一个文件Java中有两个公共类 [英] Two public classes in one file java

问题描述

好吧，这可能是java中的小问题.我们不能在一个文件中定义两个公共类.但是，在《 SCJP学习指南》一书的示例中，提到了以下示例:

Ok, this might be kiddies question in java. We can't define two public classes in one file. But, in one of the examples from the book SCJP study guide, this example was mentioned:

public abstract class A{
    public abstract void show(String data);
}

public class B extends A{
    public void show(String data){
        System.out.println("The string data is "+data);
    }
    public static void main(String [] args){
        B b = new B();
        b.show("Some sample string data");
    }
}

当我将其复制粘贴到netbeans中时，立即引发编译错误，该公共类A应该在单独的文件中提及.SCJP styudy指南中的示例真的错误吗?同样在一些模拟测试中，我发现很多问题都具有这种模式，但是在所有选项中都没有提到编译器错误.在这里担心

When I copy pasted this into netbeans immediately compile error was thrown, that public class A should me mentioned in separate file. Is that example from SCJP styudy guide really wrong? Also in some of the mock test I found many questions having such pattern but in none of the options was a compiler error was mentioned. Getting worried here

推荐答案

是的，一个文件中不允许2个顶级公共类

yes, 2 top level public classes are not allowed in one file

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