请提供以下错误的含义

public class Test9 //在这里收到错误

{

public static void run（）

{

System.out.println（运行中）;

}



public static void fly（）

{

System.out.println（飞行中）;

}

}



公共类GoodDeveloper {



public static void main（String [] args）{

Test9.run（ ）;

Test9.fly（）;



}



}



我尝试了什么：



在上面的注释行我我得到的错误如公共类型Test9必须在其自己的文件中定义。请建议此错误的含义（但我知道解决方案。即删除公众）



请告诉我为什么我不能将我的课程设为公共

public class Test9 // getting error here
{
public static void run()
{
System.out.println("In run");
}

public static void fly()
{
System.out.println("In fly");
}
}

public class GoodDeveloper {

public static void main(String[] args) {
Test9.run();
Test9.fly();

}

}

What I have tried:

in the above commented line I am getting error like "the public type Test9 must be defined in its own file. Please suggest the meaning of this error( however i know the solution. i.e. removing public)

Please tell me why I cannot make my class as public