blocks|key|1158540|text|默认情况下，顶级类是静态的。内部类默认情况下是非静态的。您可以通过显式地将内部类标记为静态来更改内部类的默认值。顶层类由于是顶层类，不能具有非静态语义，因为不能有父类可供引用。因此，无法更改顶级类的默认值。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1158541|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|$]]

Top level classes are static by default. Inner classes are non-static by default. You can change the default for inner classes by explicitly marking them static. Top level classes, by virtue of being top-level, cannot have non-static semantics because there can be no parent class to refer to. Therefore, there is no way to change the default for top-level classes.

blocks|key|944276|text|所以，我来晚了，但这里是我的两点-哲学上补充科林·赫伯特的答案。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|944277|在较高的层次上，您的问题涉及对象和类型之间的差异。虽然有许多汽车(对象)，但只有一个汽车类别(类型)。将某些东西声明为静态意味着您是在“类型”空间中操作。只有一个。顶级class关键字已经在"+type“空间中定义了一个类型。因此，"public+static+class+Car“是多余的。|944278|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

So, I'm coming late to the party, but here's my two cents - philosophically adding to Colin Hebert's answer.

At a high level your question deals with the difference between objects and types. While there are many cars (objects), there is only one Car class (type). Declaring something as static means that you are operating in the "type" space. There is only one. The top-level class keyword already defines a type in the "type" space. As a result "public static class Car" is redundant.

blocks|key|1158132|text|具有私有构造函数的类是静态的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1158133|像这样声明你的类：|1158134|public+class+eOAuth+{

++++private+eOAuth(){}

++++public+final+static+int++++ECodeOauthInvalidGrant+=+0x1;
++++public+final+static+int++++ECodeOauthUnknown+++++++=+0x10;
++++public+static+GetSomeStuff(){}

}|code-block|syntax|javascript|1158135|你可以不需要初始化就可以使用：|1158136|if+(value+==+eOAuth.ECodeOauthInvalidGrant)
++++eOAuth.GetSomeStuff();
...|1158137|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Class with private constructor is static.

Declare your class like this:

<pre><code>public class eOAuth {

 private eOAuth(){}

 public final static int ECodeOauthInvalidGrant = 0x1;
 public final static int ECodeOauthUnknown = 0x10;
 public static GetSomeStuff(){}

}
</code></pre>

and you can used without initialization:

<pre><code>if (value == eOAuth.ECodeOauthInvalidGrant)
 eOAuth.GetSomeStuff();
...
</code></pre>

blocks|key|1158076|text|您可以通过声明不带实例的枚举类型来创建实用程序类(不能创建实例)。也就是说，您明确声明没有实例。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1158077|public+enum+MyUtilities+{;
+++public+static+void+myMethod();
}|code-block|syntax|javascript|1158078|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 can create a utility class (which cannot have instances created) by declaring an enum type with no instances. i.e. you are specificly declaring that there are no instances.

<pre><code>public enum MyUtilities {;
 public static void myMethod();
}
</code></pre>

blocks|key|944232|text|除了Java如何定义静态内部类之外，根据C#世界+[1]，还有另一种静态类的定义。静态类是只有静态方法(函数)的类，它的目的是支持过程化编程。这样的类并不是真正的类，因为类的用户只对helper函数感兴趣，而不是创建类的实例。虽然在C#中支持静态类，但是在Java语言中不存在这样的直接支持。但是，您可以使用枚举来模拟Java语言中的C#静态类，这样用户就永远不能创建给定类的实例(即使使用反射)++[2]|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|944233|public+enum+StaticClass2+{
++++//+Empty+enum+trick+to+avoid+instance+creation
++++;+//+this+semi-colon+is+important

++++public+static+boolean+isEmpty(final+String+s)+{
++++++++return+s+==+null+%7C%7C+s.isEmpty();
++++}
}|code-block|syntax|javascript|944234|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/79b3xss3%2528v=vs.80%2529.aspx|1|http://shamsmi.blogspot.com/2013/05/emptytons-mimicking-static-classes-in.html^0|O|4|0|5J|4|1|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]|$A|W|B|X|1|Y]]|C|$]]|$1|D|3|E|5|F|7|Z|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|10|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]|Q|$5|L|M|N|C|$O|R]]]]

In addition to how Java defines static inner classes, there is another definition of static classes as per the C# world<a href="http://msdn.microsoft.com/en-us/library/79b3xss3%28v=vs.80%29.aspx" rel="nofollow"> [1]</a>. A static class is one that has only static methods (functions) and it is meant to support procedural programming. Such classes aren't really classes in that the user of the class is only interested in the helper functions and not in creating instances of the class. While static classes are supported in C#, no such direct support exists in Java. You can however use enums to mimic C# static classes in Java so that a user can never create instances of a given class (even using reflection) <a href="http://shamsmi.blogspot.com/2013/05/emptytons-mimicking-static-classes-in.html" rel="nofollow"> [2]</a>:

