Why am I getting an error when I try to run my socket program in Java?

Question

I'm using jcreatorLE and JDK 1.6 to run my program. I don't know why I get an error when I try to run. Could somebody explain the reason to me?

This is the code for the Server:

import java.io.*;
import java.net.*;

class ServidorTCP {
   // variable to wait for connections
   private static ServerSocket servidor = null;
   // Variable to process client connections
   private static Socket conexion = null;
   // To send data to the client
   private static DataOutputStream salida = null;
   // Read the client
   private static DataInputStream entrada = null;

   public static void main(String args[]) {
      // args [0] is the port number to be listened to
      int puerto = new Integer(args[0]).intValue();

      // opening of the socket
      try {
         // Port where the client requests pending
         servidor = new ServerSocket(puerto);

         System.out.println("Servidor TCP iniciado...");
         boolean ejecutar = true;

         // It is starting to respond to requests
         while (ejecutar) {
            System.out.println("\nWaiting for Connections...");
            conexion = servidor.accept();      // Connection is expected

            // The connection was established with the client
            entrada = new DataInputStream(conexion.getInputStream());
            salida = new DataOutputStream(conexion.getOutputStream());

            System.out.println("\nConexion recibida...\n");
            String inicio = entrada.readUTF();
            System.out.println("Reception Date: "+new java.util.Date());
            System.out.println("From: "+(conexion.getInetAddress()).toString());
            System.out.println("received: "+inicio);

            salida.writeUTF(inicio.toUpperCase());
            entrada.close();
            salida.close();
            conexion.close();
         }

         // Close the socket
         System.out.println("\ntransmission completed...\n");
         servidor.close();
      } catch (Exception e) {
         e.printStackTrace();
      }
   }
}

This is the code for the client socket program:

import java.io.*;
import java.net.*;

class ClienteTCP {
   private static Socket           cliente = null;
   private static DataInputStream  entrada = null;
   private static DataOutputStream salida  = null;

   public static void main(String args[]) {
      int len = new Integer(args.length);
      String cadena = "";
      System.out.println("\nNumero de arg: "+len);
      for (int i=2; i<len;i++) {
         cadena = cadena + args[i];
         cadena = cadena + " ";
      }

      System.out.println("\nLa Cadena: "+cadena);
      int puerto = new Integer(args[1]).intValue();

      try {
         cliente = new Socket(args[0],puerto);
         entrada = new DataInputStream(cliente.getInputStream());
         salida = new DataOutputStream(cliente.getOutputStream());

         //SENDING INFORMATION DATA
         System.out.println("\nEnviando datos al servidor: "+cadena);
         salida.writeUTF(cadena);

         //Recibiendo la información
         System.out.println("Recibido: "+entrada.readUTF());
         entrada.close();
         salida.close();

         //Cierre del socket
         cliente.close();
         System.out.println("\nConexion terminada...\n");
      } catch (Exception e) {
         e.printStackTrace();
      }
   }
}

This is the result from running it:

