Java Tools Terminology

This section provides quick descriptions of terms related to Java tools.

Certificate: A digitally signed statement from the issuer saying that the public key of the subject has some specific value.

Certificate Chain: A series of certificates that one certificate signs the public key of the issuer of the next certificate. Usually the top certificate (the first certificate) is self-signed, where issuer signed its own public key.

JAR (Java Archive): A platform-independent file format that aggregates many files into one. Multiple Java applets and their requisite components (.class files, images and sounds) can be bundled in a JAR file and subsequently downloaded to a browser in a single HTTP transaction, greatly improving the download speed. The JAR format also supports compression, which reduces the file size, further improving the download time. In addition, the applet author can digitally sign individual entries in a JAR file to authenticate their origin. It is fully extensible.

"jar": A command line tool for managing JAR files. "jar" is distributed as part of the JDK package from Sun.

"java": The Java launcher - A command line tool to launch Java applications. "java" is distributed as part of the JDK package from Sun.

"javac": The Java compiler - A command line tool to compile Java source files. "javac" is distributed as part of the JDK package from Sun.

"javap": The Java Class File Disassembler - A command line tool that reads Java bytecode class files and disassembles them.

"jconsole": A graphical user interface tool that enables you to monitor and manage Java applications and virtual machines on a local or remote machine using the JMX technology.

"jdb": The Java Debugger - A command line tool to debug Java applications. "jdb" is distributed as part of the JDK package from Sun.

"JDI (Java Debug Interface)": A high level Java API providing information useful for debuggers and similar systems needing access to the running state of a (usually remote) virtual machine.

"jhat" - Heap Dump Browser: Starts a Web server on a Java heap dump file (eg, produced by "jmap -dump"), allowing the heap to be browsed.

"jinfo": Prints configuration information for a given JVM process or a Java core file on the local machine or on a remote machine through a debug server.

"jmap" - Memory Map: Prints shared object memory maps or heap memory details of a given JVM process or a Java core file on the local machine or on a remote machine through a debug server.

"JMX (Java Management Extensions)": A Java standard API for management and monitoring of resources such as applications, devices, services, and the Java virtual machine. The JMX technology was developed through the Java Community Process (JCP) as Java Specification Request (JSR) 3, Java Management Extensions, and JSR 160, JMX Remote API.

"JPDA (Java Platform Debugger Architecture)": An infrastructure that allows user to build end-user debugger applications. It includes the following three-layered APIs:

"jps": A new Java tool that lists all JVM processes on the local machine or a remote machine. "jps" tool is distributed as part of the JDK package and represented by the \Progra~1\java\jdk*\bin\jps.exe program file. "jps" can be executed with the following syntax:

"jsadebugd" - Serviceability Agent Debug Daemon: Attaches to a JVM process or a Java core file and acts as a debug server for remote tools to connect.

"jstack" - Stack Trace: Prints a stack trace of threads for a given JVM process or a Java core file on the local machine or on a remote machine through a debug server.

"jstat": A JVM statistics monitoring tool that displays performance statistics of a given JVM process with a specified sampling interval. "jstat" tool is distributed as part of the JDK package and represented by the \Progra~1\java\jdk*\bin\jstat.exe program file. "jstat" can be executed with the following syntax:

"jstatd": A server that allows JVM monitoring tools like "jps" and "jstat" to access JVM processes from a remote machine. "jstatd" tool is distributed as part of the JDK package and represented by the \Progra~1\java\jdk*\bin\jstatd.exe program file. "jstatd" can be executed with the following syntax:

"jvisualvm (Java Java VisualVM)": Java VisualVM is a tool that provides a visual interface for viewing detailed information about Java applications while they are running on a Java Virtual Machine (JVM), and for troubleshooting and profiling these applications. Java VisualVM federates previously standalone tools like JConsole, jstat, jinfo, jstack, and jmap to obtain data from the JVM software, then re-organizes and presents the information graphically, to enable you to view different data about multiple Java applications uniformly, whether they are running locally or on remote machines.

"JVM (Java Virtual Machine)": A software that simulates a central process unit (Virtual Machine) to run compiled Java code.

"keystore": A database used by JDK "keytool" command and KeyStore class to store your own private keys, and public key certificates you received from someone else. "keystore" supports the following features.

"keytool": A command line tool introduced in JDK 1.2 to manage keys and certificates using "keystore". "keytool" replaces the same functions offered by "javakey" in JDK 1.1. "keytool" offers a number functions through the following major command options.

native2ascii: Native-to-ASCII Encoding Converter - A command line tool that reads a text file stored in a non-ASCII encoding and converts it to an ASCII text file. All non-ASCII characters will be converted into \udddd sequences, where dddd is the Unicode code value of the non-ASCII character.

ZIP: A file format is a popular data compression and archival format. A ZIP file contains one or more files that have been compressed or stored.

The format was originally designed by Phil Katz for PKZIP. However, many software utilities other than PKZIP itself are now available to create, modify or open ZIP files, notably WinZip, BOMArchiveHelper, PicoZip, Info-ZIP, WinRAR and 7-Zip. Microsoft has also included minimal ZIP support (under the name "compressed folders") in later versions of its Windows operating system.

Last update: 2015.

Table of Contents

 About This Book

Java Tools Terminology

 Installing Java 8 on Windows

 'javac' - The Java Program Compiler

 'java' - The Java Program Launcher

 'jdb' - The Java Debugger

 'jconsole' - Java Monitoring and Management Console

 'jstat' - JVM Statistics Monitoring Tool

 JVM Troubleshooting Tools

 jvisualvm (Java VisualVM) - JVM Visual Tool

 'jar' - The JAR File Tool

 'javap' - The Java Class File Disassembler

 'keytool' - Public Key Certificate Tool

 'native2ascii' - Native-to-ASCII Encoding Converter

 Outdated Tutorials

 References

 PDF Printing Version