Printf for Java is a pure Java implementation of the famous printf data formatting function. It supports precompiled format strings for faster processing and an object-oriented data model for maximum flexibility. Printf for Java has helped hundreds of programmers port legacy C applications to Java.
JShell is a UNIX-like shell written in Java, and intended primarily for working with Java programs. It was written to simplify Java development on Psion's 5mx, but can be used with any JDK 1.1.x (or higher) JVM on Windows, Linux, or other Unixes. JShell's features include directory commands (ls, cd, pushd, popd, dirs, etc.), examining and setting environment variables, Java compilation and execution (compilation is done using javac), piping and redirection, support for background jobs (running and killing jobs in the background), and command recall (history, !!, !).
JStart gives the ability to start Java class files (or applets) by double clicking on them from the desktop like any executable program. You only have to assign *.class files to this program. It loads a class file, investigates it according to the Java Sun class file specification, extracts the full class name (including packages), and invokes the main method of that class.