[Loaded java.lang.Object from shared objects file]
[Loaded java.io.Serializable from shared objects file]
[Loaded java.lang.Comparable from shared objects file]
[Loaded java.lang.CharSequence from shared objects file]
[Loaded java.lang.String from shared objects file]
[Loaded java.lang.reflect.GenericDeclaration from shared objects file]
[Loaded java.lang.reflect.Type from shared objects file]
[Loaded java.lang.reflect.AnnotatedElement from shared objects file]
[Loaded java.lang.Class from shared objects file]
[Loaded java.lang.Cloneable from shared objects file]
[Loaded java.lang.ClassLoader from shared objects file]
[Loaded java.lang.System from shared objects file]
[Loaded java.lang.Throwable from shared objects file]
[Loaded java.lang.Error from shared objects file]
[Loaded java.lang.ThreadDeath from shared objects file]
[Loaded java.lang.Exception from shared objects file]
[Loaded java.lang.RuntimeException from shared objects file]
[Loaded java.security.ProtectionDomain from shared objects file]
[Loaded java.security.AccessControlContext from shared objects file]
[Loaded java.lang.ClassNotFoundException from shared objects file]
[Loaded java.lang.LinkageError from shared objects file]
[Loaded java.lang.NoClassDefFoundError from shared objects file]
[Loaded java.lang.ClassCastException from shared objects file]
[Loaded java.lang.ArrayStoreException from shared objects file]
[Loaded java.lang.VirtualMachineError from shared objects file]
[Loaded java.lang.OutOfMemoryError from shared objects file]
[Loaded java.lang.StackOverflowError from shared objects file]
[Loaded java.lang.IllegalMonitorStateException from shared objects file]
[Loaded java.lang.ref.Reference from shared objects file]
[Loaded java.lang.ref.SoftReference from shared objects file]
[Loaded java.lang.ref.WeakReference from shared objects file]
[Loaded java.lang.ref.FinalReference from shared objects file]
[Loaded java.lang.ref.PhantomReference from shared objects file]
[Loaded java.lang.ref.Finalizer from shared objects file]
[Loaded java.lang.Runnable from shared objects file]
[Loaded java.lang.Thread from shared objects file]
[Loaded java.lang.Thread$UncaughtExceptionHandler from shared objects file]
[Loaded java.lang.ThreadGroup from shared objects file]
[Loaded java.util.Dictionary from shared objects file]
[Loaded java.util.Map from shared objects file]
[Loaded java.util.Hashtable from shared objects file]
[Loaded java.util.Properties from shared objects file]
[Loaded java.lang.reflect.AccessibleObject from shared objects file]
[Loaded java.lang.reflect.Member from shared objects file]
[Loaded java.lang.reflect.Field from shared objects file]
[Loaded java.lang.reflect.Method from shared objects file]
[Loaded java.lang.reflect.Constructor from shared objects file]
[Loaded sun.reflect.MagicAccessorImpl from shared objects file]
[Loaded sun.reflect.MethodAccessor from shared objects file]
[Loaded sun.reflect.MethodAccessorImpl from shared objects file]
[Loaded sun.reflect.ConstructorAccessor from shared objects file]
[Loaded sun.reflect.ConstructorAccessorImpl from shared objects file]
[Loaded sun.reflect.DelegatingClassLoader from shared objects file]
[Loaded sun.reflect.ConstantPool from shared objects file]
[Loaded sun.reflect.FieldAccessor from shared objects file]
[Loaded sun.reflect.FieldAccessorImpl from shared objects file]
[Loaded sun.reflect.UnsafeFieldAccessorImpl from shared objects file]
[Loaded sun.reflect.UnsafeStaticFieldAccessorImpl from shared objects file]
[Loaded java.lang.Iterable from shared objects file]
[Loaded java.util.Collection from shared objects file]
[Loaded java.util.AbstractCollection from shared objects file]
[Loaded java.util.List from shared objects file]
[Loaded java.util.AbstractList from shared objects file]
[Loaded java.util.RandomAccess from shared objects file]
[Loaded java.util.Vector from shared objects file]
[Loaded java.lang.Appendable from shared objects file]
[Loaded java.lang.AbstractStringBuilder from shared objects file]
[Loaded java.lang.StringBuffer from shared objects file]
[Loaded java.lang.StackTraceElement from shared objects file]
[Loaded java.nio.Buffer from shared objects file]
[Loaded sun.misc.AtomicLong from shared objects file]
[Loaded sun.misc.AtomicLongCSImpl from shared objects file]
[Loaded java.lang.Boolean from shared objects file]
[Loaded java.lang.Character from shared objects file]
[Loaded java.lang.Number from shared objects file]
[Loaded java.lang.Float from shared objects file]
[Loaded java.lang.Double from shared objects file]
[Loaded java.lang.Byte from shared objects file]
[Loaded java.lang.Short from shared objects file]
[Loaded java.lang.Integer from shared objects file]
[Loaded java.lang.Long from shared objects file]
