[ https://issues.jboss.org/browse/JBIDE-19049?page=com.atlassian.jira.plugi... ] Rob Stryker commented on JBIDE-19049: ------------------------------------- tl;dr: Mars is missing functionality for properly using Java 9. Because it's missing this functionality, the Java 9 jre/jdk is not marked as compatible with the minimum execution environment for the server, and cannot be used. If you go to window -> Preferences and type "Execution Environment" you will see that there is no JavaSE-1.9 execution environment. Theoretically, java 9 should also show up as valid for a j7 or j8 execution environment, but it's not. Tracing through when adding the jre/jdk to "Installed JREs", I see: {code} EnvironmentsManager.analyze(IVMInstall, IProgressMonitor) line: 342 EnvironmentsManager.vmAdded(IVMInstall) line: 380 JavaRuntime.fireVMAdded(IVMInstall) line: 2387 {code} I see the following code: {code} Analyzer[] analyzers = getAnalyzers(); for (int i = 0; i < analyzers.length; i++) { Analyzer analyzer = analyzers[i]; try { CompatibleEnvironment[] environments = analyzer.analyze(vm, monitor); {code} There is only 1 "analyzer", and there are 0 compatible environments for the given jdk / jre. Looking in ExecutionEnvironmentAnalyzer, we see the following code: {code} if (javaVersion.startsWith("1.8")) //$NON-NLS-1$ types = getTypes(JavaSE_1_8); else if (javaVersion.startsWith("1.7")) //$NON-NLS-1$ types = getTypes(JavaSE_1_7); else if (javaVersion.startsWith("1.6")) //$NON-NLS-1$ types = getTypes(JavaSE_1_6); else if (javaVersion.startsWith("1.5")) //$NON-NLS-1$ types = getTypes(J2SE_1_5); else if (javaVersion.startsWith("1.4")) //$NON-NLS-1$ types = getTypes(J2SE_1_4); else if (javaVersion.startsWith("1.3")) //$NON-NLS-1$ types = getTypes(J2SE_1_3); else if (javaVersion.startsWith("1.2")) //$NON-NLS-1$ types = getTypes(J2SE_1_2); else if (javaVersion.startsWith("1.1")) { //$NON-NLS-1$ if ((vm instanceof IVMInstall3) && isFoundation1_1((IVMInstall3) vm)) types = getTypes(CDC_FOUNDATION_1_1); else types = getTypes(JRE_1_1); } else if (javaVersion.startsWith("1.0")) { //$NON-NLS-1$ if ((vm instanceof IVMInstall3) && isFoundation1_0((IVMInstall3) vm)) types = getTypes(CDC_FOUNDATION_1_0); } {code} So basically, they're missing an if-statement for java9 as well as a constant for it etc. -- This message was sent by Atlassian JIRA (v6.3.11#6341)