3. Installing Java
Download the latest versions of the
Java 2 Development Kit
(JDK) or
Run-time Engine
(JRE),
and the accompanying documentation from:
Installation instructions and release notes for the
JDK and
JRE
are available at the download page.
Make the binary distribution of the
JDK
executable
and extract in a new directory:
chmod +x jdk-xxx.bin
cd /usr/local/
.../jdk-xxx.bin
|
Install the JDK
documentation
by unzipping it in the
JDK directory:
cd /usr/local/jdk-xxx/
unzip .../jdk-xxx-doc.zip
|
Change the ownership of the
JDK directory
and make it available as
/usr/local/j2sdk/:
chown -R root:root /usr/local/jdk-xxx/
ln -s /usr/local/jdk-xxx /usr/local/j2sdk
|
If you need only the
JRE,
the installation would be like this:
chmod +x jre-xxx.bin
cd /usr/local/
.../jre-xxx.bin
chown -R root:root /usr/local/jre-xxx/
ln -s /usr/local/jre-xxx /usr/local/j2re
|
 |
Using JDK
version 1.5.0 caused
our Tomcat server
to crash every now and then:
#
# An unexpected error has been detected by HotSpot Virtual Machine:
#
# SIGSEGV (0xb) at pc=0x4042db3f, pid=11991, tid=16386
#
# Java VM: Java HotSpot(TM) Server VM (1.5.0-b64 mixed mode)
# Problematic frame:
# V [libjvm.so+0x3abb3f]
#
|
Upgrading to version 1.5.0-01 seemed to solve these problems.
|
 |
For the (previously used)
BlackDown Java for Linux distribution:
Find yourself a mirror for the
BlackDown Java Development Kit
at:
There you can download the latest versions of the
J2 Software Development Kit (SDK)
and
Run-time Engine (RE).
Make sure you pick out the right version for the
gcc library installed on your system.
You can find out the version currently installed by typing:
Installation instructions for the
Java Development Kit
are available as
INSTALL-j2sdk
and INSTALL-j2re.
Make the binary distribution of the
SDK
executable
and extract in a new directory:
chmod +x j2sdk-xxx.bin
cd /usr/local/
.../j2sdk-xxx.bin
|
Change the ownership of the
J2SDK
directory
and make it available as
/usr/local/j2sdk/:
chown -R root:root /usr/local/j2sdk-xxx/
ln -s /usr/local/j2sdk-xxx /usr/local/j2sdk
|
Do the same for the
RE:
chmod +x j2re-xxx.bin
cd /usr/local/
.../j2re-xxx.bin
chown -R root:root /usr/local/j2re-xxx/
ln -s /usr/local/j2re-xxx /usr/local/j2re
|
|
Since we didn't install the
JDK
and JRE
in our path,
we have to add the bin/ directories
to our $PATH environment variable.
To make sure the Java
distributions and classes can be found,
we set the $JAVA_HOME
and $CLASSPATH variables as well.
For the Bourne shells,
create a file /etc/profile.d/java.sh:
if ! echo ${PATH} | grep -q /usr/local/j2sdk/bin ; then
export PATH=/usr/local/j2sdk/bin:${PATH}
fi
if ! echo ${PATH} | grep -q /usr/local/j2re/bin ; then
export PATH=/usr/local/j2re/bin:${PATH}
fi
export JAVA_HOME=/usr/local/j2sdk
export CLASSPATH=.:/usr/local/j2sdk/lib/tools.jar:/usr/local/j2re/lib/rt.jar
|
Set its ownership and access rights:
chown root:root /etc/profile.d/java.sh
chmod 755 /etc/profile.d/java.sh
|
Do the same for C shells,
by creating the file
/etc/profile.d/java.csh:
if ( "${path}" !~ */usr/local/j2sdk/bin* ) then
set path = ( /usr/local/j2sdk/bin $path )
endif
if ( "${path}" !~ */usr/local/j2re/bin* ) then
set path = ( /usr/local/j2re/bin $path )
endif
setenv JAVA_HOME /usr/local/j2sdk
setenv CLASSPATH .:/usr/local/j2sdk/lib/tools.jar:/usr/local/j2re/lib/rt.jar
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and setting its ownership and access rights:
chown root:root /etc/profile.d/java.csh
chmod 755 /etc/profile.d/java.csh
|
Now the JDK
should be available to everyone on your system.
 |
You can test the Java engine
by typing:
or create a file Test.java:
public class Test {
public static void main(String[] args) {
System.out.println("Hello world");
}
}
|
and test the compiler:
javac Test.java
java Test
|
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