blocks|key|1134551|text|为此，您需要编写某种ObjectConverter。如果您既有要转换的对象，又知道要转换成的目标类，那么这是可行的。在这种情况下，您可以通过Field#getDeclaringClass()获取目标类。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1134552|您可以在here中找到此类ObjectConverter的一个示例。它应该会给你一个基本的概念。如果您想要更多的转换可能性，只需向其添加更多具有所需参数和返回类型的方法即可。|1134553|entityMap|0|LINK|mutability|MUTABLE|url|http://java.sun.com/javase/6/docs/api/java/lang/reflect/Field.html#getDeclaringClass%2528%2529|1|http://balusc.blogspot.com/2007/08/generic-object-converter.html^0|A|F|1Y|P|1Y|P|0|0|D|F|4|4|1|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]|$9|U|A|V|B|C]]|D|@$9|W|A|X|1|Y]]|E|$]]|$1|F|3|G|5|6|7|Z|8|@$9|10|A|11|B|C]]|D|@$9|12|A|13|1|14]]|E|$]]|$1|H|3|-4|5|6|7|15|8|@]|D|@]|E|$]]]|I|$J|$5|K|L|M|E|$N|O]]|P|$5|K|L|M|E|$N|Q]]]]

You'll need to write sort of <code>ObjectConverter</code> for this. This is doable if you have both the object which you want to convert and you know the target class to which you'd like to convert to. In this particular case you can get the target class by <a href="http://java.sun.com/javase/6/docs/api/java/lang/reflect/Field.html#getDeclaringClass%28%29" rel="noreferrer"><code>Field#getDeclaringClass()</code></a>.

You can find <a href="http://balusc.blogspot.com/2007/08/generic-object-converter.html" rel="noreferrer">here</a> an example of such an <code>ObjectConverter</code>. It should give you the base idea. If you want more conversion possibilities, just add more methods to it with the desired argument and return type.

blocks|key|1349967|text|它是有效的，您的方法甚至有一个通用的模式：Adapter+pattern。但当然，(1)它不适用于将java原语转换为对象，以及(2)类必须是自适应的(通常通过实现自定义接口)。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1349968|使用此模式，您可以执行以下操作：|1349969|Wolf+bigBadWolf+=+new+Wolf();
Sheep+sheep+=+(Sheep)+bigBadWolf.getAdapter(Sheep.class);|code-block|syntax|javascript|1349970|和Wolf类中的getAdapter方法：|1349971|public+Object+getAdapter(Class+clazz)+{
++if+(clazz.equals(Sheep.class))+{
++++//+return+a+Sheep+implementation
++++return+getWolfDressedAsSheep(this);
++}

++if+(clazz.equals(String.class))+{
++++//+return+a+String
++++return+this.getName();
++}

++return+null;+//+not+adaptable
}|1349972|对于你的特殊想法--这是不可能的。不能使用字符串值进行强制转换。|1349973|entityMap|0|LINK|mutability|MUTABLE|url|http://en.wikipedia.org/wiki/Adapter_pattern^0|L|F|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@$A|Z|B|10|1|11]]|C|$]]|$1|D|3|E|5|6|7|12|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|13|8|@]|9|@]|C|$I|J]]|$1|K|3|L|5|6|7|14|8|@]|9|@]|C|$]]|$1|M|3|N|5|H|7|15|8|@]|9|@]|C|$I|J]]|$1|O|3|P|5|6|7|16|8|@]|9|@]|C|$]]|$1|Q|3|-4|5|6|7|17|8|@]|9|@]|C|$]]]|R|$S|$5|T|U|V|C|$W|X]]]]

It works and there's even a common pattern for your approach: the <a href="http://en.wikipedia.org/wiki/Adapter_pattern" rel="noreferrer">Adapter pattern</a>. But of course, (1) it does not work for casting java primitives to objects and (2) the class has to be adaptable (usually by implementing a custom interface).

