Java 如何在 Eclipse 项目中使用外部类文件
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How to Use External Class Files in an Eclipse Project
提问by Kay
My lecturer didn't provide us with the .java files for a tutorial. My question is, how would i use his class files in my eclipse project, and defeat the following error?
我的讲师没有为我们提供教程的 .java 文件。我的问题是，我将如何在我的 eclipse 项目中使用他的类文件，并克服以下错误？
Error:
错误：
Exception in thread "main" java.lang.NoClassDefFoundError: lec/utils/InputReader
at randomIt.main(randomIt.java:17)
Caused by: java.lang.ClassNotFoundException: lec.utils.InputReader
at java.net.URLClassLoader.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 1 more
Here is my code:
这是我的代码：
import java.util.Random;
import lec/utils.InputReader;
public class randomIt {
public static void main(String[] args) {
Random generator = new Random();
InputReader myReader = new InputReader();
//Pick a number randomly between 1 and 10!
int number = generator.nextInt(10)+1;
//Ask user to guess...!
System.out.println("Take a guess (1 to 10)");
if (number == myReader.readInt()){
System.out.println("You win");
}
else {
System.out.println("It was " + number + ", tough Luck");
}
}
And here is my Folder Structure:
Random/
*/ bin
* / lec / utils /InputReader
* / src / randomIt.java
这是我的文件夹结构：
Random/
*/ bin
* / lec / utils /InputReader
* / src / randomIt.java
Note: his class file is "InputReader.class"
注意：他的类文件是“InputReader.class”
回答by Paul Tomblin
In the project configuration menu, there is a "Build Path->Configure Build Path" menu item. Within that, there is an option to add an "external class folder". Put all the provided class files in a folder, and add that folder to the build path.
在项目配置菜单中，有一个“Build Path->Configure Build Path”菜单项。其中，有一个选项可以添加“外部类文件夹”。将所有提供的类文件放在一个文件夹中，并将该文件夹添加到构建路径中。
回答by rajeshnair
You should make the following changes
您应该进行以下更改
Modify your randomIt class to have following include line (no lecs/ ) import utils.InputReader
Modify the filename as rnadmIt.java (and not randomit.java) . The class name and fie name has to be exactly same. Also per Sun convention the class should start with a capital letter
$ cd Random $ javac -classpath ./lec src/randomIt.java
修改您的 randomIt 类以具有以下包含行（无 lecs/ ） import utils.InputReader
将文件名修改为 rnadmIt.java（而不是 randomit.java）。类名和文件名必须完全相同。此外，根据 Sun 约定，该类应以大写字母开头
$ cd 随机 $ javac -classpath ./lec src/randomIt.java
回答by Binary Nerd
I've had a play with Eclipse to work this one out. Give the following a go:
我玩过 Eclipse 来解决这个问题。试一试：
- Create the following directory structure (your desktop will do) classes/lec/utils
- Place the InputReader class file in the utils directory.
- Remove any references you have to InputReader you currently have in your build path.
- Using (right click on project) Properties->Java Build Path->Libraries select the 'Add external class folder' and select the 'classes' folder you created on your desktop and click OK.
- Now in the 'Referenced Libraries' in the project folder you should have one called 'classes' and a package path under that called 'lec.utils' which contains the InputReader class.
- You can use that class using 'import lec.utils.InputReader' in you own class.
- 创建以下目录结构（你的桌面就可以）classes/lec/utils
- 将 InputReader 类文件放在 utils 目录中。
- 删除当前在构建路径中对 InputReader 的所有引用。
- 使用（右键单击项目）Properties->Java Build Path->Libraries 选择“添加外部类文件夹”并选择您在桌面上创建的“类”文件夹，然后单击“确定”。
- 现在，在项目文件夹中的“Referenced Libraries”中，您应该有一个名为“classes”的文件和一个名为“lec.utils”的包路径，其中包含 InputReader 类。
- 您可以在自己的课程中使用“import lec.utils.InputReader”来使用该课程。
Hope that Helps.
希望有帮助。
