例如，如果您在文件夹中，则同时具有.java和.jar文件:

For example, if you are in folder, where you have both your .java and .jar files:

javac -cp "jdbcdriver.jar" checker.java

顺便说一句，类名必须以大写字母开头.

By the way, class names must start with uppercase letter.

UPD: 您应该以相同的方式运行程序

UPD: You should run your program the same way

java -cp "jdbcdriver.jar" checker