With this pattern you could do something like:

<pre><code>Wolf bigBadWolf = new Wolf();
Sheep sheep = (Sheep) bigBadWolf.getAdapter(Sheep.class);
</code></pre>

and the getAdapter method in Wolf class:

<pre><code>public Object getAdapter(Class clazz) {
 if (clazz.equals(Sheep.class)) {
 // return a Sheep implementation
 return getWolfDressedAsSheep(this);
 }

 if (clazz.equals(String.class)) {
 // return a String
 return this.getName();
 }

 return null; // not adaptable
}
</code></pre>

For you special idea - that is impossible. You can't use a String value for casting.

blocks|key|1134729|text|你的问题不是缺乏“动态转换”。将Integer转换为Double是完全不可能的。您似乎希望为Java提供一种类型的对象，一种可能不兼容类型的字段，并让它以某种方式自动确定如何在类型之间进行转换。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1134730|对于像Java和IMO这样的强类型语言来说，这种事情是非常令人厌恶的，这是有充分理由的。|1134731|你到底想做什么？所有这些反射的使用看起来都很可疑。|1134732|entityMap^0|G|7|Q|6|0|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]|$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Q|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|R|8|@]|D|@]|E|$]]|$1|J|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|K|$]]

Your problem is not the lack of "dynamic casting". Casting <code>Integer</code> to <code>Double</code> isn't possible at all. You seem to want to give Java an object of one type, a field of a possibly incompatible type, and have it somehow automatically figure out how to convert between the types.

This kind of thing is anathema to a strongly typed language like Java, and IMO for very good reasons.

What are you actually trying to do? All that use of reflection looks pretty fishy.

blocks|key|1134795|text|不要这样做。只要有一个适当参数化的构造函数即可。连接参数的设置和类型无论如何都是固定的，因此没有必要完全动态地执行这些操作。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1134796|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Don't do this. Just have a properly parameterized constructor instead. The set and types of the connection parameters are fixed anyway, so there is no point in doing this all dynamically.

blocks|key|1350221|text|可以使用Class.cast()方法完成此操作，该方法将提供的参数动态转换为您拥有的类实例的类型。要获取特定字段的类实例，可以对相关字段使用getType()方法。我在下面给出了一个例子，但请注意，它省略了所有的错误处理，不应该未经修改就使用。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1350222|public+class+Test+{

++++public+String+var1;
++++public+Integer+var2;
}

public+class+Main+{

++++public+static+void+main(String[]+args)+throws+Exception+{
++++++++Map<String,+Object>+map+=+new+HashMap<String,+Object>();
++++++++map.put("var1",+"test");
++++++++map.put("var2",+1);

++++++++Test+t+=+new+Test();

++++++++for+(Map.Entry<String,+Object>+entry+:+map.entrySet())+{
++++++++++++Field+f+=+Test.class.getField(entry.getKey());

++++++++++++f.set(t,+f.getType().cast(entry.getValue()));
++++++++}

++++++++System.out.println(t.var1);
++++++++System.out.println(t.var2);
++++}
}|code-block|syntax|javascript|1350223|entityMap|0|LINK|mutability|MUTABLE|url|http://java.sun.com/javase/6/docs/api/java/lang/Class.html#cast(java.lang.Object)|1|http://java.sun.com/javase/6/docs/api/java/lang/reflect/Field.html#getType()^0|4|C|1Y|9|4|C|0|1Y|9|1|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@$9|Z|A|10|1|11]|$9|12|A|13|1|14]]|E|$]]|$1|F|3|G|5|H|7|15|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|16|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]|S|$5|N|O|P|E|$Q|T]]]]

You can do this using the <a href="http://java.sun.com/javase/6/docs/api/java/lang/Class.html#cast(java.lang.Object)" rel="noreferrer"><code>Class.cast()</code></a> method, which dynamically casts the supplied parameter to the type of the class instance you have. To get the class instance of a particular field, you use the <a href="http://java.sun.com/javase/6/docs/api/java/lang/reflect/Field.html#getType()" rel="noreferrer"><code>getType()</code></a> method on the field in question. I've given an example below, but note that it omits all error handling and shouldn't be used unmodified.

