As is by now well-known, Oracle changed the Java license in Java 11 to require paid licenses for commercial usage of the JDK. Yet to use OpenJDK is still free.
I have a JDK 11 folder on my PC that looks like this:
Is there a way somewhere in these folders to tell whether I have a free OpenJDK version or an Oracle JDK version that requires a paid license?
You see a file called release in the root directory of the JDK. Open it with a text editor and check whether it contains the line
BUILD_TYPE="commercial"
If so, well, then it’s a commercial build.
This is how it looks like for my installation of 11.0.1 OpenJDK:
IMPLEMENTOR="Oracle Corporation"
IMPLEMENTOR_VERSION="18.9"
JAVA_VERSION="11.0.1"
JAVA_VERSION_DATE="2018-10-16"
MODULES="java.base java.compiler java.datatransfer java.xml java.prefs java.desktop java.instrument java.logging java.management java.security.sasl java.naming java.rmi java.management.rmi java.net.http java.scripting java.security.jgss java.transaction.xa java.sql java.sql.rowset java.xml.crypto java.se java.smartcardio jdk.accessibility jdk.internal.vm.ci jdk.management jdk.unsupported jdk.internal.vm.compiler jdk.aot jdk.internal.jvmstat jdk.attach jdk.charsets jdk.compiler jdk.crypto.ec jdk.crypto.cryptoki jdk.crypto.mscapi jdk.dynalink jdk.internal.ed jdk.editpad jdk.hotspot.agent jdk.httpserver jdk.internal.le jdk.internal.opt jdk.internal.vm.compiler.management jdk.jartool jdk.javadoc jdk.jcmd jdk.management.agent jdk.jconsole jdk.jdeps jdk.jdwp.agent jdk.jdi jdk.jfr jdk.jlink jdk.jshell jdk.jsobject jdk.jstatd jdk.localedata jdk.management.jfr jdk.naming.dns jdk.naming.rmi jdk.net jdk.pack jdk.rmic jdk.scripting.nashorn jdk.scripting.nashorn.shell jdk.sctp jdk.security.auth jdk.security.jgss jdk.unsupported.desktop jdk.xml.dom jdk.zipfs"
OS_ARCH="x86_64"
OS_NAME="Windows"
SOURCE=".:8513ac27b651"
and for the equivalent Oracle JDK:
BUILD_TYPE="commercial"
IMPLEMENTOR="Oracle Corporation"
IMPLEMENTOR_VERSION="18.9"
JAVA_VERSION="11.0.1"
JAVA_VERSION_DATE="2018-10-16"
MODULES="java.base java.compiler java.datatransfer java.xml java.prefs java.desktop java.instrument java.logging java.management java.security.sasl java.naming java.rmi java.management.rmi java.net.http java.scripting java.security.jgss java.transaction.xa java.sql java.sql.rowset java.xml.crypto java.se java.smartcardio jdk.accessibility jdk.internal.vm.ci jdk.management jdk.unsupported jdk.internal.vm.compiler jdk.aot jdk.internal.jvmstat jdk.attach jdk.charsets jdk.compiler jdk.crypto.ec jdk.crypto.cryptoki jdk.crypto.mscapi jdk.dynalink jdk.internal.ed jdk.editpad jdk.hotspot.agent jdk.httpserver jdk.internal.le jdk.internal.opt jdk.internal.vm.compiler.management jdk.jartool jdk.javadoc jdk.jcmd jdk.management.agent jdk.jconsole jdk.jdeps jdk.jdwp.agent jdk.jdi jdk.jfr jdk.jlink jdk.jshell jdk.jsobject jdk.jstatd jdk.localedata jdk.management.jfr jdk.naming.dns jdk.naming.rmi jdk.net jdk.pack jdk.rmic jdk.scripting.nashorn jdk.scripting.nashorn.shell jdk.sctp jdk.security.auth jdk.security.jgss jdk.unsupported.desktop jdk.xml.dom jdk.zipfs"
OS_ARCH="x86_64"
OS_NAME="Windows"
SOURCE=".:657c1504057c open:8513ac27b651"
So besides the “commercial” line, it names another source repository. Which makes sense considering that it has some additional features.
You may also open one of the .h files in the include directory and look at the header. The commercial version’s header start with
/*
* Copyright (c) 1999, 2017, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*/
whereas the free version starts with
/*
* Copyright (c) 1999, 2017, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
The same difference applies to all .java files in the lib/src.zip archive, but extracting them is not necessarily a “quick check” anymore.