2 Questions

[AliBail]

Question 1.

How do you communicate over the internet using java, eg. Client - Server design. (as in VB you would probably use Winsock Control, but as Java is platform independant is their a class libarary or something that does it?)

Question 2.

Taking the Swing Message Box object / class, how do you create similar things to it, as I need to create a custom GUI for a program ive to do for uni.

And more importantly, is it more than likley beyond my abilities.

Thanks in advance

[plenderj]

Here's an example from a program I had to write last year in college.
This will listen for a conneciton, or make a connection and send a file through.

You should be able to pick bits and pieces out of this.
Make sure to import java.net.* and java.io.*;

	private static void connect ( String strHost , int port ) {
		Socket sock          = null;
		PrintWriter out      = null;
		BufferedReader bRead = null;
		String input         = "";
		long sentSoFar       = 0; 
		long prevSentSoFar   = 0;
		long lenOfFile       = 0; 
		int percentDone      = 0;       
		int lastPercentSent  = 0;
		int numSoFar         = 0;
		boolean isFirstLine  = true;
        
		try {				
			p("***************************************");
			p("*** Connecting ...                  ***");
			p("***************************************");			
			sock = new Socket( strHost , port );			
			p("***************************************");
			p("*** Connected                       ***");
			p("*** Now sending file ...            ***");
			p("***************************************");			
			out = new PrintWriter( sock.getOutputStream(), true );
			out.println( "filename : testPacket.txt" );			
			lenOfFile = (new File( "packet.txt" )).length();
			bRead = new BufferedReader( new FileReader( "packet.txt" ) );			
			while ( ( input = bRead.readLine() ) != null ) {
				sentSoFar = sentSoFar + (long)input.length();
				percentDone = (int)Math.round(((double)sentSoFar) / ((double)lenOfFile) * 100.0);
				if ( ! (percentDone == lastPercentSent) ) {
				    lastPercentSent = percentDone;
				    System.out.print(lastPercentSent + "% ");
				    numSoFar++;
				    if ( isFirstLine ) {
		                        if ( numSoFar == 12 ) {
		                            p();
		                            numSoFar = 0;
		                            isFirstLine = false;                        
		                        }
				    } else {
				        if ( numSoFar == 10 ) {
				            p();
				            numSoFar = 0;
				        }
				    }
				}				
				out.println( input );
			}
			p();
			p("***************************************");
			p("*** File has been sent !            ***");
			p("***************************************");			
			out.println( "*EOF*" ); out.close();
			main ( new String[0] );
		}			
		catch ( FileNotFoundException e ) {				
		    p("***************************************");
			p("*** Could not find file !           ***");
			p("***************************************");			
			doLoop();
		}
		catch ( UnknownHostException e ) { p( "Unknown host !" ); doLoop();	}
		catch ( IOException e ) {  }
	}
	
	
	private static void listen ( int port ) { 
        listen( port, false );
	}
	
	private static void listen ( int port , boolean showMessage ) {
	    ServerSocket serverSock = null;   
		Socket clientSock       = null;
		FileWriter out          = null;
		BufferedReader in       = null;
		String inputLine        = null;
		boolean receivedName    = false;
		boolean amFinished      = false;       
		if ( showMessage ) {
	        p("***************************************");
		    p("*** Listening ...                   ***");
		    p("***************************************");					
		}
		try {		
			serverSock = new ServerSocket( port ); 
			clientSock = serverSock.accept(); 
			in = new BufferedReader( new InputStreamReader( clientSock.getInputStream() ) );		
			while ( ( ( ( inputLine = in.readLine() ) != null ) && ( ! ( amFinished ) ) ) ) {	
				if ( ! ( receivedName ) ) {
					if ( inputLine.startsWith ( "filename : " ) ) {
					    out = new FileWriter( new File( inputLine.substring( 11 ) ) );
						receivedName = true;
					}
				} else {
					amFinished = inputLine.equals("*EOF*");
					if ( ! ( amFinished ) ) {
						if ( inputLine.equals("*die*") ) { 
							p("Received die command !"); out.close(); in.close();
							clientSock.close(); serverSock.close();	System.exit ( 0 );
						} else { 
			                out.write( inputLine + '\r' + '\n' );
						}
					}
				}
			}
			System.out.println("File received");
		    out.close(); in.close();
			clientSock.close(); serverSock.close();                        				
			listen( port );
		}
	    catch (IOException e) { p("Received Error :"); p(e.getMessage()); doLoop(); }								
	    p("***************************************");
	    p("*** Received File                   ***");
	    p("***************************************");
	}

[CornedBee]

Custom GUI? In Java?

Try writing a LookAndFeel class instead, it will make your swing app look different without any code changes (except loading the look and feel).