java类名与文件名_为什么Java文件名必须与公共类名相同？

java类名与文件名

The question is that "Can we keep different names for java class name and java file name?"

问题是“我们可以为Java类名和Java文件名保留不同的名称吗？”

Yes, we can keep the different name for the java filename and java class name if and only if the class is not public.

是的，当且仅当该类不是公共类时，才能为java文件名和Java类名保留不同的名称。

There are two cases, that we will discuss here...

有两种情况，我们将在这里讨论...

Case 1: We are taking different name if the class is not public
情况1：如果该课程不是公开的，我们将使用其他名称
Case 2: We are taking different name if the class is public
情况2：如果该课程是公开的，我们将使用其他名称

Case 1: We are taking different name if the class is not public

情况1：如果该课程不是公开的，我们将使用其他名称

With the help of an example, we will see what will happen if the class is not public and in that case, we can take a different name for the java class and java file that means it is not mandatory to have the same name for the java class name and java filename in that case.

借助示例，我们将看到如果该类不是公共类，会发生什么情况，在这种情况下，我们可以为java类和java文件取一个不同的名称，这意味着不必强制为该类使用相同的名称。在这种情况下，java类名称和java文件名。

Example:

例：

class ClassIsNotPublic{
public static void main(String[] args){
String str1 = "This class is not public so we can take different name for the java filename and java classname";
String str2 = "This class is not prefixed with public keyword that's why it is not public";
System.out.println("What will happen if we take non public class " +str1);
System.out.println("Why it is not public class "+ str2);
} 
}

Output

输出量

E:\Programs>javac abc.java [abc is java filename]
E:\Programs>java ClassIsNotPublic [ClassIsNotPublic is java classname]
What will happen if we take non public class This class is not public so 
we can take different name for the java filename and java classname
Why it is not public class This class is not prefixed with public keyword 
that's why it is not public

Case 2: We are taking different name if the class is public

情况2：如果该课程是公开的，我们将使用其他名称

If we declared a class as "public" then, in that case, java filename and java class name must be same or in other words, we can’t take any other name for the java class name and java filename in the case of a public class.

如果我们将某个类声明为“ public”，则在这种情况下，java文件名和Java类名必须相同或换句话说，对于Java类名和java文件名，我们不能使用任何其他名称。公共课。

Example:

例：

public class ClassIsPublic{
public static void main(String[] args){
String str1 = "This class is public so we can't take different name for the java filename and java classname";
String str2 = "This class is prefixed with public keyword that's why it is public class";
System.out.println("What will happen if we take public class"+" " +str1);
System.out.println("Why it is public class "+ str2);
} 
}

Output

输出量

E:\Programs>javac xyz.java
xyz.java:1: error: class IfClassIsPublic is public, should be 
declared in a file named IfClassIsPublic.java
public class IfClassIsPublic{
^
1 error

Now we will see why it is required to take the same name for the java filename and java class name in the case of a public class?

现在，我们将看到为什么在公共类的情况下，要求Java文件名和Java类名使用相同的名称？

There are few points to understand why it is required to take the same name?

有几点要理解为什么需要使用相同的名称？

Let suppose we have a java file named "java1000" in that java file we have 1000 classes and in that case if we want to find any single class in 1000 classes so it will be more difficult to find and it will create a lot of confusion.
假设我们有一个名为“ java1000”的java文件，该java文件中有1000个类，在这种情况下，如果我们想在1000个类中找到任何一个类，那么将很难找到它，并且会造成很多混乱。
In that java file we have 1000 classes we know that to find any class in 1000 classes will difficult so, in that case, almost one is class will be public and that public class will contain main() method so all the classes objects will be called from main() method class(i.e. public class) so if we take java filename and public class name will be same then it will be easy to find any class in the public class.
在该java文件中，我们有1000个类，我们知道很难在1000个类中找到任何一个类，因此，在那种情况下，几乎是class是public，而public class将包含main()方法，因此所有class对象都是从main()方法类(即公共类)调用，因此，如果我们使用java文件名，并且公共类名称相同，则可以很容易在公共类中找到任何类。
If our java filename and public class name will be same so by using java filename we can easily reach to public class(main() method class) and if we reach to public class then from that class we can reach to any other class also from the 1000 classes and we know all classes object will be called from the main() method class(i.e. public class).
如果我们的java文件名和公共类名相同，那么通过使用java文件名，我们可以轻松地访问public class(main()方法类)；如果我们访问public类，那么从该类中我们也可以访问任何其他类。 1000个类，我们知道所有类对象都将从main()方法类(即公共类)中调用。