Enable Compile on Save option in Netbeans 11

Question

How can I enable Compile on Save in Apache Netbeans IDE 11.0?

Output of my java -version

java version "11.0.4" 2019-07-16 LTS
Java(TM) SE Runtime Environment 18.9 (build 11.0.4+10-LTS)
Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.4+10-LTS, mixed mode)

I tried setting:

• compile.on.save=true in nbproject/private/private.properties

• compile.on.save=true in nbproject/private.properties

• compile.on.save.unsupported.javafx=true in nbproject/private.properties

• compile.on.save.unsupported.javafx=false in nbproject/private.properties

and possible combinations of these. But not to succeed so far.

Answer 1

TLDR:

• You need to install the nb-javac library to enable compile on save.
• However, due to a NetBeans bug, you must use version 11.2 beta 3 of NetBeans for that to work.

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You may be seeing this issue because you need to install the nb-javac library. To determine whether installation is necessary:

• Open the Notifications window by selecting Window > IDE Tools > Notifications.

• If installation is required there will be a message stating "Install nb-javac Library" in the Notifications window:

  

To install the nb-javac library:

• Unfortunately you must use version 11.2 beta 3 (or later) of NetBeans. This is due to an unrelated problem with the installation of nb-javac.
• You can download NetBeans 11.2 beta 3 from this page. The file is named netbeans-11.2-beta3-bin.zip. Just download the zip file, then unzip it in a new directory.
• From version 11.2 beta 3 of NetBeans (or later), select the notification in the Notifications window.
• Click the link in the right pane with the text "It is recommended to install nb-javac Library to improve Java editing experience and enable compile on save".

• A wizard for installing the library will be shown:

  

• Complete the steps in the wizard. Once installation is complete, restart NetBeans.

After restarting NetBeans you should find that:

• The nb-javac library has been installed.
• The Compile on Save checkbox for your project is enabled.

I could reproduce your problem in NetBeans 11.1, and I have verified that this solution worked for me.

Notes:

• See Bug Report NETBEANS-2552 Fail to install nb-javac Library on NetBeans 11 for details on why you need to upgrade NetBeans to version 11.2 beta 3 to fix this issue.
• If you prefer not to use a beta release, version 11.2 of NetBeans should be available very soon.
• See these articles for further information on nb-javac:
  • "What's "nb-javac" in Apache NetBeans?".
  • Overview: nb-javac

Answer 2

The nbjavac plugin needs to be installed. See also here.