UbuntuにJAVAをインストール

Ubuntuにソフトをインストールする作法がいまいち理解出来ていない

UbuntuにJAVAをインストール

資料
http://www.wikihow.com/Install-Oracle-Java-on-Ubuntu-Linux
以下は資料のページのコピー

1
Let's check if you have Java installed on your system by running the Java version command from terminal.

2
Open up a terminal and type the command:

Type/Copy/Paste: java -version
If it says anything such as OpenJDK, you have the wrong Java installed for this exercise, we want it to display:

java version "1.7.0"
Java(TM) SE Runtime Environment (build 1.7.0-b147)
Java HotSpot(TM) 64-Bit Server VM (build 21.0-b17, mixed mode)

3
If you have the OpenJDK installed on your system you can remove it by typing the following at the command line:

Type/Copy/Paste: sudo apt-get autoremove openjdk-6-jre
Type/Copy/Paste: sudo apt-get autoremove openjdk-6-jdk

4
Create a directory to put your Oracle Java JDK and JRE binaries in, open up a terminal and create the directory /usr/local/java

Type/Copy/Paste: sudo mkdir -p /usr/local/java

5
Download the Oracle Java JDK/JRE for Linux, make sure you select the compressed binaries for your system which end in tar.gz
6
Change into the directory where the Oracle Java binaries were downloaded and move them into the /usr/local/java directory. For example, in most cases the Oracle Java binaries are downloaded to: /home/"your_user_directory"/Downloads

Type/Copy/Paste: sudo -s
Type/Copy/Paste: cd /home/"your_user_directory"/Downloads
Type/Copy/Paste: cp -r jdk-7-linux-x64.tar.gz /usr/local/java
Type/Copy/Paste: cp -r jre-7-linux-x64.tar.gz /usr/local/java
Type/Copy/Paste: cd /usr/local/java

7
Run the following commands on the downloaded Oracle Java tar.gz files, as root, in order to make them executable for all users on your system.

Type/Copy/Paste: sudo chmod a+x jdk-7-linux-x64.tar.gz
Type/Copy/Paste: sudo chmod a+x jre-7-linux-x64.tar.gz

8
Unpack the compressed java binaries, in the directory /usr/local/java

Type/Copy/Paste: tar xvzf jdk-7-linux-x64.tar.gz
Type/Copy/Paste: tar xvzf jre-7-linux-x64.tar.gz

9
At this point you should have two uncompressed binary directories in /usr/local/java for the Java JDK/JRE listed as:

jdk1.7.0
jre1.7.0

10
Edit the system PATH file /etc/profile and add the following system variables to your system path. Use nano, gedit or any other text editor, as root, and open up /etc/profile

Type/Copy/Paste: sudo nano /etc/profile
or
Type/Copy/Paste: sudo gedit /etc/profile

11
Scroll down using your arrow keys to the end of the file and add the following lines below to the end of your /etc/profile file in Ubuntu Linux:
12
Type/Copy/Paste:

JAVA_HOME=/usr/local/java/jdk1.7.0
PATH=$PATH:$HOME/bin:$JAVA_HOME/bin
JAVA_HOME=/usr/local/java/jre1.7.0
PATH=$PATH:$HOME/bin:$JAVA_HOME/bin
export JAVA_HOME
export JAVA_BIN
export PATH

13
Save the file and exit.
14
Inform your Ubuntu Linux system where your Oracle Java JDK/JRE is located, now you will want to tell the system Oracle Java 1.7.0 version is available for use.

Type/Copy/Paste: sudo update-alternatives --install "/usr/bin/java" "java" "/usr/local/java/jre1.7.0/bin/java" 1
Type/Copy/Paste: sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/local/java/jdk1.7.0/bin/javac" 1

15
Inform your Ubuntu Linux system, that Oracle Java JDK/JRE must be the default Java.

Type/Copy/Paste: sudo update-alternatives --set java /usr/local/java/jre1.7.0/bin/java
Type/Copy/Paste: sudo update-alternatives --set javac /usr/local/java/jdk1.7.0/bin/javac

16
Also reload your system wide PATH /etc/profile by typing the following command:
17
Type/Copy/Paste: . /etc/profile

Note your system wide PATH /etc/profile file will reload after reboot of your Ubuntu Linux system

18
You can test to see if Oracle Java was installed correctly on your system by running the following commands and noting the version of Java
19
Type/Copy/Paste: java -version

this command displays the version of java running on your system

20
You should receive a message which displays:

java version "1.7.0"
Java(TM) SE Runtime Environment (build 1.7.0-b147)Java HotSpot(TM) 64-Bit Server VM (build 21.0-b17, mixed mode)

21
Type/Copy/Paste: javac -version

this command lets you know that you are now able to compile java programs from the terminal

22
You should receive a message which displays:

javac 1.7.0

23
Now, reboot your Ubuntu Linux system and your system will be fully configured for running and developing Java programs.