Jenkins is an open source automation server that can be used to configure Continuous Integration for projects written in many programming languages. Let's consider the case of an application that is Java-based.

We need to tell Jenkins where Java is installed.

Download the required Java version based on the requirements of an application, or install automatically.

1. Open the Jenkins dashboard.
2. Go to Manage Jenkins.
3. Go to Global Tool Configuration to configure tools, their locations, and automatic installers.
4. Go to the JDK section.
5. Give the Name and tick the Install automatically option; provide details for the Oracle account to download JDK successfully.
6. You can give a logical name such as JDK 1.7 or JDK 1.8 to identify the correct version while configuring a build job.
7. You can add multiple JDKs based on the version, so if different applications require different JDKs then the scenario can be managed easily by adding JDK in Jenkins:

When you create a build job in Jenkins and configure it, you need to specify the Java version that will be used by the build execution. You can use existing Java available on the system as well if you don't want to install automatically.

In the general section of the build job, we can select a JDK from the list. This list contains all the JDKs that we have configured in the Global Tool Configuration.