java import“无法找到符号” [英] java import "cannot find symbol"

问题描述

我是关于将Linux工具移植到Windows。该工具在Linux系统上运行良好，但现在在Windows上我得到这个找不到符号的错误。

I'm about porting a linux tool to windows. The tool works fine on linux system, but now on windows I get this "cannot find symbol" error.

我有这个小主要类：

package foo;

import foo.bar;

public class Main {
    public static void main(String[] args) throws Exception {
        bar.getInstance();
    }
}

现在出现错误，同时执行javac Main。 java：

and the error appears now, while doing javac Main.java:

import foo.bar：找不到符号
^
符号：class bar
location：package foo

import foo.bar: cannot find symbol ^ symbol: class bar location: package foo

Main.java和bar.java位于同一目录中。
我缺少什么？

Main.java and bar.java are in the same directory. what am I missing?

推荐答案

首先， bar 应该被称为 Bar 是惯用的...

For one thing, bar should be called Bar to be idiomatic...

理想情况下，你应该从目录上面 Main.java，如下所示：

Ideally, you should compile from the directory above Main.java, like this:

javac -d out foo/Main.java foo/Bar.java

这将创建一个名为out的目录，其中包含另一个目录foo，该目录将包含Main .class和Bar.class。所以从父目录再次运行：

That will create a directory called "out" containing another directory "foo", which will contain Main.class and Bar.class. So from the parent directory again, you could run:

java -cp out foo.Main

源位置 以匹配包结构。您可以从包含 Main.java 和 Bar.java 的目录中调用javac这个：

The source locations don't have to match the package structure. You could just call javac from the directory containing Main.java and Bar.java like this:

javac -cp out Main.java Bar.java

（然后以与以前相同的方式运行它）但是，根据包构建源代码通常更好一点。

(And then run it in the same way as before) However, it's generally a much better idea to structure your source code according to packages.

您可能会发现使用IDE（例如Eclipse或NetBeans）更容易，它将为您处理所有编译等。如果你做想要从命令行构建一个真实的项目，你应该考虑使用一个完整的构建系统，如Ant或Maven。

You may well find it easier to use an IDE (Eclipse or NetBeans, for example) which will handle all the compilation etc for you. If you do want to build a real project from the command line, you should probably look into using a full build system such as Ant or Maven.

（请注意，如果您尝试以相同的方式编译，则在Linux上会遇到与Windows相同的错误。）

(Note that you'd get the same error on Linux as on Windows, if you tried to compile in the same way.)

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