java程序无法识别从属类 "package input does not exist"

Question

我试图理解this demonstration example 。仅给出了 HelloWorld 类，因此我必须自己实现 Input 和 Output 类。

我理解错误消息:java 在导入时找不到 Input.java 和 Output.java 文件。因此文件 HelloWorld.class 未正确构建。但我不明白为什么会发生这种情况。我想，我在文件系统或导入的目录结构中犯了一个小错误 - 但我无法发现它。我的错误在哪里？

我还读过2和 3 ，但这也行不通。

<小时/>

HelloWorld.java

package org.fedoraproject.helloworld;

import org.fedoraproject.helloworld.input.Input;
import org.fedoraproject.helloworld.output.Output;

public class HelloWorld {
    public static void main(String[] args) {
        System.out.print("What is your name?: ");
        String reply = Input.getInput();
        Output.output(reply);
    }
}

<小时/>

Input.java

package org.fedoraproject.helloworld;

import java.util.Scanner;

public class Input {

    public static String getInput() {
        Scanner scanner = new Scanner(System.in);
        String returnVal = scanner.next();
        scanner.close();

        return returnVal;
    }

}

<小时/>

输出.java

package org.fedoraproject.helloworld;

public class Output {

    public static void output(String s) {
        System.out.println(s);

    }
}

<小时/>

$ find
.
./src
./src/org
./src/org/fedoraproject
./src/org/fedoraproject/helloworld
./src/org/fedoraproject/helloworld/output
./src/org/fedoraproject/helloworld/output/Output.class
./src/org/fedoraproject/helloworld/output/Output.java
./src/org/fedoraproject/helloworld/input
./src/org/fedoraproject/helloworld/input/Input.class
./src/org/fedoraproject/helloworld/input/Input.java
./src/org/fedoraproject/helloworld/HelloWorld.class
./src/org/fedoraproject/helloworld/HelloWorld.java

<小时/>

$ java -cp src/org/fedoraproject/helloworld/input/Input.class:src/org/fedoraproject/helloworld/output/Output.class src/org/fedoraproject/helloworld/HelloWorld.class
Error: Could not find or load main class src.org.fedoraproject.helloworld.HelloWorld.class

<小时/>

$ javac -cp src/ src/org/fedoraproject/helloworld/HelloWorld.java
src/org/fedoraproject/helloworld/HelloWorld.java:3: error: cannot access Input
import org.fedoraproject.helloworld.input.Input;
                                         ^
  bad source file: src/org/fedoraproject/helloworld/input/Input.java
    file does not contain class org.fedoraproject.helloworld.input.Input
    Please remove or make sure it appears in the correct subdirectory of the sourcepath.

<小时/>

更新:

将 Input.java 和 Output.java 的包声明更改为:

package org.fedoraproject.helloworld.input;
package org.fedoraproject.helloworld.output;

产生(应用答案中的建议):

$ javac -cp src org/fedoraproject/helloworld/HelloWorld.java
org/fedoraproject/helloworld/HelloWorld.java:3: error: package org.fedoraproject.helloworld.input does not exist
import org.fedoraproject.helloworld.input.Input;
                                         ^
org/fedoraproject/helloworld/HelloWorld.java:4: error: package org.fedoraproject.helloworld.output does not exist
import org.fedoraproject.helloworld.output.Output;
                                          ^
org/fedoraproject/helloworld/HelloWorld.java:9: error: cannot find symbol
        String reply = Input.getInput();
                       ^
  symbol:   variable Input
  location: class HelloWorld
org/fedoraproject/helloworld/HelloWorld.java:10: error: cannot find symbol
        Output.output(reply);
        ^
  symbol:   variable Output
  location: class HelloWorld
4 errors

<小时/>

最后更新在这些命令之后，它现在可以工作了，在“src”的父文件夹中执行:

$ find -type f
./src/org/fedoraproject/helloworld/output/Output.java
./src/org/fedoraproject/helloworld/output/Output.class
./src/org/fedoraproject/helloworld/input/Input.class
./src/org/fedoraproject/helloworld/input/Input.java
./src/org/fedoraproject/helloworld/HelloWorld.java
./src/org/fedoraproject/helloworld/HelloWorld.class
~/java-example-project 
$ javac -cp src/ src/org/fedoraproject/helloworld/HelloWorld.java
~/java-example-project 
$ java -cp src org.fedoraproject.helloworld.HelloWorld
What is your name?: toogley
toogley

Answer 1

1.) 更改 Input/Ouput 类的包声明:

package org.fedoraproject.helloworld.input;

package org.fedoraproject.helloworld.output;

因为它们位于input/output文件夹中。

2.) 类路径应设置为所有包的根目录，并且传递的主类应使用完全限定名称:

$ java -cp src org.fedoraproject.helloworld.HelloWorld