[Loaded java.io.ObjectStreamField from shared objects file]
[Loaded java.util.Comparator from shared objects file]
[Loaded java.lang.String$CaseInsensitiveComparator from shared objects file]
[Loaded java.security.Guard from shared objects file]
[Loaded java.security.Permission from shared objects file]
[Loaded java.security.BasicPermission from shared objects file]
[Loaded java.lang.RuntimePermission from shared objects file]
[Loaded java.util.AbstractMap from shared objects file]
[Loaded sun.misc.SoftCache from shared objects file]
[Loaded java.lang.ref.ReferenceQueue from shared objects file]
[Loaded java.lang.ref.ReferenceQueue$Null from shared objects file]
[Loaded java.lang.ref.ReferenceQueue$Lock from shared objects file]
[Loaded java.util.HashMap from shared objects file]
[Loaded java.lang.annotation.Annotation from shared objects file]
[Loaded java.util.Map$Entry from shared objects file]
[Loaded java.util.HashMap$Entry from shared objects file]
[Loaded java.security.AccessController from shared objects file]
[Loaded java.lang.reflect.ReflectPermission from shared objects file]
[Loaded java.security.PrivilegedAction from shared objects file]
[Loaded sun.reflect.ReflectionFactory$GetReflectionFactoryAction from shared objects file]
[Loaded java.util.Stack from shared objects file]
[Loaded sun.reflect.ReflectionFactory from shared objects file]
[Loaded java.lang.ref.Reference$Lock from shared objects file]
[Loaded java.lang.ref.Reference$ReferenceHandler from shared objects file]
[Loaded java.lang.ref.Finalizer$FinalizerThread from shared objects file]
[Loaded java.util.Enumeration from shared objects file]
[Loaded java.util.Hashtable$EmptyEnumerator from shared objects file]
[Loaded java.util.Iterator from shared objects file]
[Loaded java.util.Hashtable$EmptyIterator from shared objects file]
[Loaded java.util.Hashtable$Entry from shared objects file]
[Loaded sun.misc.Version from shared objects file]
[Loaded java.lang.Runtime from shared objects file]
[Loaded sun.reflect.Reflection from shared objects file]
[Loaded java.util.Collections from shared objects file]
[Loaded java.util.Set from shared objects file]
[Loaded java.util.AbstractSet from shared objects file]
[Loaded java.util.Collections$EmptySet from shared objects file]
[Loaded java.util.Collections$EmptyList from shared objects file]
[Loaded java.util.Collections$EmptyMap from shared objects file]
[Loaded java.util.Collections$ReverseComparator from shared objects file]
[Loaded java.util.Collections$SynchronizedMap from shared objects file]
[Loaded java.io.File from shared objects file]
[Loaded java.io.FileSystem from shared objects file]
[Loaded java.io.Win32FileSystem from shared objects file]
[Loaded java.io.WinNTFileSystem from shared objects file]
[Loaded java.io.ExpiringCache from shared objects file]
[Loaded java.util.LinkedHashMap from shared objects file]
[Loaded java.io.ExpiringCache$1 from shared objects file]
[Loaded java.util.LinkedHashMap$Entry from shared objects file]
[Loaded sun.security.action.GetPropertyAction from shared objects file]
[Loaded java.lang.StringBuilder from shared objects file]
[Loaded java.util.Arrays from shared objects file]
[Loaded java.lang.Math from shared objects file]
[Loaded sun.misc.JavaIODeleteOnExitAccess from shared objects file]
[Loaded java.io.File$1 from shared objects file]
[Loaded sun.misc.SharedSecrets from shared objects file]
[Loaded sun.misc.Unsafe from shared objects file]
[Loaded java.lang.IncompatibleClassChangeError from shared objects file]
[Loaded java.lang.NoSuchMethodError from shared objects file]
[Loaded sun.jkernel.DownloadManager from shared objects file]
[Loaded java.lang.ThreadLocal from shared objects file]
[Loaded sun.jkernel.DownloadManager$1 from shared objects file]
[Loaded java.util.concurrent.atomic.AtomicInteger from shared objects file]
[Loaded java.lang.Class$3 from shared objects file]
[Loaded java.lang.reflect.Modifier from shared objects file]
[Loaded sun.reflect.LangReflectAccess from shared objects file]
[Loaded java.lang.reflect.ReflectAccess from shared objects file]
[Loaded sun.jkernel.DownloadManager$2 from shared objects file]
[Loaded java.lang.ClassLoader$3 from shared objects file]
[Loaded java.io.ExpiringCache$Entry from shared objects file]
[Loaded java.lang.ClassLoader$NativeLibrary from shared objects file]
[Loaded java.io.Closeable from shared objects file]
[Loaded java.io.InputStream from shared objects file]
[Loaded java.io.FileInputStream from shared objects file]
[Loaded java.io.FileDescriptor from shared objects file]
[Loaded java.io.Flushable from shared objects file]
[Loaded java.io.OutputStream from shared objects file]
[Loaded java.io.FileOutputStream from shared objects file]
