Deeplearning4j UI server failed to start.

gistfile1.txt

java.lang.reflect.InvocationTargetException
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:382)
	at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:321)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:873)
Caused by: org.deeplearning4j.exception.DL4JException: Deeplearning4j UI server failed to start.
	at org.deeplearning4j.ui.VertxUIServer.deploy(VertxUIServer.java:169)
	at org.deeplearning4j.ui.VertxUIServer.getInstance(VertxUIServer.java:130)
	at org.deeplearning4j.ui.VertxUIServer.getInstance(VertxUIServer.java:95)
	at org.deeplearning4j.ui.api.UIServer.getInstance(UIServer.java:70)
	at org.deeplearning4j.ui.api.UIServer.getInstance(UIServer.java:50)
	at ai.certifai.solution.convolution.mnist.MnistClassifier.main(MnistClassifier.java:137)
	... 11 more
Caused by: java.lang.RuntimeException: java.lang.RuntimeException: Deeplearning4j UI server failed to listen on port 9000
	at org.deeplearning4j.ui.VertxUIServer.lambda$null$6(VertxUIServer.java:185)
	at io.vertx.core.Future.future(Future.java:41)
	at org.deeplearning4j.ui.VertxUIServer.lambda$deploy$7(VertxUIServer.java:185)
	at io.vertx.core.Future.lambda$compose$3(Future.java:372)
	at io.vertx.core.impl.FutureImpl.tryFail(FutureImpl.java:195)
	at io.vertx.core.impl.FutureImpl.fail(FutureImpl.java:125)
	at io.vertx.core.impl.FutureImpl.handle(FutureImpl.java:178)
	at io.vertx.core.impl.FutureImpl.handle(FutureImpl.java:21)
	at io.vertx.core.impl.DeploymentManager.lambda$reportResult$6(DeploymentManager.java:518)
	at io.vertx.core.impl.ContextImpl.executeTask(ContextImpl.java:369)
	at io.vertx.core.impl.EventLoopContext.lambda$executeAsync$0(EventLoopContext.java:38)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:500)
	at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
	at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.RuntimeException: Deeplearning4j UI server failed to listen on port 9000
	at org.deeplearning4j.ui.VertxUIServer.lambda$start$16(VertxUIServer.java:385)
	at io.vertx.core.http.impl.HttpServerImpl.lambda$null$5(HttpServerImpl.java:299)
	... 9 more
Caused by: java.net.BindException: Address already in use
	at sun.nio.ch.Net.bind0(Native Method)
	at sun.nio.ch.Net.bind(Net.java:461)
	at sun.nio.ch.Net.bind(Net.java:453)
	at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:222)
	at io.netty.channel.socket.nio.NioServerSocketChannel.doBind(NioServerSocketChannel.java:134)
	at io.netty.channel.AbstractChannel$AbstractUnsafe.bind(AbstractChannel.java:550)
	at io.netty.channel.DefaultChannelPipeline$HeadContext.bind(DefaultChannelPipeline.java:1334)
	at io.netty.channel.AbstractChannelHandlerContext.invokeBind(AbstractChannelHandlerContext.java:506)
	at io.netty.channel.AbstractChannelHandlerContext.bind(AbstractChannelHandlerContext.java:491)
	at io.netty.channel.DefaultChannelPipeline.bind(DefaultChannelPipeline.java:973)
	at io.netty.channel.AbstractChannel.bind(AbstractChannel.java:248)
	at io.netty.bootstrap.AbstractBootstrap$2.run(AbstractBootstrap.java:356)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasksFrom(SingleThreadEventExecutor.java:428)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:377)
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:488)
	... 4 more
Exception running application ai.certifai.solution.convolution.mnist.MnistClassifier