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javaeclipsejava-15

Eclipse Java 15 support not working, compiler does not show correct version

I have followed the steps in https://marketplace.eclipse.org/content/java-15-support-eclipse-2020-09-417 to install the Java 15 support for Eclipse after previously upgrading my Eclipse to 2020-12 (4.18.0). However it doesn't work (compiler not showing version above 12), and build path does not recognize a JDK 15 when added manually:

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I wonder if the small red plus icon next to the Java 15 plugin in the third screenshot means anything.

Any help is appreciated.

Solution

  • In your last screenshot, the two items whose version ends with _JAVA15_PATCH should not be there and the Eclipse Java Development Tools is too old (according to the version number ...v201906..., released June 2019 instead of December 2020) to support Java up to version 15.

    To get Java 15 support, update the Java Development Tools (JDT):

    1. In the Eclipse IDE Installation Details dialog select the two items whose version ends with _JAVA15_PATCH and click Uninstall... (they might prevent updating JDT)
    2. In Window > Preferences: Install/Update > Available Software Sites add the update site http://download.eclipse.org/releases/latest if it not yet exists
    3. Run Help > Check for Updates to update JDT