Checkstyle is a Java program contained in the Checkstyle JAR file. To run it on a single java file, use the following command format:
java -jar <PATH TO CHECKSTYLE JAR> -c <PATH TO CHECKSTYLE CONFIGURATION XML> <PATH TO JAVA FILE>
For example, if using the checkstyle-9.1-all.jar version of Checkstyle on the Google configuration file google_checks.xml on the Java file HashTable.java all stored in current working directory, you would run:
java -jar checkstyle-9.1-all.jar -c google_checks.xml HashTable.java