[Loaded java.io.FilterInputStream from shared objects file]
[Loaded java.io.BufferedInputStream from shared objects file]
[Loaded java.util.concurrent.atomic.AtomicReferenceFieldUpdater from shared objects file]
[Loaded java.util.concurrent.atomic.AtomicReferenceFieldUpdater$AtomicReferenceFieldUpdaterImpl from shared objects file]
[Loaded sun.reflect.misc.ReflectUtil from shared objects file]
[Loaded java.io.FilterOutputStream from shared objects file]
[Loaded java.io.PrintStream from shared objects file]
[Loaded java.io.BufferedOutputStream from shared objects file]
[Loaded java.io.Writer from shared objects file]
[Loaded java.io.OutputStreamWriter from shared objects file]
[Loaded sun.nio.cs.StreamEncoder from shared objects file]
[Loaded java.nio.charset.Charset from shared objects file]
[Loaded java.nio.charset.spi.CharsetProvider from shared objects file]
[Loaded sun.nio.cs.FastCharsetProvider from shared objects file]
[Loaded sun.nio.cs.StandardCharsets from shared objects file]
[Loaded sun.util.PreHashedMap from shared objects file]
[Loaded sun.nio.cs.StandardCharsets$Aliases from shared objects file]
[Loaded sun.nio.cs.StandardCharsets$Classes from shared objects file]
[Loaded sun.nio.cs.StandardCharsets$Cache from shared objects file]
[Loaded sun.nio.cs.HistoricallyNamedCharset from shared objects file]
[Loaded sun.nio.cs.MS1252 from shared objects file]
[Loaded java.lang.Class$1 from shared objects file]
[Loaded sun.reflect.ReflectionFactory$1 from shared objects file]
[Loaded sun.reflect.NativeConstructorAccessorImpl from shared objects file]
[Loaded sun.reflect.DelegatingConstructorAccessorImpl from shared objects file]
[Loaded sun.misc.VM from shared objects file]
[Loaded java.nio.charset.CharsetEncoder from shared objects file]
[Loaded sun.nio.cs.SingleByteEncoder from shared objects file]
[Loaded sun.nio.cs.MS1252$Encoder from shared objects file]
[Loaded java.nio.charset.CodingErrorAction from shared objects file]
[Loaded java.nio.charset.CharsetDecoder from shared objects file]
[Loaded sun.nio.cs.SingleByteDecoder from shared objects file]
[Loaded sun.nio.cs.MS1252$Decoder from shared objects file]
[Loaded java.nio.ByteBuffer from shared objects file]
[Loaded java.nio.HeapByteBuffer from shared objects file]
[Loaded java.nio.Bits from shared objects file]
[Loaded java.nio.ByteOrder from shared objects file]
[Loaded java.lang.Readable from shared objects file]
[Loaded java.nio.CharBuffer from shared objects file]
[Loaded java.nio.HeapCharBuffer from shared objects file]
[Loaded java.nio.charset.CoderResult from shared objects file]
[Loaded java.nio.charset.CoderResult$Cache from shared objects file]
[Loaded java.nio.charset.CoderResult$1 from shared objects file]
[Loaded java.nio.charset.CoderResult$2 from shared objects file]
[Loaded sun.nio.cs.Surrogate$Parser from shared objects file]
[Loaded sun.nio.cs.Surrogate from shared objects file]
[Loaded java.io.BufferedWriter from shared objects file]
[Loaded java.lang.Terminator from shared objects file]
[Loaded sun.misc.SignalHandler from shared objects file]
[Loaded java.lang.Terminator$1 from shared objects file]
[Loaded sun.misc.Signal from shared objects file]
[Loaded sun.misc.NativeSignalHandler from shared objects file]
[Loaded java.io.Console from shared objects file]
[Loaded sun.misc.JavaIOAccess from shared objects file]
[Loaded java.io.Console$1 from shared objects file]
[Loaded java.io.Console$1$1 from shared objects file]
[Loaded java.lang.Shutdown from shared objects file]
[Loaded java.util.ArrayList from shared objects file]
[Loaded java.lang.Shutdown$Lock from shared objects file]
[Loaded java.lang.ApplicationShutdownHooks from shared objects file]
[Loaded java.util.IdentityHashMap from shared objects file]
[Loaded sun.misc.OSEnvironment from shared objects file]
[Loaded sun.io.Win32ErrorMode from shared objects file]
[Loaded sun.misc.JavaLangAccess from shared objects file]
[Loaded java.lang.System$2 from shared objects file]
[Loaded java.lang.NullPointerException from shared objects file]
[Loaded java.lang.ArithmeticException from shared objects file]
[Loaded java.lang.Compiler from shared objects file]
[Loaded java.lang.Compiler$1 from shared objects file]
[Loaded sun.misc.Launcher from shared objects file]
[Loaded java.net.URLStreamHandlerFactory from shared objects file]
[Loaded sun.misc.Launcher$Factory from shared objects file]
[Loaded java.security.SecureClassLoader from shared objects file]
[Loaded java.net.URLClassLoader from shared objects file]
[Loaded sun.misc.Launcher$ExtClassLoader from shared objects file]
[Loaded sun.security.util.Debug from shared objects file]
[Loaded sun.misc.JavaNetAccess from shared objects file]
