Java Tools Tutorials - Herong's Tutorial Examples - v6.24, by Herong Yang
Using JAR Files in Java Class Paths
This section provides a tutorial example on how to use JAR files in class paths during Java compilation and execution time.
One advantage of aggregating individual class files into a JAR file is that other Java tools recognize JAR files as collections of class files and allow you to use them in the class path.
For example, I can specify "-classpath herong.jar" when using "javac" and "java" commands to compile and run Java program that uses the "com.herongyang.TempratureConvertorBean" class stored in the JAR file.
To test this idea, I created this class, F2C.java:
/* F2C.java * Copyright (c) 2005 HerongYang.com. All Rights Reserved. */ import com.herongyang.TempratureConvertorBean; public class F2C { public static void main(String[] arg) { TempratureConvertorBean b = new TempratureConvertorBean(); double f = 0.0; if (arg.length>0) f = Double.parseDouble(arg[0]); b.setFahrenheit(f); double c = b.getCelsius(); System.out.println("Fahrenheit = "+f); System.out.println("Celsius = "+c); System.out.println(b.getInfo()); } }
Here is what I did to test the above program using herong.jar in the class path:
herong> javac -classpath herong.jar F2C.java herong> java -classpath .;herong.jar F2C 70.0 Fahrenheit = 70.0 Celsius = 21.11111111111111 My TempraturConvertorBean - Version 1.00
This is nice. Right? I can take herong.jar to anywhere on any system. Just add it to "-classpath" for "javac" command, and "-cp" for "java" command.
Table of Contents
javac - The Java Program Compiler
java - The Java Program Launcher
JAR - Java Archive File Format
jar - JAR File Tool Command and Options
"jar --create" - Creating New JAR File
"jar --list" - Listing Files in JAR File
"jar --extract" - Extracting Files from JAR File
Managing JAR Files with WinZIP
META-INF/MANIFEST.MF - JAR Manifest File
Adding META-INF/MANIFEST.MF to JAR Files
"jar -C" - Changing Input Directory
►Using JAR Files in Java Class Paths
"jar --update" - Updating Class Files in JAR
"jar --main-class" - Making JAR File Executable
"jar --module-version" - Updating Module Version in JAR
jpackage - Binary Package Builder
javadoc - The Java Document Generator
jdeps - The Java Class Dependency Analyzer
jdeprscan - The Java Deprecated API Scanner
jcmd - The JVM Diagnostic Tool
jconsole - Java Monitoring and Management Console
jstat - JVM Statistics Monitoring Tool
jhsdb - The Java HotSpot Debugger
jvisualvm (Java VisualVM) - JVM Visual Tool
javap - The Java Class File Disassembler
keytool - Public Key Certificate Tool
jrunscript - Script Code Shell
native2ascii - Native-to-ASCII Encoding Converter