It’s hard to find old versions of Java on Sun’s website. So it may be worthwhile for a Linux/Unix administrator to keep old copies at hand. Also, keeping several versions installed is relatively easy — once you know the version of Java you want.

Different Versions to Install

The Linux versions of JDK come in several forms. There’s the 32-bit and 64-bit version. For each of these, there’s the .bin version and the rpm.bin version.

Installing the .bin version is very easy. Just run the jdk--linux-i586.bin or the jdk--linux-amd64.bin file as root. Agree to Sun’s legal jargon, and it will create a version-specific jdk folder in your current directory. Move it anywhere you please (i.e. /usr/local/jdk).

Installing from RPM

Since I’m using a Red Hat Linux machine, I’ll go into detailed instructions for the rpm install. I’m upgrading from JDK 1.5.0_12 to JDK 1.5.0_16. J2SE 5.0 is reaching its end-of-life (EOL), but that’s a different story.

For this install, I’ll place the various versions of java in /usr/local/jdk

1) Download the correct version of Java. I’m using a 64-bit machine, so I downloaded jdk-1_5_0_16-linux-amd64-rpm.bin. If you’re using a 32-bit machine, it’d probably be labeled jdk-1_5_0_16-linux-i586.rpm.bin. I like to keep a copy in /usr/local/src.

2) Check your current version of Java

which java


java -version

3) Set up your Java as a set of links, as follows:

ls /usr/bin/java

lrwxrwxrwx … /usr/bin/java -> /usr/local/java/bin/java

ls -l /usr/local/java

lrwxrwxrwx … /usr/local/java -> jdk1.5.0_12

4) Validate, install package in /usr/local, and verify your installation

cd /usr/local/src

rpm –checksig jdk-1_5_0_16-linux-amd64.rpm

mkdir /usr/java

rpm -i –relocate /usr/java=/usr/local jdk-1_5_0_16-amd64.rpm

rpm -q jdk

See the files associated with your jdk install

rpm -ql jdk

5) Point your default Java executable to your new install

cd /usr/local

rm java

ln -s jdk1.5.0_16 java

ls -l java

java -version