Develop Reference

newly installed android studio not opening

I'm getting the following error when I launch the android studio
my android studio version is android-studio-2020.3.1.25
I have tried uninstalling the and re-installing and have also tried to delete local and roaming files too.
I'm also not finding any solution on the site
java.util.concurrent.CompletionException: java.lang.IllegalStateException: failed to create a child event loop
at java.base/java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:314)
at java.base/java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:319)
at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1702)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.util.concurrent.Executors$PrivilegedThreadFactory$1$1.run(Executors.java:668)
at java.base/java.util.concurrent.Executors$PrivilegedThreadFactory$1$1.run(Executors.java:665)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.base/java.util.concurrent.Executors$PrivilegedThreadFactory$1.run(Executors.java:665)
at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.IllegalStateException: failed to create a child event loop
at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:88)
at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:58)
at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:47)
at io.netty.channel.MultithreadEventLoopGroup.<init>(MultithreadEventLoopGroup.java:59)
at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:86)
at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:81)
at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:68)
at org.jetbrains.io.BuiltInServerKt.multiThreadEventLoopGroup(BuiltInServer.kt:144)
at org.jetbrains.io.BuiltInServerKt.access$multiThreadEventLoopGroup(BuiltInServer.kt:1)
at org.jetbrains.io.BuiltInServer$Companion.start(BuiltInServer.kt:54)
at org.jetbrains.io.BuiltInServer.start(BuiltInServer.kt)
at com.intellij.idea.SocketLock.lambda$lockAndTryActivate$2(SocketLock.java:171)
at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1700)
... 7 more
Caused by: io.netty.channel.ChannelException: failed to open a new selector
at io.netty.channel.nio.NioEventLoop.openSelector(NioEventLoop.java:175)
at io.netty.channel.nio.NioEventLoop.<init>(NioEventLoop.java:142)
at io.netty.channel.nio.NioEventLoopGroup.newChild(NioEventLoopGroup.java:146)
at io.netty.channel.nio.NioEventLoopGroup.newChild(NioEventLoopGroup.java:37)
at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:84)
... 19 more
Caused by: java.io.IOException: Unable to establish loopback connection
at java.base/sun.nio.ch.PipeImpl$Initializer.run(PipeImpl.java:94)
at java.base/sun.nio.ch.PipeImpl$Initializer.run(PipeImpl.java:61)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.base/sun.nio.ch.PipeImpl.<init>(PipeImpl.java:171)
at java.base/sun.nio.ch.SelectorProviderImpl.openPipe(SelectorProviderImpl.java:50)
at java.base/java.nio.channels.Pipe.open(Pipe.java:155)
at java.base/sun.nio.ch.WindowsSelectorImpl.<init>(WindowsSelectorImpl.java:142)
at java.base/sun.nio.ch.WindowsSelectorProvider.openSelector(WindowsSelectorProvider.java:44)
at io.netty.channel.nio.NioEventLoop.openSelector(NioEventLoop.java:173)
... 23 more
Caused by: java.net.BindException: Cannot assign requested address: connect
at java.base/sun.nio.ch.Net.connect0(Native Method)
at java.base/sun.nio.ch.Net.connect(Net.java:476)
at java.base/sun.nio.ch.Net.connect(Net.java:468)
at java.base/sun.nio.ch.SocketChannelImpl.connect(SocketChannelImpl.java:694)
at java.base/java.nio.channels.SocketChannel.open(SocketChannel.java:194)
at java.base/sun.nio.ch.PipeImpl$Initializer$LoopbackConnector.run(PipeImpl.java:127)
at java.base/sun.nio.ch.PipeImpl$Initializer.run(PipeImpl.java:76)
... 31 more
-----
Your JRE: 11.0.10+0-b96-7249189 amd64 (Oracle Corporation)
C:\Program Files\Android\Android Studio\jre

The log shows that there is a problem with establishing loopback connection . please check your firewall / network connections (e.g. VPN etc).

