Classpath is empty. Please build the project first e.g. by running 'gradlew jarAll'

这是一个错误提示，意思是类路径为空，请先构建项目，例如通过运行“gradlew jarAll”来构建。这个错误通常发生在使用Java编译器编译项目时，因为编译器无法找到所需的类文件。解决这个问题的方法是确保项目已经构建，并且所有必需的类文件都在类路径上。您可以尝试运行上述命令来构建项目并解决这个问题。

相关问题

Classpath is empty. Please build the project first e.g. by running './gradlew jar -PscalaVersion=2.13.10'

这个错误是因为项目的classpath为空，需要先构建项目。下面是解决方法：

1. 进入项目的根目录

2. 运行以下命令构建项目：

./gradlew jar -PscalaVersion=2.13.10

这个命令会编译项目并生成jar包，同时设置Scala的版本为2.13.10。

3. 构建完成后，重新运行程序即可。

如果还有其他的错误，请根据错误信息进行调整。

Gradle version 2.2 is required. Current version is 3.0. Please fix the project's Gradle settings. Gradle Settings.

This error message means that the Gradle version being used by the project is not compatible with the required version. To fix this issue, you can either update the Gradle version of your project to version 2.2 or downgrade the current Gradle version to version 2.2.

To update the Gradle version of your project, you can follow these steps:

1. Open the build.gradle file of your project.
2. Find the line that specifies the Gradle version, it should look like this: `classpath 'com.android.tools.build:gradle:3.0.0'`
3. Replace the Gradle version number with the required version number, which is 2.2: `classpath 'com.android.tools.build:gradle:2.2.0'`
4. Sync your project with the Gradle files to apply the changes.

If you want to downgrade the current Gradle version to version 2.2, you can follow these steps:

1. Open the Gradle distribution website at https://services.gradle.org/distributions/
2. Download the Gradle version 2.2 distribution by clicking on the link that says `gradle-2.2-all.zip`
3. Extract the downloaded file into a new folder on your computer.
4. Open the `gradle/wrapper/gradle-wrapper.properties` file of your project.
5. Change the following line: `distributionUrl=https\://services.gradle.org/distributions/gradle-3.0-all.zip`
6. To: `distributionUrl=file:///path/to/gradle-2.2-all.zip`
7. Replace `/path/to/gradle-2.2-all.zip` with the actual path to the extracted Gradle 2.2 distribution on your computer.
8. Sync your project with the Gradle files to apply the changes.

After following either of these steps, the project should now be using the required Gradle version and the error message should no longer appear.