class-loader-demo/Notes01.txt at master · bzdgn/class-loader-demo · GitHub

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00) INTRO
*********

	source directory;
	*****************
	c:\classload\src\
	...............\com\levent\Helper.java
	...............\com\levent\Main.java

	classes directory;
	******************
	c:\classload\classes\

	javac -d classes -sourcepath src src\com\levent\Helper.java
	javac -d classes -sourcepath src src\com\levent\Main.java

	classes directory after 'javac' command;
	****************************************
	c:\classload\classes\
	...................\com\levent\Helper.class
	...................\com\levent\Main.class

	to run;
	*******
	c:\classload\

	1) global classpath;
	********************
	set CLASSPATH=classes

	java com.levent.Main

	2) classpath as a parameter;
	****************************
	java -cp classes com.levent.Main


	Multi ClassPath with -cp;
	*************************
	windows : java -cp classes;other_class_dir com.levent.Main
	unix    : java -cp classes:other_class_dir com.levent.Main

01) Create a .jar file and use it;
**********************************

Under c:\classload\classes

jar cvf helper.jar com\levent\Helper.class

move the jar to the c:\lib

move helper.jar ..\lib\

c:\classload\lib\
...............\helper.jar

Delete the helper class
cd c:\classload\
del classes\com\levent\Helper.class
rmdir classes\com\levent

If you try to run the Main.class again, ClassNotFoundException will be thrown;
******************************************************************************

c:\classload>java -cp classes com.pluralsight.Main
Exception in thread "main" java.lang.NoClassDefFoundError: com/levent/Helper
        at com.pluralsight.Main.main(Main.java:5)
Caused by: java.lang.ClassNotFoundException: com.levent.Helper
        at java.net.URLClassLoader.findClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        ... 1 more

c:\classload>java -cp classes;lib\helper.jar com.pluralsight.Main
Hello from helper