Where can we get the source files for Java packages (such as java/lang/Integer.java)?

• Java Archive files

  Java source files can be downloaded from Sun. There are archived in "jar" files. For instance, the file "src.jar" contains all the sources for the basic language.

• Looking at what is in a jar file

  On unix machines, you can list all the files in src.jar by doing

  	% jar -tvf src.jar
  
  		-- the list of files is very very long
  
  	% jar -tvf src.jar src/java/lang
  
  		-- list only the files under src/java/lang
  	

• How to extract files from a jar file

  To extract the files in src.jar:

  	% jar -xvf src.jar src/java/lang/Integer.java
  
  		-- the extracted file "Integer.java" will
  		   have the correct directory structure
  	
  	% jar -xvf src.jar src/java/lang/
  
  		-- extracts everything under src/java/lang