MMBase Installation HOWTO
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3. Installing Java

Download the latest versions of the Java 2 Development Kit (JDK) or Run-time Engine (JRE), and the accompanying documentation from:
http://java.sun.com

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:
http://www.blackdown.org/java-linux/mirrors.html

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:
rpm -q libgcc

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

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:
java -version

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