blocks|key|2427823|text|换句话说，我想问题是，外部类类型参数能否传递给内部类--泛型类型声明？|type|blockquote|depth|inlineStyleRanges|entityRanges|data|2427824|不是的。外部和内部的静态类之间没有任何关系(比如继承或字段)。您可以创建内部静态类的对象，而不依赖于外部类，如您的示例中所示：|unstyled|offset|length|style|BOLD|2427825|NestedGeneric.InnerGeneric<String>+test2++=+new+NestedGeneric.InnerGeneric<String>();|code-block|syntax|javascript|2427826|但是，当您将(内部类的实例)用作字段时，泛型类型是从外部类派生出来的：|2427827|private+InnerGeneric<T>+innerGenericInstance;

innerGenericInstance+=+new+InnerGeneric<T>();|2427828|第三个变化是将内部类定义为字段(非静态)。|2427829|private+class+InnerGeneric<T>+{
++++public+T+innerGenericField;
}|2427830|它现在将从外部类获得类型，因为它是一个成员变量。|2427831|正如注释中指出的那样，定义内部静态和外部类以及类型只会使读者(以及稍后的时间点)感到困惑。它应该用不同的泛型来声明，如|2427832|public+class+NestedGeneric<T>+{
++++private+InnerGeneric<T>+innerGenericInstance;

++++private+static+class+InnerGeneric+{
++++++++private+U+innerGenericField;
++++}

++++NestedGeneric()+{
++++++++innerGenericInstance+=+new+InnerGeneric<T>();
++++}
}|2427833|entityMap^0|0|A|2|0|0|6|7|0|0|7|D|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|13|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|14|8|@$E|15|F|16|G|H]]|9|@]|A|$]]|$1|I|3|J|5|K|7|17|8|@]|9|@]|A|$L|M]]|$1|N|3|O|5|D|7|18|8|@$E|19|F|1A|G|H]]|9|@]|A|$]]|$1|P|3|Q|5|K|7|1B|8|@]|9|@]|A|$L|M]]|$1|R|3|S|5|D|7|1C|8|@$E|1D|F|1E|G|H]]|9|@]|A|$]]|$1|T|3|U|5|K|7|1F|8|@]|9|@]|A|$L|M]]|$1|V|3|W|5|D|7|1G|8|@]|9|@]|A|$]]|$1|X|3|Y|5|D|7|1H|8|@]|9|@]|A|$]]|$1|Z|3|10|5|K|7|1I|8|@]|9|@]|A|$L|M]]|$1|11|3|-4|5|D|7|1J|8|@]|9|@]|A|$]]]|12|$]]

<blockquote>
 In other words, I suppose the question is, can an outer classes type
 parameters be passed to an inner classes generic type declarations?
</blockquote>

No. There is no relationship (like inheritance or as a field) between the outer and the inner static class. You can create an object of the inner static class without any dependency on the outer class like in your example:

<pre><code>NestedGeneric.InnerGeneric&lt;String&gt; test2 = new NestedGeneric.InnerGeneric&lt;String&gt;();
</code></pre>

However when you use an instance of the inner class as a field the generic type is derived from the outer class:

<pre><code>private InnerGeneric&lt;T&gt; innerGenericInstance;

innerGenericInstance = new InnerGeneric&lt;T&gt;();
</code></pre>

A third variation would be to define the inner class as a field (non-static):

<pre><code>private class InnerGeneric&lt;T&gt; {
 public T innerGenericField;
}
</code></pre>

which will now get the type from the outer class since its a member variable.

As pointed out in the comment defining both inner static &amp; outer class with the type will just confuse the reader (and yourself at a later point in time). It should be declared with a different generic like

<pre><code>public class NestedGeneric&lt;T&gt; {
 private InnerGeneric&lt;T&gt; innerGenericInstance;

 private static class InnerGeneric&lt;U&gt; {
 private U innerGenericField;
 }

 NestedGeneric() {
 innerGenericInstance = new InnerGeneric&lt;T&gt;();
 }
}
</code></pre>

blocks|key|2089881|text|是的，但不使用静态修饰符：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2089882|public+class+NestedGeneric<T>+{
++++private+InnerGeneric<T>+innerGenericInstance;

++++private+class+InnerGeneric<T>+{
++++++++private+T+innerGenericField;

++++++++public+InnerGeneric(T+innerGenericField){
+++++++++++this.innerGenericField+=+innerGenericField;
++++++++}

++++++++public+T+getInnerGenericField(){
+++++++++++return+this.innerGenericField;
++++++++}
++++}

++++NestedGeneric(T+someGenericVariable)+{
++++++++innerGenericInstance+=+new+InnerGeneric<T>(someGenericVariable);
++++++++T+innerGenericField+=+innerGenericInstance.innerGenericInstance();
++++}
}|code-block|syntax|javascript|2089883|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|$]]

