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Ralf Coby

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since Jan 04, 2018
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Recent posts by Ralf Coby

I just forgot to push the "build"-button.
1 week ago
Hi community,

I've declared the dependencies below:

And this is my Websocket-Class:

But there is an error with my IDE.
I only can search in my IDE for the dependencies which depends to the annotations.
But my IDE doesnt get import-references.

So, i tried to import the library manually.

But it's not working.

I hope you can help me.

Thank you in advance
1 week ago
So, whatever. Can't help.

I have copied exactly the same sourcecode to a new java-project, and now it runs.


God moves in mysterious ways. Or something like that.
2 weeks ago

The problem occured even with a single GUI.

I am at my wits end
2 weeks ago
Hi community!

I have several Guis which all depends on a main-gui.
If i choose "Clean and Build" in my Netbeans-IDE, and i try to execute the .jar-file, then nothing happens.

I guss, its because of the several guis.

My gui-code is like this:

second Gui:

Third Gui:

Thank you in advance
2 weeks ago

The problem occured because my 2 JFrames had the same identifier.
2 weeks ago
Additional to the last post:
I have figured out, that the NullPointer probably depends on my second window,

I have to Winodws with a menubar.
If i invoke the getters and setter-method with my first window, then everything is fine.
But if I invoke my getters and setters with my second window, which opens if I choose a subject in the menubar, then i get the NullPointer.
So I have to learn to implement a second window by choosing a subject of the menuebar.
2 weeks ago

the last sourcecode is wrong.

But it's an average application with getters and setters.
2 weeks ago

I get a NullPointer Exception if I click the button(awt) to tranfer a String from a JTextField.

This is Class "A" with the ActionListener:

An this is my application:

2 weeks ago

yeah, in my case it's ok.
Because I only require like these 2 types of objects, which are in different streams.

So I define an object of type "Object" and then i cast it.
The program runs okay for my needs.
2 weeks ago

Campbell Ritchie wrote: Are your input streams of different types?

yes, thats right.

Now, i handle this in the following way:

For Example:
The first ObjectOutputStream writes an Object of type String.
The second ObjectOutputStream writes an Object of Integer.

So, the first InpuStream requires an Object of type String.
And the second InputStream requires an Object of type Integer.

I have solved it in that way:

if( ! (Object = First_Object_Stream.readObject() instanceof Integer)){

String str = (String)Object;


Integer i = (Integer)Object;

2 weeks ago
At server side i worked with the "instanceof" or "!instanceof" to check if the InputStream reference is the required Object(because i have several objectstreams).
2 weeks ago
Hi community!

I wanna check if the ObjectInputstream is null or not.
If the ObjectOutputstream wants to send a null-object,  the InputStream shouldn't be invoked.

These is my code-example:


So if the string is "null" or the List<Byte>-Object is null, the OutputStream should not be invoked.


So, i wanna check if the 3. InputStream is null or not null.
If the 3. ObjectOutpuStream isn null (or the 3. ObjectInputStream gets a null-object) , the 3. ObjectInputStream should not be invoked.

Is there a solution?

Thank you very much in advance
2 weeks ago
Resolved. I've just forgot to press the "clean" button in my projects Folder.
Now, it doesn't work.

So, everything is fine.

Sorry for that thread.
3 weeks ago
if i choose the AES Cipher with the CTR-Mode, then clientA is able to decrypt the clientBs encrypted text with another initialization vector.
But I have read in my book, that both sides (clientA and clientB) need the same initialization vector to encrypt a message in CTR-Mode.

So why is it working to decrypt a message with the same key but with different initialization vectors?

Thank you in advance
3 weeks ago