当我使用 javac 编译几个 .java 文件时，出现了一些 "duplicate class" 错误，但我在代码中找不到错误

Question

当我使用javac编译几个.java文件时，我得到了一些"duplicate class" 错误，但我在我的代码中找不到错误。

有四个 .java 个文件，所有这些文件都在 Windows.

中的同一个文件夹中

MyApp.java 文件中的代码：

import dx.*;
import dx.shapes.*;

class MyApp {
    public static void main(String[] args) {
        System.out.println("This is a test application."); 

        Rectangle rect = new Rectangle(10, 20);
        rect.Speak();

        Circle circle = new Circle(15);
        circle.Speak();

        Worker worker = new Worker();
        worker.Speak();
    }
}

Rectangle.java 文件中的代码：

    package dx.shapes;

    public class Rectangle {
        private int x, y;
        private int width, height;

        public Rectangle() {
            this(0, 0, 1, 1);
        }
        public Rectangle(int width, int height) {
            this(0, 0, width, height);
        }
        public Rectangle(int x, int y, int width, int height) {
            this.x = x;
            this.y = y;
            this.width = width;
            this.height = height;
        }
        public void Speak(){
            System.out.println("I'm a rectangle, width:" + this.width + ", height:" + this.height);
        }
    }

Circle.java文件中的代码：

package dx.shapes;

public class Circle {
    private int x, y;
    private int radius;

    public Circle() {
        this(0, 0, 10);
    }
    public Circle(int radius) {
        this(0, 0, radius);
    }
    public Circle(int x, int y, int radius) {
        this.x = x;
        this.y = y;
        this.radius = radius;
    }
    public void Speak(){
        System.out.println("I'm a circle, radius:" + this.radius);
    }
}

Worker.java 文件中的代码：

package dx;

public class Worker {
    public void Speak(){
        System.out.println("I'm a worker.");
    }
}

在Windows命令行中，我使用javac来编译这些源代码：

javac MyApp.java Rectangle.java Circle.java Worker.java

但我唯一得到的是错误列表：

Rectangle.java:3: error: duplicate class: dx.shapes.Rectangle
public class Rectangle {
       ^
MyApp.java:8: error: cannot access Rectangle
        Rectangle rect = new Rectangle(10, 20);
        ^
  bad source file: .\Rectangle.java
    file does not contain class Rectangle
    Please remove or make sure it appears in the correct subdirectory of the sourcepath.
Circle.java:3: error: duplicate class: dx.shapes.Circle
public class Circle {
       ^
MyApp.java:11: error: cannot access Circle
        Circle circle = new Circle(15);
        ^
  bad source file: .\Circle.java
    file does not contain class Circle
    Please remove or make sure it appears in the correct subdirectory of the sourcepath.
Worker.java:3: error: duplicate class: dx.Worker
public class Worker {
       ^
MyApp.java:14: error: cannot access Worker
        Worker worker = new Worker();
        ^
  bad source file: .\Worker.java
    file does not contain class Worker
    Please remove or make sure it appears in the correct subdirectory of the sourcepath.
6 errors

我不知道怎么了。为什么？

Answer 1

将目录下所有文件全部编译

javac dir_name/*.java

Answer 2

您只能调用主要的 class 即 MyApp 只需编译主要的 class javac MyApp.java 然后 java MyApp

Answer 3

请参考编译器文档：Arrangement of Source Code

主要是：

When classes and interfaces are organized into a package, the package is represented as a directory, and any subpackages are represented as subdirectories.

假设你的源码根目录是src，文件应该排列成

src/
 |
 + - MyApp.java
 |
 + = dx/ 
      |
      + - Worker.java
      |
      + = shapes/
            |
            + - Circle.java
            + - Rectangle.java

要编译更改到 src 目录并使用：

/src> javac *.java dx/*.java dx/shapes/*java

或者，对于 Windows：

C:\src>javac *.java dx\*.java dx\shapes\*java

由于所有类都在 MyApp 中被引用，您可以只编译该文件，编译器将找到并编译另一个类:

src> javac MyApp.java

最好一次编译所有文件，因为（相同的文档）：

The order of source files specified on the command line or in an argument file is not important. javac will compile the files together, as a group, and will automatically resolve any dependencies between the declarations in the various source files.

当我使用 javac 编译几个 .java 文件时，出现了一些 "duplicate class" 错误，但我在代码中找不到错误

When I use javac to complile several .java files, I got some "duplicate class" errors, but I can't find errors in my code

java

javac