Connection refused between Azure monitor and Application-insights java agent

Attempting to add Application-insights to a java application running in AKS.
Followed the steps provided here: https://learn.microsoft.com/en-us/azure/azure-monitor/app/java-in-process-agent
an ai-agent.jar is placed in the root of the image.
The connection string is provided via environment variables.
the image is initialized with the following commands:
command: ["java"]
args: ["-javaagent:/agent.jar", "-jar", "/app.jar"]
both the spring-boot app and the agent do start, but the logs for the agent are followed up by these errors:
2021-08-19 15:43:26.914Z WARN c.m.a.a.i.q.QuickPulsePingSender - Live metrics endpoint ping failed io.netty.channel.AbstractChannel$AnnotatedConnectException: finishConnect(..) failed: Connection refused: rt.services.visualstudio.com/157.55.177.6:443 (future failures will be aggregated and logged once every 5 minutes)
reactor.core.Exceptions$ReactiveException: io.netty.channel.AbstractChannel$AnnotatedConnectException: finishConnect(..) failed: Connection refused: rt.services.visualstudio.com/157.55.177.6:443
at reactor.core.Exceptions.propagate(Exceptions.java:392)
at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:97)
at reactor.core.publisher.Mono.block(Mono.java:1703)
at com.microsoft.applicationinsights.agent.internal.quickpulse.QuickPulsePingSender.ping(QuickPulsePingSender.java:95)
at com.microsoft.applicationinsights.agent.internal.quickpulse.QuickPulseCoordinator.ping(QuickPulseCoordinator.java:106)
at com.microsoft.applicationinsights.agent.internal.quickpulse.QuickPulseCoordinator.run(QuickPulseCoordinator.java:63)
at java.base/java.lang.Thread.run(Thread.java:829)
Suppressed: java.lang.Exception: #block terminated with an error
at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:99)
... 5 common frames omitted
Caused by: io.netty.channel.AbstractChannel$AnnotatedConnectException: finishConnect(..) failed: Connection refused: rt.services.visualstudio.com/157.55.177.6:443
Caused by: java.net.ConnectException: finishConnect(..) failed: Connection refused
at io.netty.channel.unix.Errors.newConnectException0(Errors.java:155)
at io.netty.channel.unix.Errors.handleConnectErrno(Errors.java:128)
at io.netty.channel.unix.Socket.finishConnect(Socket.java:278)
at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe.doFinishConnect(AbstractEpollChannel.java:710)
at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe.finishConnect(AbstractEpollChannel.java:687)
at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe.epollOutReady(AbstractEpollChannel.java:567)
at io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:470)
at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:378)
at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.base/java.lang.Thread.run(Thread.java:829)
2021-08-19 15:43:27.888Z INFO c.m.applicationinsights.agent - ApplicationInsights Java Agent 3.2.0-BETA.2 started successfully (PID 1)
2021-08-19 15:43:27.893Z WARN c.m.a.a.i.i.AppIdSupplier$GetAppIdTask - unable to retrieve appId exception sending request to https://westeurope-3.in.applicationinsights.azure.com/api/profiles/<INSTRUMENTATION_KEY>/appId (future failures will be aggregated and logged once every 5 minutes)
reactor.core.Exceptions$ReactiveException: io.netty.channel.AbstractChannel$AnnotatedConnectException: finishConnect(..) failed: Connection refused: westeurope-3.in.applicationinsights.azure.com/13.69.65.23:443
at reactor.core.Exceptions.propagate(Exceptions.java:392)
at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:97)
at reactor.core.publisher.Mono.block(Mono.java:1703)
at com.microsoft.applicationinsights.agent.internal.init.AppIdSupplier$GetAppIdTask.run(AppIdSupplier.java:123)
at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.lang.Thread.run(Thread.java:829)
Suppressed: java.lang.Exception: #block terminated with an error
at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:99)
... 8 common frames omitted
Caused by: io.netty.channel.AbstractChannel$AnnotatedConnectException: finishConnect(..) failed: Connection refused: westeurope-3.in.applicationinsights.azure.com/13.69.65.23:443
Caused by: java.net.ConnectException: finishConnect(..) failed: Connection refused
at io.netty.channel.unix.Errors.newConnectException0(Errors.java:155)
at io.netty.channel.unix.Errors.handleConnectErrno(Errors.java:128)
at io.netty.channel.unix.Socket.finishConnect(Socket.java:278)
at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe.doFinishConnect(AbstractEpollChannel.java:710)
at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe.finishConnect(AbstractEpollChannel.java:687)
at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe.epollOutReady(AbstractEpollChannel.java:567)
at io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:470)
at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:378)
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.base/java.lang.Thread.run(Thread.java:829)
as far as I can tell, the issue seems to stem from the agent not being able to retrieve the appId, but sshing into the container and performing a curl
curl https://westeurope-3.in.applicationinsights.azure.com/api/profiles/<INSTRUMENTATION_KEY>/appId
does return a result, leading me to believe that the pod does have a connection to the Azure monitor instance.
I've tried multiple versions of the agent jar, tried the SDK and custom events inside the spring-boot app, manually starting a secondary java instance, provided the connection string/instrumentation-key using kubectl, local env variable, applicationinsights.json file, and as a JVM parameter, all this to no avail.
right now it feels like I'm all out of ideas and unable to get any further with this issue without some external input.
Does anyone recognize this issue, or tackled something similar before?