[Loaded java.net.URLClassLoader$7 from shared objects file]
[Loaded java.util.StringTokenizer from shared objects file]
[Loaded java.security.PrivilegedExceptionAction from shared objects file]
[Loaded sun.misc.Launcher$ExtClassLoader$1 from shared objects file]
[Loaded sun.misc.MetaIndex from shared objects file]
[Loaded java.io.Reader from shared objects file]
[Loaded java.io.BufferedReader from shared objects file]
[Loaded java.io.InputStreamReader from shared objects file]
[Loaded java.io.FileReader from shared objects file]
[Loaded sun.nio.cs.StreamDecoder from shared objects file]
[Loaded java.lang.reflect.Array from shared objects file]
[Loaded java.util.Locale from shared objects file]
[Loaded java.util.concurrent.ConcurrentMap from shared objects file]
[Loaded java.util.concurrent.ConcurrentHashMap from shared objects file]
[Loaded java.util.concurrent.locks.Lock from shared objects file]
[Loaded java.util.concurrent.locks.ReentrantLock from shared objects file]
[Loaded java.util.concurrent.ConcurrentHashMap$Segment from shared objects file]
[Loaded java.util.concurrent.locks.AbstractOwnableSynchronizer from shared objects file]
[Loaded java.util.concurrent.locks.AbstractQueuedSynchronizer from shared objects file]
[Loaded java.util.concurrent.locks.ReentrantLock$Sync from shared objects file]
[Loaded java.util.concurrent.locks.ReentrantLock$NonfairSync from shared objects file]
[Loaded java.util.concurrent.locks.AbstractQueuedSynchronizer$Node from shared objects file]
[Loaded java.util.concurrent.ConcurrentHashMap$HashEntry from shared objects file]
[Loaded java.lang.CharacterDataLatin1 from shared objects file]
[Loaded java.io.ObjectStreamClass from shared objects file]
[Loaded sun.net.www.ParseUtil from shared objects file]
[Loaded java.util.BitSet from shared objects file]
[Loaded java.net.URL from shared objects file]
[Loaded java.net.Parts from shared objects file]
[Loaded java.net.URLStreamHandler from shared objects file]
[Loaded sun.net.www.protocol.file.Handler from shared objects file]
[Loaded java.util.HashSet from shared objects file]
[Loaded sun.misc.URLClassPath from shared objects file]
[Loaded sun.net.www.protocol.jar.Handler from shared objects file]
[Loaded sun.misc.Launcher$AppClassLoader from shared objects file]
[Loaded sun.misc.Launcher$AppClassLoader$1 from shared objects file]
[Loaded java.lang.SystemClassLoaderAction from shared objects file]
[Loaded java.lang.StringCoding from shared objects file]
[Loaded java.lang.ThreadLocal$ThreadLocalMap from shared objects file]
[Loaded java.lang.ThreadLocal$ThreadLocalMap$Entry from shared objects file]
[Loaded java.lang.StringCoding$StringDecoder from shared objects file]
[Loaded java.net.URLClassLoader$1 from shared objects file]
[Loaded sun.misc.URLClassPath$3 from shared objects file]
[Loaded sun.misc.URLClassPath$Loader from shared objects file]
[Loaded sun.misc.URLClassPath$JarLoader from shared objects file]
[Loaded java.security.PrivilegedActionException from shared objects file]
[Loaded sun.misc.URLClassPath$FileLoader from shared objects file]
[Loaded sun.misc.Resource from shared objects file]
[Loaded sun.misc.URLClassPath$FileLoader$1 from shared objects file]
[Loaded sun.nio.ByteBuffered from shared objects file]
[Loaded java.security.CodeSource from shared objects file]
[Loaded java.security.PermissionCollection from shared objects file]
[Loaded java.security.Permissions from shared objects file]
[Loaded java.net.URLConnection from shared objects file]
[Loaded sun.net.www.URLConnection from shared objects file]
[Loaded sun.net.www.protocol.file.FileURLConnection from shared objects file]
[Loaded java.net.ContentHandler from shared objects file]
[Loaded java.net.UnknownContentHandler from shared objects file]
[Loaded sun.net.www.MessageHeader from shared objects file]
[Loaded java.io.FilePermission from shared objects file]
[Loaded java.io.FilePermission$1 from shared objects file]
[Loaded java.security.Policy from shared objects file]
[Loaded sun.security.provider.PolicyFile from shared objects file]
[Loaded java.security.Policy$UnsupportedEmptyCollection from shared objects file]
[Loaded java.io.FilePermissionCollection from shared objects file]
[Loaded java.security.AllPermission from shared objects file]
[Loaded java.security.UnresolvedPermission from shared objects file]
[Loaded java.security.BasicPermissionCollection from shared objects file]
[Loaded java.security.Principal from shared objects file]
[Loaded java.security.cert.Certificate from shared objects file]
[Loaded ServidorTCP from file:/C:/Users/administrador/Documents/]
[Loaded java.lang.IndexOutOfBoundsException from shared objects file]
[Loaded java.lang.ArrayIndexOutOfBoundsException from shared objects file]

