The Java Tutorials have been written for JDK 8.Java教程是为JDK 8编写的。Examples and practices described in this page don't take advantage of improvements introduced in later releases and might use technology no longer available.本页中描述的示例和实践没有利用后续版本中引入的改进，并且可能使用不再可用的技术。See Java Language Changes for a summary of updated language features in Java SE 9 and subsequent releases.有关Java SE 9及其后续版本中更新的语言特性的摘要，请参阅Java语言更改。
See JDK Release Notes for information about new features, enhancements, and removed or deprecated options for all JDK releases.有关所有JDK版本的新功能、增强功能以及已删除或不推荐的选项的信息，请参阅JDK发行说明。
The first thing you need is a contract file. You can download and use this very basic sample file named contract. Or you can use any other file you like. Just be sure to name the file contract so it will work with the commands specified in this lesson.
Once you've got the contract file, place it into a JAR file. In your command window type the following:
jar cvf Contract.jar contract
This command creates a JAR file named Contract.jar and places the contract file inside it.