<pre><code>public class Test {

 public String var1;
 public Integer var2;
}

public class Main {

 public static void main(String[] args) throws Exception {
 Map&lt;String, Object&gt; map = new HashMap&lt;String, Object&gt;();
 map.put("var1", "test");
 map.put("var2", 1);

 Test t = new Test();

 for (Map.Entry&lt;String, Object&gt; entry : map.entrySet()) {
 Field f = Test.class.getField(entry.getKey());

 f.set(t, f.getType().cast(entry.getValue()));
 }

 System.out.println(t.var1);
 System.out.println(t.var2);
 }
}
</code></pre>

blocks|key|1135049|text|所以，这是一个古老的帖子，但我认为我可以为它做一些贡献。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1135050|你总是可以这样做的：|1135051|package+com.dyna.test;++

import+java.io.File;++
import+java.lang.reflect.Constructor;++

public+class+DynamicClass{++

++@SuppressWarnings("unchecked")++
++public+Object+castDynamicClass(String+className,+String+value){++
++++Class<?>+dynamicClass;++

++++try++
++++{++
++++++//We+get+the+actual+.class+object+associated+with+the+specified+name++
++++++dynamicClass+=+Class.forName(className);++



++++/*+We+get+the+constructor+that+received+only+
+++++a+String+as+a+parameter,+since+the+value+to+be+used+is+a+String,+but+we+could
easily+change+this+to+be+"dynamic"+as+well,+getting+the+Constructor+signature+from
the+same+datasource+we+get+the+values+from+*/+


++++++Constructor<?>+cons+=++
++++++++(Constructor<?>)+dynamicClass.getConstructor(new+Class<?>[]{String.class});++

++++++/*We+generate+our+object,+without+knowing+until+runtime+
+what+type+it+will+be,+and+we+place+it+in+an+Object+as+
+any+Java+object+extends+the+Object+class)+*/++
++++++Object+object+=+(Object)+cons.newInstance(new+Object[]{value});++

++++++return+object;++
++++}++
++++catch+(Exception+e)++
++++{++
++++++e.printStackTrace();++
++++}++
++++return+null;++
++}++

++public+static+void+main(String[]+args)++
++{+++
++++DynamicClass+dynaClass+=+new+DynamicClass();++

++++/*+
+We+specify+the+type+of+class+that+should+be+used+to+represent+
+the+value+"3.0",+in+this+case+a+Double.+Both+these+parameters+
+you+can+get+from+a+file,+or+a+network+stream+for+example.+*/++
++++System.out.println(dynaClass.castDynamicClass("java.lang.Double",+"3.0"));++

++++/*+
We+specify+a+different+value+and+type,+and+it+will+work+as+
+expected,+printing+3.0+in+the+above+case+and+the+test+path+in+the+one+below,+as+the+Double.toString()+and+
+File.toString()+would+do.+*/++
++++System.out.println(dynaClass.castDynamicClass("java.io.File",+"C:\\testpath"));++
++}++|code-block|syntax|javascript|1135052|当然，这并不像在其他语言(例如Python)中那样是真正的动态类型转换，因为java是一个静态类型的语言。然而，这可以解决一些边缘情况，在这些情况下，您实际上需要以不同的方式加载一些数据，具体取决于某些标识符。此外，通过从相同的数据源传递参数，可以使获取带有字符串参数的构造函数的部分变得更加灵活。例如，从一个文件中，你得到了你想要使用的构造函数签名，以及要使用的值的列表，这样你就配对了，比方说，第一个参数是一个字符串，第一个对象，将它转换为一个字符串，下一个对象是一个整数，等等，但是在你的程序执行过程中，你首先得到一个file对象，然后是一个Double对象，等等。|1135053|通过这种方式，您可以考虑到这些情况，并动态地进行某种程度上的“动态”转换。|1135054|希望这对任何人都有帮助，因为它一直出现在谷歌搜索中。|1135055|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

So, this is an old post, however I think I can contribute something to it.