I've faced similar situation and it seems that in my case, the Java app was running inside a VM without outbound access to the internet. This way,it wasn't reaching Azure Monitor/App Insight DNS and not sending the data to the ingestion service.
Have you tried running a CURL within your app infrastructure and making sure it can outbound http traffic?

Tomcat 9.0.16 : Failed to initialize component [Connector[HTTP/1.1-8080]]

Recently I have downloaded JDK 11.0.2 & Tomcat 9.0.16 and set the environment variables, but whenever I am starting the tomcat it is showing the following exception in the console and http://localhost:8080/ is not accessible.
Please help.
06-Mar-2019 03:34:43.186 SEVERE [main] org.apache.catalina.util.LifecycleBase.handleSubClassException Failed to initialize component [Connector[HTTP/1.1-8080]] org.apache.catalina.LifecycleException: Protocol handler initialization failed
at org.apache.catalina.connector.Connector.initInternal(Connector.java:983)
at org.apache.catalina.util.LifecycleBase.init(LifecycleBase.java:136)
at org.apache.catalina.core.StandardService.initInternal(StandardService.java:535)
at org.apache.catalina.util.LifecycleBase.init(LifecycleBase.java:136)
at org.apache.catalina.core.StandardServer.initInternal(StandardServer.java:1055)
at org.apache.catalina.util.LifecycleBase.init(LifecycleBase.java:136)
at org.apache.catalina.startup.Catalina.load(Catalina.java:589)
at org.apache.catalina.startup.Catalina.load(Catalina.java:612)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.apache.catalina.startup.Bootstrap.load(Bootstrap.java:306)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:491)
Caused by: java.io.IOException: Unable to establish loopback connection
at java.base/sun.nio.ch.PipeImpl$Initializer.run(PipeImpl.java:94)
at java.base/sun.nio.ch.PipeImpl$Initializer.run(PipeImpl.java:61)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.base/sun.nio.ch.PipeImpl.<init>(PipeImpl.java:171)
at java.base/sun.nio.ch.SelectorProviderImpl.openPipe(SelectorProviderImpl.java:50)
at java.base/java.nio.channels.Pipe.open(Pipe.java:155)
at java.base/sun.nio.ch.WindowsSelectorImpl.<init>(WindowsSelectorImpl.java:127)
at java.base/sun.nio.ch.WindowsSelectorProvider.openSelector(WindowsSelectorProvider.java:44)
at java.base/java.nio.channels.Selector.open(Selector.java:295)
at org.apache.tomcat.util.net.NioSelectorPool.getSharedSelector(NioSelectorPool.java:54)
at org.apache.tomcat.util.net.NioSelectorPool.close(NioSelectorPool.java:109)
at org.apache.tomcat.util.net.NioEndpoint.unbind(NioEndpoint.java:338)
at org.apache.tomcat.util.net.AbstractEndpoint.bindWithCleanup(AbstractEndpoint.java:1090)
at org.apache.tomcat.util.net.AbstractEndpoint.init(AbstractEndpoint.java:1098)
at org.apache.coyote.AbstractProtocol.init(AbstractProtocol.java:557)
at org.apache.coyote.http11.AbstractHttp11Protocol.init(AbstractHttp11Protocol.java:74)
at org.apache.catalina.connector.Connector.initInternal(Connector.java:980)
... 13 more
Caused by: java.net.ConnectException: Connection timed out: connect
at java.base/sun.nio.ch.Net.connect0(Native Method)
at java.base/sun.nio.ch.Net.connect(Net.java:482)
at java.base/sun.nio.ch.Net.connect(Net.java:474)
at java.base/sun.nio.ch.SocketChannelImpl.connect(SocketChannelImpl.java:694)
at java.base/java.nio.channels.SocketChannel.open(SocketChannel.java:194)
at java.base/sun.nio.ch.PipeImpl$Initializer$LoopbackConnector.run(PipeImpl.java:127)
at java.base/sun.nio.ch.PipeImpl$Initializer.run(PipeImpl.java:76)
... 29 more
I also tried with different connector ports but did not worked, but when i tried same thing with same configuration in another machine it worked without exception and localhost was accessible. Is there any problem with my machine.

