Simply follow the documentation: http://docs.gluonhq.com/javafxports/
Could be a problem with your JRE or Android SDK version.

Requested project: C:\Users\anu\Documents\NetBeansProjects\net

Stack trace:
org.gradle.tooling.BuildException: Could not execute build using Gradle distribution 'https://services.gradle.org/distributions/gradle-2.2.1-all.zip'.
at org.gradle.tooling.internal.consumer.ResultHandlerAdapter.onFailure(ResultHandlerAdapter.java:59)
at org.gradle.tooling.internal.consumer.async.DefaultAsyncConsumerActionExecutor$1$1.run(DefaultAsyncConsumerActionExecutor.java:57)
at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:54)
at org.gradle.internal.concurrent.StoppableExecutorImpl$1.run(StoppableExecutorImpl.java:40)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
at org.gradle.tooling.internal.consumer.BlockingResultHandler.getResult(BlockingResultHandler.java:46)
at org.gradle.tooling.internal.consumer.DefaultBuildLauncher.run(DefaultBuildLauncher.java:72)
at org.netbeans.gradle.project.tasks.AsyncGradleTask.runBuild(AsyncGradleTask.java:369)
at org.netbeans.gradle.project.tasks.AsyncGradleTask.doGradleTasksWithProgressIgnoreTaskDefCancel(AsyncGradleTask.java:492)
at org.netbeans.gradle.project.tasks.AsyncGradleTask.doGradleTasksWithProgressIgnoreTaskDefCancel(AsyncGradleTask.java:402)
at org.netbeans.gradle.project.tasks.AsyncGradleTask.doGradleTasksWithProgress(AsyncGradleTask.java:393)
at org.netbeans.gradle.project.tasks.AsyncGradleTask.access$400(AsyncGradleTask.java:84)
at org.netbeans.gradle.project.tasks.AsyncGradleTask$BuildExecutionItem$1.run(AsyncGradleTask.java:775)
at org.netbeans.gradle.project.tasks.GradleDaemonManager.runBlockingGradleTask(GradleDaemonManager.java:52)
at org.netbeans.gradle.project.tasks.GradleDaemonManager.access$200(GradleDaemonManager.java:23)
at org.netbeans.gradle.project.tasks.GradleDaemonManager$2.execute(GradleDaemonManager.java:129)
at org.jtrim.concurrent.AbstractTaskExecutorService$FunctionWrapper.execute(AbstractTaskExecutorService.java:270)
at org.jtrim.concurrent.AbstractTaskExecutorService$TaskOfAbstractExecutor.execute(AbstractTaskExecutorService.java:340)
at org.jtrim.concurrent.Tasks$RunOnceCancelableTask.execute(Tasks.java:342)
at org.jtrim.concurrent.ThreadPoolTaskExecutor$ThreadPoolTaskExecutorImpl$QueuedItem.runTask(ThreadPoolTaskExecutor.java:1213)
at org.jtrim.concurrent.ThreadPoolTaskExecutor$ThreadPoolTaskExecutorImpl$Worker.executeTask(ThreadPoolTaskExecutor.java:1049)
at org.jtrim.concurrent.ThreadPoolTaskExecutor$ThreadPoolTaskExecutorImpl$Worker.run(ThreadPoolTaskExecutor.java:1179)
at org.jtrim.concurrent.ThreadPoolTaskExecutor$ThreadPoolTaskExecutorImpl$Worker$1.run(ThreadPoolTaskExecutor.java:998)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.gradle.internal.exceptions.LocationAwareException: Execution failed for task ':dex'.
at org.gradle.initialization.DefaultExceptionAnalyser.transform(DefaultExceptionAnalyser.java:77)
at org.gradle.initialization.MultipleBuildFailuresExceptionAnalyser.transform(MultipleBuildFailuresExceptionAnalyser.java:47)
at org.gradle.initialization.StackTraceSanitizingExceptionAnalyser.transform(StackTraceSanitizingExceptionAnalyser.java:30)
at org.gradle.initialization.DefaultGradleLauncher.doBuild(DefaultGradleLauncher.java:108)
at org.gradle.initialization.DefaultGradleLauncher.run(DefaultGradleLauncher.java:86)
at org.gradle.launcher.exec.InProcessBuildActionExecuter$DefaultBuildController.run(InProcessBuildActionExecuter.java:80)
at org.gradle.tooling.internal.provider.BuildModelAction.run(BuildModelAction.java:43)
at org.gradle.tooling.internal.provider.BuildModelAction.run(BuildModelAction.java:30)
at org.gradle.tooling.internal.provider.ConfiguringBuildAction.run(ConfiguringBuildAction.java:119)
at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:36)
at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:26)
at org.gradle.launcher.daemon.server.exec.ExecuteBuild.doBuild(ExecuteBuild.java:47)
at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:34)
at org.gradle.launcher.daemon.server.exec.DaemonCommandExecution.proceed(DaemonCommandExecution.java:119)
at org.gradle.launcher.daemon.server.exec.WatchForDisconnection.execute(WatchForDisconnection.java:35)
at org.gradle.launcher.daemon.server.exec.DaemonCommandExecution.proceed(DaemonCommandExecution.java:119)
at org.gradle.launcher.daemon.server.exec.ResetDeprecationLogger.execute(ResetDeprecationLogger.java:24)
at org.gradle.launcher.daemon.server.exec.DaemonCommandExecution.proceed(DaemonCommandExecution.java:119)
at org.gradle.launcher.daemon.server.exec.StartStopIfBuildAndStop.execute(StartStopIfBuildAndStop.java:33)
at org.gradle.launcher.daemon.server.exec.DaemonCommandExecution.proceed(DaemonCommandExecution.java:119)
at org.gradle.launcher.daemon.server.exec.ForwardClientInput$2.call(ForwardClientInput.java:71)
at org.gradle.launcher.daemon.server.exec.ForwardClientInput$2.call(ForwardClientInput.java:69)
at org.gradle.util.Swapper.swap(Swapper.java:38)
at org.gradle.launcher.daemon.server.exec.ForwardClientInput.execute(ForwardClientInput.java:69)
