Updating to the latest Java™ version ensures that
your Liberty environment receives new
features and security fixes.
About this task
Liberty can run with any compliant Java runtime environment (JRE) or Java software development kit (SDK). This flexibility means that you have several options for
installing the JRE or Java SDK:
Note:
Liberty on the IBM i platform uses the
system-wide version of Java. To install Java on IBM i, follow
these guidelines:
For more information, see
Installing Java on your IBM i
server.
Important: Removal notices were issued for Java SE 8 and 11, which means that support for these Java versions is removed as of the fix pack that is specified in
Removal notices. After support is removed, the
Liberty kernel is recompiled and can no longer
run with the removed Java version.
Procedure
-
Update your Liberty installation to at
least the minimum fix pack that supports the Java version. The more recent the fix pack, the more
features and fixes are included.
-
Update the JRE or Java SDK by using one of the following
options.
- If you installed Liberty
from the .zip file with IBM
Java SDK 8, you also received the latest Java updates. If you previously installed Liberty from this file and want to independently
update the Java SDK, download a newer version from IBM Java SDKs for WebSphere Liberty.
- If you installed Liberty by using
Installation Manager, you can also use it to install and update IBM
Java SDKs. If you use IBM
Java, install one of the common IBM
Java SDKs, such as IBM SDK, Java Technology Edition, Version 8. The
IBM SDKs receive security updates faster than the older WebSphere
Java SDKs because they are not on the WebSphere fix pack schedule. The IBM
Java 8 SDK is also used by WebSphere Application Server traditional V9.0.
For more
information about installing IBM
Java SDKs by using Installation Manager, see Installing, updating, and uninstalling IBM SDK, Java Technology
Edition.
- Install a separately downloaded JRE or Java SDK. You can
install any specification-compliant JRE or Java SDK of a
supported Java version.
After you install the JRE or Java SDK, change the Java
level that
Liberty uses by setting the
JAVA_HOME
variable.
Tip: You can specify the Java SDK or JRE location on the
JAVA_HOME
property in the
server.env file, as described in
Customizing the Liberty environment. When you set the
JAVA_HOME
property in the
server.env file,
Liberty uses the same Java runtime location regardless of the user profile that the
Liberty server runs under.
Alternatively,
you can set the
JAVA_HOME
variable on your operating system:
Go to . In the Advanced tab of the System Properties window, click Environment
Variables. Add or edit the JAVA_HOME
system variable so that it points
to the jre directory of the Java
installation, such as C:\Program Files\IBM\Java80\jre.
If you are running bash shell, you can add the
JAVA_HOME
environment variable to the .bashrc file in the
user's home directory.
-
Check for any deprecations or incompatibilities by scanning your applications with the
Migration Toolkit.
In most cases, Java SE specifications are upwards
binary-compatible with previous Java SE versions except for
the incompatibilities and deprecations that are documented in the Oracle Compatibility Guide for JDK 8 and Java SE 7 and JDK 7 Compatibility.
The Migration Toolkit consists of two separate tools, the Migration Toolkit for Application
Binaries and the Eclipse-based WebSphere Application Server Migration Toolkit.
- The application binary scanner provides a detailed migration analysis report for your
application, so you can better understand the type and scope of changes that the application might
require.
- When you migrate your applications, the Eclipse-based Migration Toolkit provides quick fixes to
automatically update your source when possible and provides detailed help for items that must be
manually updated.