This mistake means that your port is busy.
Stop Tomcat
Change the port number
Restart your app
Read more about the mistake here

Cannot start internal HTTP server... IntelliJ stopped working

I have IntelliJ and other development tools stopped working today.
IntelliJ says on start:
Cannot start internal HTTP server. Git integration, JavaScript
debugger and LiveEdit may operate with errors. Please check your
firewall settings and restart IntelliJ IDEA
Before this happened I was receiving strange errors on loopback connection on build which is now gone. Currently it says
Error:failed to create a child event loop
Gradle build says:
Protocol family unavaliable
Disabling firewall does not help.
UPDATE
IntelliJ log is full of messages like this:
Caused by: java.rmi.RemoteException: Cannot start maven service; nested exception is:
java.rmi.ConnectIOException: Exception creating connection to: localhost; nested exception is:
java.net.SocketException: Permission denied: connect
at org.jetbrains.idea.maven.server.MavenServerManager.create(MavenServerManager.java:165)
at org.jetbrains.idea.maven.server.MavenServerManager.create(MavenServerManager.java:71)
at org.jetbrains.idea.maven.server.RemoteObjectWrapper.getOrCreateWrappee(RemoteObjectWrapper.java:41)
at org.jetbrains.idea.maven.server.MavenServerManager$5.create(MavenServerManager.java:494)
at org.jetbrains.idea.maven.server.MavenServerManager$5.create(MavenServerManager.java:490)
at org.jetbrains.idea.maven.server.RemoteObjectWrapper.getOrCreateWrappee(RemoteObjectWrapper.java:41)
at org.jetbrains.idea.maven.server.MavenIndexerWrapper.getRemoteId(MavenIndexerWrapper.java:169)
at org.jetbrains.idea.maven.server.MavenIndexerWrapper.access$100(MavenIndexerWrapper.java:37)
at org.jetbrains.idea.maven.server.MavenIndexerWrapper$1.execute(MavenIndexerWrapper.java:64)
at org.jetbrains.idea.maven.server.RemoteObjectWrapper.perform(RemoteObjectWrapper.java:105)
... 39 more
Caused by: java.rmi.ConnectIOException: Exception creating connection to: localhost; nested exception is:
java.net.SocketException: Permission denied: connect
at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:631)
at sun.rmi.transport.tcp.TCPChannel.createConnection(TCPChannel.java:216)
at sun.rmi.transport.tcp.TCPChannel.newConnection(TCPChannel.java:202)
at sun.rmi.server.UnicastRef.newCall(UnicastRef.java:342)
at sun.rmi.registry.RegistryImpl_Stub.lookup(Unknown Source)
at com.intellij.execution.rmi.RemoteProcessSupport$3.compute(RemoteProcessSupport.java:256)
at com.intellij.execution.rmi.RemoteUtil.executeWithClassLoader(RemoteUtil.java:181)
at com.intellij.execution.rmi.RemoteProcessSupport.a(RemoteProcessSupport.java:252)
at com.intellij.execution.rmi.RemoteProcessSupport.acquire(RemoteProcessSupport.java:164)
at org.jetbrains.idea.maven.server.MavenServerManager.create(MavenServerManager.java:162)
... 48 more
Caused by: java.net.SocketException: Permission denied: connect
at java.net.TwoStacksPlainSocketImpl.socketConnect(Native Method)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:345)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:589)
at java.net.Socket.connect(Socket.java:538)
at java.net.Socket.<init>(Socket.java:434)
at java.net.Socket.<init>(Socket.java:211)
at sun.rmi.transport.proxy.RMIDirectSocketFactory.createSocket(RMIDirectSocketFactory.java:40)
at sun.rmi.transport.proxy.RMIMasterSocketFactory.createSocket(RMIMasterSocketFactory.java:148)
at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:613)
... 57 more
UPDATE 2
I found the root of the problem: this was caused by proxy autoconfiguration. By some reason address of 127.0.0.1 was processing by proxy and was leading to the web page of proxy server. The addition of
function FindProxyForURL(url,host)
{
if( host == '127.0.0.1' ) {
return "DIRECT";
}
to wpad.dat helped but I still don't understand an entire effect. I have proxy for a long time and it was no causing such an effect previously.
So I think this is also somehow related with IPv6 or something.