You can always do something like this:

<pre><code>package com.dyna.test; 

import java.io.File; 
import java.lang.reflect.Constructor; 

public class DynamicClass{ 

 @SuppressWarnings("unchecked") 
 public Object castDynamicClass(String className, String value){ 
 Class&lt;?&gt; dynamicClass; 

 try 
 { 
 //We get the actual .class object associated with the specified name 
 dynamicClass = Class.forName(className); 



 /* We get the constructor that received only 
 a String as a parameter, since the value to be used is a String, but we could
easily change this to be "dynamic" as well, getting the Constructor signature from
the same datasource we get the values from */ 


 Constructor&lt;?&gt; cons = 
 (Constructor&lt;?&gt;) dynamicClass.getConstructor(new Class&lt;?&gt;[]{String.class}); 

 /*We generate our object, without knowing until runtime 
 what type it will be, and we place it in an Object as 
 any Java object extends the Object class) */ 
 Object object = (Object) cons.newInstance(new Object[]{value}); 

 return object; 
 } 
 catch (Exception e) 
 { 
 e.printStackTrace(); 
 } 
 return null; 
 } 

 public static void main(String[] args) 
 { 
 DynamicClass dynaClass = new DynamicClass(); 

 /* 
 We specify the type of class that should be used to represent 
 the value "3.0", in this case a Double. Both these parameters 
 you can get from a file, or a network stream for example. */ 
 System.out.println(dynaClass.castDynamicClass("java.lang.Double", "3.0")); 

 /* 
We specify a different value and type, and it will work as 
 expected, printing 3.0 in the above case and the test path in the one below, as the Double.toString() and 
 File.toString() would do. */ 
 System.out.println(dynaClass.castDynamicClass("java.io.File", "C:\\testpath")); 
 } 
</code></pre>

Of course, this is not really dynamic casting, as in other languages (Python for example), because java is a statically typed lang. However, this can solve some fringe cases where you actually need to load some data in different ways, depending on some identifier. Also, the part where you get a constructor with a String parameter could be probably made more flexible, by having that parameter passed from the same data source. I.e. from a file, you get the constructor signature you want to use, and the list of values to be used, that way you pair up, say, the first parameter is a String, with the first object, casting it as a String, next object is an Integer, etc, but somehwere along the execution of your program, you get now a File object first, then a Double, etc.

In this way, you can account for those cases, and make a somewhat "dynamic" casting on-the-fly.

Hope this helps anyone as this keeps turning up in Google searches.

blocks|key|1135181|text|我最近觉得我也必须这样做，但后来我找到了另一种方法，可能会让我的代码看起来更整洁，并使用更好的OOP。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1135182|我有许多兄弟类，每个类实现一个特定的方法doSomething()。为了访问该方法，我必须首先拥有该类的一个实例，但是我为我的所有兄弟类创建了一个超类，现在我可以从超类访问该方法。|offset|length|style|CODE|1135183|下面我将展示两种“动态类型转换”的替代方法。|1135184|//+Method+1.
mFragment+=+getFragmentManager().findFragmentByTag(MyHelper.getName(mUnitNum));
switch+(mUnitNum)+{
case+0:
++++((MyFragment0)+mFragment).sortNames(sortOptionNum);
++++break;
case+1:
++++((MyFragment1)+mFragment).sortNames(sortOptionNum);
++++break;
case+2:
++++((MyFragment2)+mFragment).sortNames(sortOptionNum);
++++break;
}|code-block|syntax|javascript|1135185|和我目前使用的方法，|1135186|//+Method+2.
mSuperFragment+=+(MySuperFragment)+getFragmentManager().findFragmentByTag(MyHelper.getName(mUnitNum));
mSuperFragment.sortNames(sortOptionNum);|1135187|entityMap^0|0|K|D|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@$D|W|E|X|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|Y|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|Z|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|10|8|@]|9|@]|A|$]]|$1|Q|3|R|5|L|7|11|8|@]|9|@]|A|$M|N]]|$1|S|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|T|$]]

I recently felt like I had to do this too, but then found another way which possibly makes my code look neater, and uses better OOP.