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0
    at ServidorTCP.main(ServidorTCP.java:21)

[Loaded java.util.AbstractList$Itr from shared objects file]
[Loaded java.util.IdentityHashMap$KeySet from shared objects file]
[Loaded java.util.IdentityHashMap$IdentityHashMapIterator from shared objects file]
[Loaded java.util.IdentityHashMap$KeyIterator from shared objects file]
[Loaded java.io.DeleteOnExitHook from shared objects file]
[Loaded java.util.LinkedHashSet from shared objects file]
[Loaded java.util.HashMap$KeySet from shared objects file]
[Loaded java.util.LinkedHashMap$LinkedHashIterator from shared objects file]
[Loaded java.util.LinkedHashMap$KeyIterator from shared objects file]

Process completed.

Answer 1

You have to specify the port number at the command line.

It is always useful to know how to read the logs.

See. In your logs you have a bunch of class names, but there is only one related to your code:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0
    at ServidorTCP.main(ServidorTCP.java:21)

The rest of them are all about java.lang, java.util, java.io, etc, classes that you didn't coded.

If you look at that error line it says:

 java.lang.ArrayIndexOutOfBoundsException:

That means that you attempted to access an array out of its bounds . That is if the array size is 5 you probably attempted to access the 6th element. That's illegal, that's an exception ( more formally a RuntimeException that means you have a programming mistake )

Then the log adds information where that happened.

    at ServidorTCP.main(ServidorTCP.java:21)

In the class ServidorTCP ( in java file ServidorTCP at line 21.

You can take a look at that file at that line this is what it shows:

 20:    // args [0] is the port number to be heard
 21:    int puerto = new Integer(args[0]).intValue();

That says, the value of the variable "puerto" will be a new Integer created with the content of args[0] That is the first element of the args array.

That array is defined in the main method:

   public static void main(String args[]){

And filled automatically with the command line arguments.

So, if you ran your program without providing an argument the search of index 0 in the array args will fail.

I don't know exactly where in jcreator you can add command line arguments, but I'm pretty sure somewhere in a "Run" menu, or in the "Run" configuration or something like that, there should be something like "program arguments" You can fill that value with a port number, try using 8085.

OR

You can also change the line 21 of the server and initialize it like this:

//int puerto = new Integer(args[0]).intValue();
int puerto = 8085; // por mis pistolas :) 

And see it run.

Answer 2

Sounds like when you're starting the server you're not giving it any command-line arguments. In other words, you're running something like:

java -cp . ServidorTCP

when you should be running

java -cp . ServidorTCP 40000

(to start the server on port 40000)

If you're starting the program from the IDE, you need to find out how to pass in arguments when it starts the program.

Answer 3

Since its an ArrayIndexOutOfBounds exception, I would start looking at where you are using arrays. So, in your case, its where you are trying to grab the port number from the array of arguments. So take a look at that first, and make sure you are passing a port number in as a command line argument.

Answer 4

Look the signature of your main() method:

public static void main(String args[])

The error is here:

int puerto = new Integer(args[0]).intValue();

If you invoke your program by passing no arguments, it'll try to read an integer from an array that is in fact empty.

If you doesn't want to care about parameters, just do this:

int arguments = new Integer (args.length);

if (arguments = 0) {
  this.puerto = 4000;
}

That should do the job. If no arguments are passed, it'll just assume port 4000 (or whatever port you choose) as the default port.