at org.gradle.launcher.daemon.server.exec.DaemonCommandExecution.proceed(DaemonCommandExecution.java:119)
at org.gradle.launcher.daemon.server.exec.LogToClient.doBuild(LogToClient.java:60)
at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:34)
at org.gradle.launcher.daemon.server.exec.DaemonCommandExecution.proceed(DaemonCommandExecution.java:119)
at org.gradle.launcher.daemon.server.exec.EstablishBuildEnvironment.doBuild(EstablishBuildEnvironment.java:70)
at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:34)
at org.gradle.launcher.daemon.server.exec.DaemonCommandExecution.proceed(DaemonCommandExecution.java:119)
at org.gradle.launcher.daemon.server.exec.DaemonHygieneAction.execute(DaemonHygieneAction.java:39)
at org.gradle.launcher.daemon.server.exec.DaemonCommandExecution.proceed(DaemonCommandExecution.java:119)
at org.gradle.launcher.daemon.server.exec.StartBuildOrRespondWithBusy$1.run(StartBuildOrRespondWithBusy.java:46)
at org.gradle.launcher.daemon.server.DaemonStateCoordinator$1.run(DaemonStateCoordinator.java:246)
at org.gradle.internal.concurrent.DefaultExecutorFactory$StoppableExecutorImpl$1.run(DefaultExecutorFactory.java:64)
Caused by: org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':dex'.
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:69)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:46)
at org.gradle.api.internal.tasks.execution.PostExecutionAnalysisTaskExecuter.execute(PostExecutionAnalysisTaskExecuter.java:35)
at org.gradle.api.internal.tasks.execution.SkipUpToDateTaskExecuter.execute(SkipUpToDateTaskExecuter.java:64)
at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execute(ValidatingTaskExecuter.java:58)
at org.gradle.api.internal.tasks.execution.SkipEmptySourceFilesTaskExecuter.execute(SkipEmptySourceFilesTaskExecuter.java:42)
at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoActionsExecuter.java:52)
at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter.java:53)
at org.gradle.api.internal.tasks.execution.ExecuteAtMostOnceTaskExecuter.execute(ExecuteAtMostOnceTaskExecuter.java:43)
at org.gradle.api.internal.AbstractTask.executeWithoutThrowingTaskFailure(AbstractTask.java:305)
at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.executeTask(AbstractTaskPlanExecutor.java:79)
at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.processTask(AbstractTaskPlanExecutor.java:63)
at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.run(AbstractTaskPlanExecutor.java:51)
at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor.process(DefaultTaskPlanExecutor.java:23)
at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter.execute(DefaultTaskGraphExecuter.java:88)
at org.gradle.execution.SelectedTaskExecutionAction.execute(SelectedTaskExecutionAction.java:29)
at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:62)
at org.gradle.execution.DefaultBuildExecuter.access$200(DefaultBuildExecuter.java:23)
at org.gradle.execution.DefaultBuildExecuter$2.proceed(DefaultBuildExecuter.java:68)
at org.gradle.execution.DryRunBuildExecutionAction.execute(DryRunBuildExecutionAction.java:32)
at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:62)
at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:55)
at org.gradle.initialization.DefaultGradleLauncher.doBuildStages(DefaultGradleLauncher.java:149)
at org.gradle.initialization.DefaultGradleLauncher.doBuild(DefaultGradleLauncher.java:106)
... 32 more
Caused by: org.gradle.api.GradleException:
at org.javafxports.jfxmobile.plugin.android.task.Dex.dex(Dex.groovy:57)
at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:63)
at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.doExecute(AnnotationProcessingTaskFactory.java:218)
at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.execute(AnnotationProcessingTaskFactory.java:211)
at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.execute(AnnotationProcessingTaskFactory.java:200)
at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:579)
at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:562)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeAction(ExecuteActionsTaskExecuter.java:80)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:61)
... 55 more

help me please...

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':androidInstall'.
> com.android.builder.testing.api.DeviceException: java.lang.RuntimeException: No connected devices!

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':mergeClassesIntoJar'.
> Cannot expand ZIP 'C:\Tools\android\android-sdk_r24.3.3-windows\android-sdk-windows\extras\android\support\multidex\library\libs\android-support-multidex.jar' as it does not exist.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

e.g.

android {
androidSdk = 'C:/tools/android/android-sdk'
compileSdkVersion = 21
}

FAILURE: Build failed with an exception.

* What went wrong:
ANDROID_HOME not specified. Either set it as a gradle property, a system environment variable or directly in your build.gradle by setting the extension jfxmobile.android.androidSdk.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

BUILD FAILED