If you’ve read my Java 101 tutorial introducing static classes and inner classes, you should be familiar with the basics of working with nested classes in Java code.

Use an editor to enter Listing 2’s source code and save that code to a Usetestpkg1.java file in the root directory. Compile Usetestpkg1.java by typing javac Usetestpkg1.java .

1. The Java compiler: javac. The javac utility is the most important command-line interface tool you will find in the JDK's bin directory. This is the Java compiler, and whether you use Maven, Gradle, ...