I have many sibling classes that each implement a certain method <code>doSomething()</code>. In order to access that method, I would have to have an instance of that class first, but I created a superclass for all my sibling classes and now I can access the method from the superclass.

Below I show two ways alternative ways to "dynamic casting".

<pre><code>// Method 1.
mFragment = getFragmentManager().findFragmentByTag(MyHelper.getName(mUnitNum));
switch (mUnitNum) {
case 0:
 ((MyFragment0) mFragment).sortNames(sortOptionNum);
 break;
case 1:
 ((MyFragment1) mFragment).sortNames(sortOptionNum);
 break;
case 2:
 ((MyFragment2) mFragment).sortNames(sortOptionNum);
 break;
}
</code></pre>

and my currently used method,

<pre><code>// Method 2.
mSuperFragment = (MySuperFragment) getFragmentManager().findFragmentByTag(MyHelper.getName(mUnitNum));
mSuperFragment.sortNames(sortOptionNum);
</code></pre>

blocks|key|1135272|text|我只是想发布一些我觉得非常有用的东西，对于有类似需求的人来说也是可能的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1135273|下面的方法是我为我的JavaFX应用程序编写的一个方法，它可以避免强制转换，也可以避免在每次返回控制器时编写if+object+x对象b的实例语句。|1135274|public++Optional+getController(Class+castKlazz){
++++try+{
++++++++return+Optional.of(fxmlLoader.getController());
++++}catch+(Exception+e){
++++++++e.printStackTrace();
++++}
++++return+Optional.empty();
}|code-block|syntax|javascript|1135275|用于获取控制器的方法声明是|1135276|public+<T>+T+getController()|1135277|通过使用通过类object传递到我的方法中的类型U，它可以被转发到方法get控制器，以告诉它返回哪种类型的对象。如果提供了错误的类并发生异常，将返回一个可选对象，在这种情况下，将返回一个空的可选对象，我们可以检查该对象。|1135278|对该方法的最终调用如下所示(如果返回的optional对象使用一个Consumer|1135279|getController(LoadController.class).ifPresent(controller->controller.onNotifyComplete());|1135280|entityMap^0|0|0|0|0|0|0|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]]|$1|I|3|J|5|6|7|X|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|Z|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|10|8|@]|9|@]|A|$]]|$1|Q|3|R|5|F|7|11|8|@]|9|@]|A|$G|H]]|$1|S|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|T|$]]

Just thought I would post something that I found quite useful and could be possible for someone who experiences similar needs.

The following method was a method I wrote for my JavaFX application to avoid having to cast and also avoid writing if object x instance of object b statements every time the controller was returned.

<pre><code>public &lt;U&gt; Optional&lt;U&gt; getController(Class&lt;U&gt; castKlazz){
 try {
 return Optional.of(fxmlLoader.&lt;U&gt;getController());
 }catch (Exception e){
 e.printStackTrace();
 }
 return Optional.empty();
}
</code></pre>

The method declaration for obtaining the controller was

<pre><code>public &lt;T&gt; T getController()
</code></pre>

By using type U passed into my method via the class object, it could be forwarded to the method get controller to tell it what type of object to return. An optional object is returned in case the wrong class is supplied and an exception occurs in which case an empty optional will be returned which we can check for.

