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java command line tools (java, javac, jar)

javac used to compile source files (*.java)
javac [-options] files
java used to run a compiled code (*.class)
java [-options] class [args...]
jar used to archive files into JAR (*.jar)
jar {ctxui}[vfm0Me] [jar-file] [manifest-file] [entry-point] [-C dir] files
In practise:
Source for Hello.java
package com.blogspot.programmerutilities;

public class Hello {

 public static void main (String[] args){
  System.out.println("Hello World!");
 }
}
Location of the file:
\src\com\blogspot\programmerutilities\Hello.java
Directory structure:
-src
   -com
      -blogspot
         -programmerutilities
            -Hello.java
-build
Compile source file using javac (-d option points to a directory where compiled files will be placed)
javac -d build \src\com\blogspot\programmerutilities\Hello.java
After compilation a Hello.class file will be placed in \build directory (and subdirectories accordingly to the package name).
-src
   -com
      -blogspot
         -programmerutilities
            -Hello.java
-build
   -com
      -blogspot
         -programmerutilities
            -Hello.class
To start this application go to \build (the directory directly above the outer directory of the package) and run java tool with a full name of the class (package and class name without an extension) 
cd build
java com.blogspot.programmerutilities.Hello
// Prints "Hello World!"
To create java archive (JAR) run jar tool with a name of new created archive (hello.jar) and the most outer directory of the package name (com)
jar -cf hello.jar com
After that in \build directory the hello.jar file will be placed
-src
   -com
      -blogspot
         -programmerutilities
            -Hello.java
-build
   -com
      -blogspot
         -programmerutilities
            -Hello.class
   -hello.jar
To check the content of the jar run jar tool with -tf options (table of content and file name)
jar -tf hello.jar
To start an application using a jar file run java tool with -cp (or -classpath) option with a path to a jar and full name of a class
java -cp /build/hello.jar com.blogspot.programmerutilities.Hello
// Prints "Hello World!"

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