Difference between revisions of "Installing Java"

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== What is Java? What purpose does it serve? ==
 
== What is Java? What purpose does it serve? ==
 
==== Definition ====
 
==== Definition ====
"Java is a computer programming language that is concurrent, class-based, object-oriented, and specifically designed to have as few implementation dependencies as possible. It is intended to let application developers "write once, run anywhere" (WORA), meaning that code that runs on one platform does not need to be recompiled to run on another. "
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"Java is a programming language and computing platform first released by Sun Microsystems in 1995. There are lots of applications and websites that will not work unless you have Java installed, and more are created every day. Java is fast, secure, and reliable. From laptops to datacenters, game consoles to scientific supercomputers, cell phones to the Internet, Java is everywhere!" ([http://www.java.com/en/download/faq/whatis_java.xml Oracle page on Java])
 
== Installing java ==
 
== Installing java ==
==== Editing your make.conf ====
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==== Options ====
To tell portage that we would like it to pull java in the next time it is updated, we need to do the following:
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On Funtoo, there are several different java packages that you can emerge:
<console>
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* '''virtual/jre''' - When you emerge this, it pulls in the java runtime environment for your current profile.
##r## # ##b##nano /etc/portage/make.conf
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* '''virtual/jdk''' - When you emerge this, it pulls in the java development kit for your current profile.
</console>
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* '''dev-java/icedtea''' - A Gentoo-made binary of the IcedTea JDK, this is the JDK pulled in when you emerge '''virtual/jdk''' on the desktop profile.  
Running that command should present you with a file containing something similar to this:
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* '''dev-java/
[[File:Make conf example.png|thumbnail|left|An example make.conf]]
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In the file, if it does not exist, create a line like the following:
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<console>
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##b##USE="java"
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</console>
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Press Ctrl+X , then y, then enter to write the changes to the file.
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==== Emerging java ====
 
==== Emerging java ====
 
To install java, run the following command:
 
To install java, run the following command:
 
<console>
 
<console>
##r## # ##b##emerge --ask --update --newuse --deep @world
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##r## # ##b##emerge -av virtual/jdk
  
 
##g##These are the packages that would be merged, in order:
 
##g##These are the packages that would be merged, in order:
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java version "1.7.0_21"OpenJDK Runtime Environment (IcedTea 2.3.9) (Gentoo build 1.7.0_21-b02)OpenJDK 64-Bit Server VM (build 23.7-b01, mixed mode)
 
java version "1.7.0_21"OpenJDK Runtime Environment (IcedTea 2.3.9) (Gentoo build 1.7.0_21-b02)OpenJDK 64-Bit Server VM (build 23.7-b01, mixed mode)
 
</console>
 
</console>
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== Using the java command ==
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==== Overview of the command ====
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The java command can be run like so:
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* '''java [options] class [argument ...]'''
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* '''java [options] -jar file.jar [argument ...]'''
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 +
==== Example command usage ====
 +
Compiling code:
 +
<console>
 +
##bl##$ ##b##javac -d bin -sourcepath src -cp lib/lib1.jar;lib/lib2.jar src/com/example/Application.java
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</console>
 +
 +
Running code:
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<console>
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##bl##$ ##b##java -cp bin;lib/lib1.jar;lib/lib2.jar com.example.Application
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</console>
 +
 +
Running a jarfile:
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<console>
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##bl##$ ##b##java -jar Application.jar
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</console>
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== More Information ==
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* [http://docs.oracle.com/javase/ Java SE at Oracle.com]
 +
* [http://en.wikipedia.org/wiki/Java_(programming_language) Wikipedia article]
 +
* [http://docs.oracle.com/javase/tutorial/ Very informative tutorials]
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 +
== Sources ==
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([http://www.sergiy.ca/how-to-compile-and-launch-java-code-from-command-line/ Information provided for example command usage])
 +
 
[[Category:System]]
 
[[Category:System]]

Revision as of 19:20, 28 October 2013

What is Java? What purpose does it serve?

Definition

"Java is a programming language and computing platform first released by Sun Microsystems in 1995. There are lots of applications and websites that will not work unless you have Java installed, and more are created every day. Java is fast, secure, and reliable. From laptops to datacenters, game consoles to scientific supercomputers, cell phones to the Internet, Java is everywhere!" (Oracle page on Java)

Installing java

Options

On Funtoo, there are several different java packages that you can emerge:

  • virtual/jre - When you emerge this, it pulls in the java runtime environment for your current profile.
  • virtual/jdk - When you emerge this, it pulls in the java development kit for your current profile.
  • dev-java/icedtea - A Gentoo-made binary of the IcedTea JDK, this is the JDK pulled in when you emerge virtual/jdk on the desktop profile.
  • dev-java/

Emerging java

To install java, run the following command:

 # emerge -av virtual/jdk

These are the packages that would be merged, in order:

Calculating dependencies... done!
[ebuild  N     ] dev-java/java-config-wrapper-0.16  8 kB
[ebuild  N     ] sys-apps/baselayout-java-0.1.0  71 kB
[ebuild  N     ] dev-java/java-config-2.2.0-r1000:2  PYTHON_ABIS="2.7 3.3 -2.6 -3.1 -3.2 (-3.4)" 51 kB
[ebuild  N     ] app-admin/eselect-java-0.1.0  71 kB
[ebuild  N     ] dev-java/icedtea-bin-7.2.3.9:7  USE="X alsa cups -cjk -doc -examples -nsplugin -source" 47,781 kB
[ebuild  N     ] virtual/jdk-1.7.0:1.7  0 kB
[ebuild  N     ] virtual/jre-1.7.0:1.7  0 kB
Would you like to merge these packages? [Yes/No] yes

Testing to see if it emerged

To check that java installed on your system, run the following command:

java -version

If you get something like this, you are ready to use java!:

java version "1.7.0_21"OpenJDK Runtime Environment (IcedTea 2.3.9) (Gentoo build 1.7.0_21-b02)OpenJDK 64-Bit Server VM (build 23.7-b01, mixed mode)

Using the java command

Overview of the command

The java command can be run like so:

  • java [options] class [argument ...]
  • java [options] -jar file.jar [argument ...]

Example command usage

Compiling code:

$ javac -d bin -sourcepath src -cp lib/lib1.jar;lib/lib2.jar src/com/example/Application.java

Running code:

$ java -cp bin;lib/lib1.jar;lib/lib2.jar com.example.Application

Running a jarfile:

$ java -jar Application.jar

More Information

Sources

(Information provided for example command usage)