This is what the final call to the method looked like (if present of the optional object returned takes a Consumer

<pre><code>getController(LoadController.class).ifPresent(controller-&gt;controller.onNotifyComplete());
</code></pre>

blocks|key|1135331|text|你可以像下面这样写一个简单的castMethod。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1135332|private+<T>+T+castObject(Class<T>+clazz,+Object+object)+{
++return+(T)+object;
}|code-block|syntax|javascript|1135333|在你的方法中，你应该像这样使用它|1135334|public+ConnectParams(HashMap<String,Object>+object)+{

for+(Map.Entry<String,+Object>+entry+:+object.entrySet())+{
++++try+{
++++++++Field+f+=++this.getClass().getField(entry.getKey());++++++++++++++++
++++++++f.set(this,+castObject(entry.getValue().getClass(),+entry.getValue());+/*+<=+CASTING+PROBLEM+*/
++++}+catch+(NoSuchFieldException+ex)+{
++++++++log.error("did+not+find+field+'"+%2B+entry.getKey()+%2B+'"');
++++}+catch+(IllegalAccessException+ex)+{++++
++++++++log.error(ex.getMessage());++++++++++
++++}++++
}

}|1135335|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

You can write a simple castMethod like the one below.

<pre><code>private &lt;T&gt; T castObject(Class&lt;T&gt; clazz, Object object) {
 return (T) object;
}
</code></pre>

In your method you should be using it like

<pre><code>public ConnectParams(HashMap&lt;String,Object&gt; object) {

for (Map.Entry&lt;String, Object&gt; entry : object.entrySet()) {
 try {
 Field f = this.getClass().getField(entry.getKey()); 
 f.set(this, castObject(entry.getValue().getClass(), entry.getValue()); /* &lt;= CASTING PROBLEM */
 } catch (NoSuchFieldException ex) {
 log.error("did not find field '" + entry.getKey() + '"');
 } catch (IllegalAccessException ex) { 
 log.error(ex.getMessage()); 
 } 
}

}
</code></pre>

blocks|key|1350690|text|对于动态类型转换，请尝试此方法。它会成功的！|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1350691|++++String+something+=+"1234";
++++String+theType+=+"java.lang.Integer";
++++Class<?>+theClass+=+Class.forName(theType);
++++Constructor<?>+cons+=+theClass.getConstructor(String.class);
++++Object+ob+=++cons.newInstance(something);
++++System.out.println(ob.equals(1234));|code-block|syntax|javascript|1350692|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|$]]

Try this for Dynamic Casting. It will work!!! 

<pre><code> String something = "1234";
 String theType = "java.lang.Integer";
 Class&lt;?&gt; theClass = Class.forName(theType);
 Constructor&lt;?&gt; cons = theClass.getConstructor(String.class);
 Object ob = cons.newInstance(something);
 System.out.println(ob.equals(1234));
</code></pre>

I would like to do dynamic casting for a Java variable, the casting type is stored in a different variable.

This is the regular casting:

<pre><code> String a = (String) 5;
</code></pre>

This is what I want:

<pre><code> String theType = 'String';
 String a = (theType) 5;
</code></pre>

Is this possible, and if so how? Thanks!

<h1>Update</h1>

I'm trying to populate a class with a <code>HashMap</code> that I received.

This is the constructor:

<pre><code>public ConnectParams(HashMap&lt;String,Object&gt; obj) {

 for (Map.Entry&lt;String, Object&gt; entry : obj.entrySet()) {
 try {
 Field f = this.getClass().getField(entry.getKey()); 
 f.set(this, entry.getValue()); /* &lt;= CASTING PROBLEM */
 } catch (NoSuchFieldException ex) {
 log.error("did not find field '" + entry.getKey() + '"');
 } catch (IllegalAccessException ex) {
 log.error(ex.getMessage()); 
 }
 }

}
</code></pre>

The problem here is that some of the class' variables are of type <code>Double</code>, and if the number 3 is received it sees it as <code>Integer</code> and I have type problem.

java: How can I do dynamic casting of a variable from one type to another?

Python

Java

我想对Java变量进行动态强制转换，强制转换类型存储在另一个变量中。这是常规的造型： String a = (String) 5;这就是我想要的： String theType = 'String'; String a = (theType) 5;这是可能的吗?如果是的话，是如何实现的？谢谢!更新我正在尝试用我收到的H...

问java:如何将变量从一种类型动态转换为另一种类型？
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