@]|9|$O|P]]|$1|Q|3|R|4|5|6|14|7|@$H|15|I|16|J|K]|$H|17|I|18|J|K]]|8|@]|9|$]]|$1|S|3|-4|4|5|6|19|7|@]|8|@]|9|$]]]|T|$]]

<blockquote>
 Is there any way to convince this
 reflection code to pass 5 (or
 whatever int I pass in) as an Integer,
 without the boxing?
</blockquote>

Not while your method signature says <code>Object newValue</code>, because an int can never be an <code>Object</code>. A way to keep the method generic would be to have callers pass in the type explicitly, i.e.:

<pre><code>protected void setModelProperty(String propertyName, Object newValue, Class type) {
</code></pre>

Alternatively, you could test the type of <code>newValue</code> to see if it's a primitive wrapper and in that case look for both the primitive and the wrapped version of the method. However, that won't work when the user passes in a <code>null</code>. Actually, the method won't work at all in that case...

blocks|key|3784639|text|问题不在于调用，而在于获取方法，因为您使用的是与int.class不同的Integer.class。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3784640|如果第一次调用get方法失败，您可以通过第二次调用来修复它：|3784641|protected+void+setModelProperty(String+propertyName,+Object+newValue)+{

++++for+(AbstractModel+model:+registeredModels)+{
++++++++Method+method+=+null;
++++++++try+{
++++++++++++method+=+model.getClass().
+++++++++++++++++getMethod("set"%2BpropertyName,+new+Class[]+{
++++++++++++++++++++++++++++++++++++++++++++++++++newValue.getClass()
+++++++++++++++++++++++++++++++++++++++++++++++}
+++++++++++++++++++++++++);
++++++++}+catch+(Exception+ex)+{
++++++++++++try+{
++++++++++++++++if+(canBoxPrimitive(newValue.getClass())+{
++++++++++++++++++++method+=+model.getClass().
+++++++++++++++++++++++++++getMethod("set"%2BpropertyName,+new+Class[]+{
++++++++++++++++++++++++++++++++++++++++++++++++++primitiveClass(newValue.getClass())
+++++++++++++++++++++++++++++++++++++++++++++++}
++++++++++++++++}
++++++++++++}
++++++++++++catch+(Exception+ex)+{
++++++++++++++++//+handle+it
++++++++++++}
++++++++}

++++++++method.invoke(model,+newValue);
+++}
}|code-block|syntax|javascript|3784642|有关编写函数的选项:布尔类(类)和类primitiveClass(类)，您可以查看此处：Dynamically+find+the+class+that+represents+a+primitive+Java+type|offset|length|3784643|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/180097/dynamically-find-the-class-that-represents-a-primitive-java-type^0|0|0|0|18|1S|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]]]]

Problem is not on invoking but on getting the method, as you are using Integer.class which is different from int.class.

You can fix it by doing a second call to get method if the first one fails:

<pre><code>protected void setModelProperty(String propertyName, Object newValue) {

 for (AbstractModel model: registeredModels) {
 Method method = null;
 try {
 method = model.getClass().
 getMethod("set"+propertyName, new Class[] {
 newValue.getClass()
 }
 );
 } catch (Exception ex) {
 try {
 if (canBoxPrimitive(newValue.getClass()) {
 method = model.getClass().
 getMethod("set"+propertyName, new Class[] {
 primitiveClass(newValue.getClass())
 }
 }
 }
 catch (Exception ex) {
 // handle it
 }
 }

 method.invoke(model, newValue);
 }
}
</code></pre>

For options to code the functions: boolean canBoxPrimitive(Class) and Class primitiveClass(Class) you can take a look here: <a href="https://stackoverflow.com/questions/180097/dynamically-find-the-class-that-represents-a-primitive-java-type">Dynamically find the class that represents a primitive Java type</a>

blocks|key|1450203|text|Outoboxing将完成，但您正在寻找错误的方法。参数类型数组不正确。对于int，类型将是Integer.TYPE而不是Integer.class。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1450204|不管参数类型是什么，都可以尝试下面这样的方法来让它工作(outoboxing可以做到这一点)：|1450205|protected+void+setModelProperty(String+propertyName,+Object+newValue)+{

++++for+(AbstractModel+model:+registeredModels)+{
++++++++try+{
++++++++++++Method+method+=+findSetter(model.getClass(),+propertyName);
++++++++++++method.invoke(model,+newValue);

++++++++}+catch+(Exception+ex)+{
++++++++++++//++Handle+exception.
++++++++++++System.err.println(ex.toString());
++++++++}
++++}
}

private+Method+findSetter(Class<?>+type,+String+propertyName)+{
++++for+(Method+methos+:+type.getMethods())+{
++++++++if+(method.getName().equalsIgnoreCase("set"+%2B+propertyName)+&&+method.getParameterTypes().length+==+1)+{
++++++++++++return+method;
++++++++}
++++}
++++throw+new+NoSuchMethodError("No+setter+for+"+%2B+propertyName);
}|code-block|syntax|javascript|1450206|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Outoboxing will be done, but you are looking for the wrong method. The parameter type array is not correct. For int the type would be Integer.TYPE instead of Integer.class.

Try some like the following to get it working regardless of the parameer type (outoboxing will do it):

<pre><code>protected void setModelProperty(String propertyName, Object newValue) {

 for (AbstractModel model: registeredModels) {
 try {
 Method method = findSetter(model.getClass(), propertyName);
 method.invoke(model, newValue);

 } catch (Exception ex) {
 // Handle exception.
 System.err.println(ex.toString());
 }
 }
}

private Method findSetter(Class&lt;?&gt; type, String propertyName) {
 for (Method methos : type.getMethods()) {
 if (method.getName().equalsIgnoreCase("set" + propertyName) &amp;&amp; method.getParameterTypes().length == 1) {
 return method;
 }
 }
 throw new NoSuchMethodError("No setter for " + propertyName);
}
</code></pre>

I have a method with the signature <code>public void setFoo(int newFoo)</code> in a model I'm writing. I'm using the following code to call it from within my controller:

<pre><code>protected void setModelProperty(String propertyName, Object newValue) {

 for (AbstractModel model: registeredModels) {
 try {
 Method method = model.getClass().
 getMethod("set"+propertyName, new Class[] {
 newValue.getClass()
 }
 );
 method.invoke(model, newValue);

 } catch (Exception ex) {
 // Handle exception.
 System.err.println(ex.toString());
 }
 }
}
</code></pre>

Calling this method like <code>controller.setModelProperty("Foo",5);</code> results in an exception being thrown: <code>java.lang.NoSuchMethodException: foo.bar.models.FooModel.setFoo(java.lang.Integer)</code> -- it looks like the <code>int</code> is being boxed as an <code>Integer</code>, which doesn't match the signature of setFoo. 

Is there any way to convince this reflection code to pass <code>5</code> (or whatever int I pass in) as an Integer, without the boxing? Or do I have to create <code>public void setFoo(Integer newFoo)</code> in my model and unbox explicitly, then call the original setFoo?

Unboxing and Reflection in Java?

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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在我正在编写的模型中，我有一个带有签名public void setFoo(int newFoo)的方法。我使用下面的代码从我的控制器中调用它：protected void setModelProperty(String propertyName, Object newValue) {    for (Abstract...

问Java中的拆箱和反射？
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