在java中导入类文件 [英] import class file in java

问题描述

我有一个主目录（包含main.java）和一个子目录（包含child.java）。

I have a main directory (contains main.java) and a subdirectory( contains child.java).

我的问题是如何在main.java中实例化child.java

My problem is how to instantiate child.java in main.java

1. 我让孩子上课了。 &安培;将第1行添加为包mypackage


2. 我编译了 child.class 使用 javac -d。 child.java 创建一个新的mypackage目录。


3. 我试图在main中导入子类，如下所示： import subdirectory.mypackage。 * （注意-d选项将child.class放在mypackage文件夹中）


4. 我使用javac main.java编译了main.java文件

1. I have made the child class public. & added the line#1 as package mypackage
2. I have compiled child.class with javac -d . child.java which creates a new mypackage directory.
3. I tried to import child class in main as follows: import subdirectory.mypackage.* (note -d option places the child.class inside mypackage folder)
4. I compiled the main.java file with "javac main.java"

我收到以下错误：

mainAESE.java:9: cannot access subdirectory.child
bad class file: RegularFileObject[./subdirectory/child
class file contains wrong class: mypackage.child
Please remove or make sure it appears in the correct subdirectory of the class
child childInstance= new child();
^
1 error

请帮助我!!

推荐答案

确保包文件夹 mypackage 和 Main.class 分享父文件夹。

Be ensure that the package folder mypackage and Main.class share the parent folder.

package mypackage;
public class Child {}

我认为 Main 类在默认包中创建。

I presume that the Main class is created in default package.

public class Main {
   public static void main(String []args){
         mypackage.Child child=new mypackage.Child();
   }
}

您的目录结构应为：

main-directory/
              |
              |----/mypackage/
                            Child.class
              |
              | Main.class
              | Main.java
              | Child.java

并启动/加载 Main 发出以下命令，

and to launch/load the Main issue following command,

java Main

java Main

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