How can I know which radio button is selected in Jenkins?

My code example:

<f:section title="Select or upload application file">
   <f:radioBlock checked="true" name="file" value="" title="Upload new version" inline="true">
      <f:entry title="File Path" field="appFile">
         <f:textbox/>
      </f:entry>
      <f:entry title="New Version" field="newVersion">
         <f:textbox/>
      </f:entry>
   </f:radioBlock>
   <f:radioBlock checked="false" name="file" value="" title="Available versions" inline="true">
      <f:entry title="" field="oldVersion">
         <f:select/>
      </f:entry>
   </f:radioBlock>
</f:section>

Solution

A good place to start with this is to look for other plugins.

The jelly here looks like this

<f:radioBlock name="testToRun" value="BUILTIN_FUZZ" checked="${instance.isTestType('BUILTIN_FUZZ')}" title="Built-in Fuzz" inline="true">
  <f:nested>
    <f:entry title="Event Count" field="eventCount" description="[Optional] Number of fuzz events.">
      <f:textbox/>
    </f:entry>
    <f:entry title="Event Throttle" field="eventThrottle" description="[Optional] Number for event throttle.">
      <f:textbox/>
    </f:entry>
    <f:entry title="Seed" field="seed" description="[Optional] Seed to use for randomizing events.">
      <f:textbox/>
    </f:entry>
  </f:nested>
</f:radioBlock>

which uses the function defined here

public String isTestType(String testTypeName) {
    return this.testToRun.equalsIgnoreCase(testTypeName) ? "true" : "";
}

You need to bind the checked property to something in the instance

checked="${instance.isTestType('BUILTIN_FUZZ')}"

and have a public property on the class

public String testToRun;

and add that field into the DataBoundConstructor

@DataBoundConstructor
@SuppressWarnings("unused")
public AWSDeviceFarmRecorder(String projectName,
                             String devicePoolName,
                             String appArtifact,
                             String testToRun,

and you already have

inline="true"

so you don't have to add inner classes with its own DataBoundConstructor.