SimpleDB setup java.rmi.NotBoundException:simpledb

I want to install SimpleDB to my computer.I have already defined the CLASSPATH environment variable as
.;C:\SimpleDB
in user variables and the system variables CLASSPATH as
C:\Program Files\Java\jdk1.7.0_45\bin;C:\Program Files\Java\jdk1.7.0_45\jre\bin
and PATH as the same with CLASSPATH.I have opened command prompt and entered SimpleDB.Then I typed start rmiregistry.Another window is opened.After that I typed java simpledb.server.Startup studentdb.
The output is:
new transaction: 1
recovering existing database
transaction 1 committed
database server ready
After that I went to SimpleDB\studentClient\simpledb and type java CreateStudentDB.And it gave me the following error.
C:\SimpleDB\studentClient\simpledb>java CreateStudentDB
java.sql.SQLException: java.rmi.ConnectException: Connection refused to host: 10
.39.121.3; nested exception is:
java.net.ConnectException: Connection refused: connect
at simpledb.remote.SimpleDriver.connect(SimpleDriver.java:35)
at CreateStudentDB.main(CreateStudentDB.java:9)
Caused by: java.rmi.ConnectException: Connection refused to host: 10.39.121.3; n
ested exception is:
java.net.ConnectException: Connection refused: connect
at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:619)
at sun.rmi.transport.tcp.TCPChannel.createConnection(TCPChannel.java:216
)
at sun.rmi.transport.tcp.TCPChannel.newConnection(TCPChannel.java:202)
at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:129)
at java.rmi.server.RemoteObjectInvocationHandler.invokeRemoteMethod(Remo
teObjectInvocationHandler.java:194)
at java.rmi.server.RemoteObjectInvocationHandler.invoke(RemoteObjectInvo
cationHandler.java:148)
at com.sun.proxy.$Proxy0.connect(Unknown Source)
at simpledb.remote.SimpleDriver.connect(SimpleDriver.java:31)
... 1 more
Caused by: java.net.ConnectException: Connection refused: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketI
mpl.java:79)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.ja
va:339)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocket
Impl.java:200)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java
:182)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:579)
at java.net.Socket.connect(Socket.java:528)
at java.net.Socket.<init>(Socket.java:425)
at java.net.Socket.<init>(Socket.java:208)
at sun.rmi.transport.proxy.RMIDirectSocketFactory.createSocket(RMIDirect
SocketFactory.java:40)
at sun.rmi.transport.proxy.RMIMasterSocketFactory.createSocket(RMIMaster
SocketFactory.java:147)
at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:613)
... 8 more
rmiregistry window is already open, i didn't close it.Why does it give me such an error?
Please give an idea.
Thank you.

I just typed "java simpledb.server.Startup studentdb" to "start java simpledb.server.Startup studentdb", when creating database.Another window was opened.Then I continued the same operations in the previous window.It worked for me.