Yes, but not with the static modifier:

<pre><code>public class NestedGeneric&lt;T&gt; {
 private InnerGeneric&lt;T&gt; innerGenericInstance;

 private class InnerGeneric&lt;T&gt; {
 private T innerGenericField;

 public InnerGeneric(T innerGenericField){
 this.innerGenericField = innerGenericField;
 }

 public T getInnerGenericField(){
 return this.innerGenericField;
 }
 }

 NestedGeneric(T someGenericVariable) {
 innerGenericInstance = new InnerGeneric&lt;T&gt;(someGenericVariable);
 T innerGenericField = innerGenericInstance.innerGenericInstance();
 }
}
</code></pre>

blocks|key|2089906|text|这不是阴影。代码中只有一个类型参数，即T参数。因此，内部和外部T是相同的类型参数。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2089907|当然，您可以拥有更多的类型参数。|2089908|public+class+NestedGeneric<OUTER_TYPE>+{

++private+static+class+InnerGeneric<INNER_TYPE>+{
++++public+INNER_TYPE+innerGenericField;
++}

++public+NestedGeneric()+{
++++InnerGeneric<OUTER_TYPE>+innerGenericInstance+=+new+InnerGeneric<OUTER_TYPE>();

+++InnerGeneric<String>+secondInnerGenerics+=+new+InnerGeneric<String>();
++}+
}|code-block|syntax|javascript|2089909|INNER_TYPE和OUTER_TYPE是两个不同的类型参数。行InnerGeneric<OUTER_TYPE>++innerGenericInstance+=+new+InnerGeneric<OUTER_TYPE>();会说thad+innerGenericInstance是由与OUTER_TYPE相同类型的参数化的。但它们不一定是一样的。与secondInnerGenerics变量的情况一样。|2089910|entityMap^0|J|1|V|1|0|0|0|0|A|B|A|X|28|3C|K|3Z|A|4V|J|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|V|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|W|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|X|8|@$9|Y|A|Z|B|C]|$9|10|A|11|B|C]|$9|12|A|13|B|C]|$9|14|A|15|B|C]|$9|16|A|17|B|C]|$9|18|A|19|B|C]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|1A|8|@]|D|@]|E|$]]]|P|$]]

This is not a shadowing. There is only one type parameter int your code, the <code>T</code> parameter. So inner and outer <code>T</code> are the same type parameters. 

You can of course have more type parameters.

<pre><code>public class NestedGeneric&lt;OUTER_TYPE&gt; {

 private static class InnerGeneric&lt;INNER_TYPE&gt; {
 public INNER_TYPE innerGenericField;
 }

 public NestedGeneric() {
 InnerGeneric&lt;OUTER_TYPE&gt; innerGenericInstance = new InnerGeneric&lt;OUTER_TYPE&gt;();

 InnerGeneric&lt;String&gt; secondInnerGenerics = new InnerGeneric&lt;String&gt;();
 } 
}
</code></pre>

The <code>INNER_TYPE</code> and the <code>OUTER_TYPE</code> are two different type parameters. Line <code>InnerGeneric&lt;OUTER_TYPE&gt; innerGenericInstance = new InnerGeneric&lt;OUTER_TYPE&gt;();</code> will say thad <code>innerGenericInstance</code> is parametrized by the same type as <code>OUTER_TYPE</code> is. But they do not have to be the same. As it is in the case of <code>secondInnerGenerics</code> variable.

Does Java shadow type parameters? I am finding it hard to test for myself because Java generics do not get reified at run time.

For example, given this code:

<pre><code>public class NestedGeneric&lt;T&gt; {
 private InnerGeneric&lt;T&gt; innerGenericInstance;

 private static class InnerGeneric&lt;T&gt; {
 public T innerGenericField;
 }

 NestedGeneric() {
 innerGenericInstance = new InnerGeneric&lt;T&gt;();
 }
}
</code></pre>

Both the below statements compile fine:

<pre><code>NestedGeneric&lt;Integer&gt; test1 = new NestedGeneric&lt;Integer&gt;();
NestedGeneric.InnerGeneric&lt;String&gt; test2 = new NestedGeneric.InnerGeneric&lt;String&gt;();
</code></pre>

When the <code>NestedGeneric</code> is passed a type parameter and its constructor called, what is <code>T</code>? Is it always going to be the same as the type parameter passed to <code>nestedGeneric</code>?

In other words, can an outer classes type parameters be passed to an inner classes generic type declarations?

Type declaration based on type parameters in inner classes

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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Java阴影类型参数吗？我发现自己很难进行测试，因为Java泛型在运行时没有被具体化。例如，给定以下代码：public class NestedGeneric<T> { private InnerGeneric<T> innerGenericInstance; private static class In...

问基于内部类中类型参数的类型声明
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