<pre><code>public enum StaticClass2 {
 // Empty enum trick to avoid instance creation
 ; // this semi-colon is important

 public static boolean isEmpty(final String s) {
 return s == null || s.isEmpty();
 }
}
</code></pre>

blocks|key|944419|text|我们在java中编写的所有代码都放在一个类中。每当我们运行一个类时，JVM都会实例化一个对象。JVM可以创建许多对象，根据定义，静态意味着您对所有对象都有相同的一组副本。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|944420|因此，如果Java允许顶级类在您运行程序时是静态的，那么它将创建一个对象并一直覆盖到相同的内存位置。|944421|如果您只是在每次运行对象时替换它，那么创建它的意义是什么？|944422|这就是为什么Java摆脱了顶级类的静态。|944423|可能还有更具体的原因，但这对我来说很有逻辑。|944424|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|M|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|N|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|O|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|P|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|K|$]]

Everything we code in java goes into a class. Whenever we run a class JVM instantiates an object. JVM can create a number of objects, by definition Static means you have the same set of copy to all objects.

So, if Java would have allowed the top class to be static whenever you run a program it creates an Object and keeps overriding on to the same Memory Location. 

If You are just replacing the object every time you run it whats the point of creating it?

So that is the reason Java got rid of the static for top-Level Class.

There might be more concrete reasons but this made much logical sense to me.

blocks|key|944326|text|唯一可以是静态的类是内部类。下面的代码运行得很好：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|944327|public+class+whatever+{
++++static+class+innerclass+{
++++}
}|code-block|syntax|javascript|944328|静态内部类的要点是它们没有对外部类对象的引用。|944329|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|$]]

The only classes that can be static are inner classes. The following code works just fine:

<pre><code>public class whatever {
 static class innerclass {
 }
}
</code></pre>

The point of static inner classes is that they don't have a reference to the outer class object.

blocks|key|944002|text|我想这就像喝一杯咖啡一样容易！看看这个。我们在定义类时没有显式地使用static关键字。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|944003|public+class+StaticClass+{

++++static+private+int+me+=+3;
++++public+static+void+printHelloWorld()+{
+++++++System.out.println("Hello+World");
++++}



++++public+static+void+main(String[]+args)+{
++++++++StaticClass.printHelloWorld();
++++++++System.out.println(StaticClass.me);
++++}
}|code-block|syntax|javascript|944004|这不是静态类的定义吗？我们只使用一个绑定到一个类的函数。注意，在这种情况下，我们可以在嵌套中使用另一个类。看看这个：|944005|class+StaticClass1+{

++++public+static+int+yum+=+4;

++++static+void++printHowAreYou()+{
++++++++System.out.println("How+are+you?");
++++}
}

public+class+StaticClass+{

++++static+int+me+=+3;+
++++public+static+void+printHelloWorld()+{
+++++++System.out.println("Hello+World");
+++++++StaticClass1.printHowAreYou();
+++++++System.out.println(StaticClass1.yum);
++++}



++++public+static+void+main(String[]+args)+{
++++++++StaticClass.printHelloWorld();
++++++++System.out.println(StaticClass.me);
++++}
}|944006|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|$]]

I think this is possible as easy as drink a glass of coffee!.
Just take a look at this.
We do not use static keyword explicitly while defining class.

<pre><code>public class StaticClass {

 static private int me = 3;
 public static void printHelloWorld() {
 System.out.println("Hello World");
 }



 public static void main(String[] args) {
 StaticClass.printHelloWorld();
 System.out.println(StaticClass.me);
 }
}
</code></pre>

Is not that a definition of static class?
We just use a function binded to just a class.
Be careful that in this case we can use another class in that nested.
Look at this:

<pre><code>class StaticClass1 {

 public static int yum = 4;

 static void printHowAreYou() {
 System.out.println("How are you?");
 }
}

public class StaticClass {

 static int me = 3; 
 public static void printHelloWorld() {
 System.out.println("Hello World");
 StaticClass1.printHowAreYou();
 System.out.println(StaticClass1.yum);
 }



 public static void main(String[] args) {
 StaticClass.printHelloWorld();
 System.out.println(StaticClass.me);
 }
}
</code></pre>

blocks|key|944107|text|你可以看看Eclipse中的PlatformUI，它是一个具有静态方法和私有构造函数的类，其本身是最终的。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|944108|public+final+class+<class+name>
{
+++//static+constants
+++//static+memebers
}|code-block|syntax|javascript|944109|entityMap^0|E|A|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

One can look at <code>PlatformUI</code> in Eclipse for a class with static methods and private constructor with itself being final.

<pre><code>public final class &lt;class name&gt;
{
 //static constants
 //static memebers
}
</code></pre>

blocks|key|944164|text|如果使用静态类的好处不是实例化对象和使用方法，那么只需将类声明为public，并将此方法声明为static。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|944165|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|$]]

if the benefit of using a static-class was not to instantiate an object and using a method then just declare the class as public and this method as static.

Why are you not able to declare a class as static in Java?

Why are you not able to declare a class as static in Java?

为什么不能在Java中将类声明为static？

问为什么不能在Java中将类声明为static？
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