blocks|key|4029939|text|创建属性/变量的要点是，您希望它们作为对象的一个“特性”。例如，如果你有一个类"+car+"，也许你想要一个变量来引用汽车的颜色。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4029940|问题是，"Car“的每个实例(在现实世界中是每个不同的汽车)都有一个值，因此每个实例都必须是一个”独立“变量。|4029941|对于那些由该类的所有对象共享的变量，可以使用静态变量。例如，一个计数器来确定有多少辆车。这个变量属于名为"Car“的类，但不属于该类的任何特定实例。|4029942|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|$]]

The point on creating attributes/variables is that you'll want them as a "feature" for the object. For example, if you have a class "Car", maybe you'll want a variable to reference the color of the car.

The problem is that every instance of "Car" (in real world it'll be each different car) has a value, so each has to be an "independent" variable.

You can use static variables for those ones that are shared by all the objects of this class. For example, a counter to determine how many cars are there. This variable belongs to the class called "Car", but not to any specific instance of that class.

blocks|key|1458565|text|这是面向对象编程的基础知识。看一个例子：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1458566|class+Person+{
++++public+String+name+=+"Foo";
}|code-block|syntax|javascript|1458567|字段name不是静态的，这意味着类Person的对象不会共享它，每个人都有自己的名字。当你改变一个人的名字时，其他人不会受到影响。但是如果你把它设为静态的：|offset|length|style|CODE|1458568|class+Person+{
++++public+static+String+name+=+"Foo";
}|1458569|这意味着，所有的人都有相同的名字，这有点奇怪，你同意吗？)|1458570|entityMap^0|0|0|2|4|H|6|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@$I|V|J|W|K|L]|$I|X|J|Y|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|10|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|R|$]]

It's the basics of OOP. Look at an example:

<pre><code>class Person {
 public String name = "Foo";
}
</code></pre>

Field <code>name</code> is not static, it means that objects of class <code>Person</code> will not share it and each person will have it's own name. And when you change one's person name others will stay unaffected. But if you make it static:

<pre><code>class Person {
 public static String name = "Foo";
}
</code></pre>

It means, that all persons share the same name which is kind of strange, do you agree?)

blocks|key|1453815|text|静态变量是按类级别创建的。它不是在创建类的对象时创建的。对于类的每个实例或对象，静态成员变量只有一个值。这违背了拥有对象和围绕对象创建应用程序的目的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1453816|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|$]]

Static variable are created per class level. It is not created when an Object of the class is created. For every instance or object of the class there is only one value of a static member variable. This defeats the purpose of having objects and creating an application around objects.

blocks|key|5498633|text|是的，它将在生命周期中被分配一次内存，并被称为类变量。可以通过类直接访问类变量，而不需要创建实例。这将意味着它可以从任何地方和任何地方访问。此外，内存分配意味着，即使在代码中的许多地方没有使用变量，只要程序运行，它就会永远留在内存中，并会占用不必要的空间。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5498634|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|$]]

Yes, it would be allocated memory once in the life cycle and is known as class variable. A class variable can be accessed directly with the class, without the need to create an instance. This would mean that it can be accessed from anywhere and everywhere. Also, memory allocation would mean that even if the variable is not used at many places in the code it would stay in the memory forever as long as the program is running and would take up unnecessary space.

I am new to Java and recently I have studied about static variables. I got to know that for a static variable memory is allocated only once. This means that it will save a lot of memory.My question is that if static variables saves memory, why not declare every variable as static. This will save a lot of memory while creating an application. Pardon me if this seems a silly question, but actually I am just a bit curious.

why not declare every variables as Static

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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我对Java是个新手，最近我学习了静态变量。我知道对于一个静态变量，内存只分配一次。这意味着它将节省大量的memory.My问题是，如果静态变量节省内存，为什么不将每个变量都声明为静态变量。这将在创建应用程序时节省大量内存。如果这看起来是一个愚蠢的问题，请原谅，但实际上我只是有点好奇。

问为什么不把每个变量都声明为静态
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