Jenkins script to update the JDK for all jobs

update-all-jenkins-jobs-jdks.groovy

import hudson.model.* 

String  newJdkName = "JDK 1.7.0_80"
boolean dryRun = true

def h = Hudson.getInstance() 
Set jdks = new HashSet()
def newJdk = h.getJDK(newJdkName)
assert newJdk, "unable to find a configured jdk named ${newJdkName}"

println "reconfiguring all jobs to use jdk '${newJdkName}'"
for (item in h.items) {
    if ( item instanceof com.cloudbees.hudson.plugins.folder.Folder ) {
        continue
    }
  
    if ( item.JDK?.name != newJdkName ) {
        println "\t job '${item.name}' current jdk '${item.JDK?.name}'"
        if (!dryRun) {
            item.setJDK(newJdk)
        }
    }
}