Java common system and method for obtaining path

// delimiter
String fileSeperator = File.seperator;

// home directory
String USERHOME = System.getProperties () getProperty ( "user.home");.

// jre installation path of the Java
String javaPath = System.getProperties () .getProperty ( "java.home");

// operating system name
String OSNAME = System.getProperties () getProperty ( "os.name");.

// current user program directory
. String userDir = System.getProperties () getProperty ( "user.dir");

// the JDK installation directory
String jdkDir = System.getProperties () getProperty ( "java.ext.dirs").;