Is there a way to invert a switch for example switch (!(x))? I’m writing a program and I only want the user to be able to input certain letters. If they input an invalid letter, they would have to input it again. I’m trying to use a switch for this avoiding doing something like because the number …
Java read file and store text in an array
I know how to read a file with Java using Scanner and File IOException, but the only thing I don’t know is how to store the text in the files as an array. Here is a snippet of my code: Here is what my KeyWestTemp.txt file contains: Answer Stored as strings: For floats:
Why does my ArrayList contain N copies of the last item added to the list?
I’m adding three different objects to an ArrayList, but the list contains three copies of the last object I added. For example: Expected: Actual: What mistake have I made? Note: this is designed to be a canonical Q&A for the numerous similar issues that arise on this site. Answer This problem has tw…
How to keep a variable value even after doing run as-> Java Application?
I know that when we use static variables the value remains the same for all the instances of a class. But when I do run as -> Java Application in a class, even the static variable is reinicialized with the default value. Is there any way to keep a variable value even after doing run as-> Java Applicatio…
How to retrieve my public and private key from the keystore we created
My task is the following: Retrieve my public and private key from the keystore I created. Use these keys to encrypt a paragraph using my RSA 2048-bit public key. Digitally sign the result using the DSA-SHA-1 signature algorithm. Save the digital signature output on a file called output.dat. The program below …
Is it bad practice to keep data in static variables?
In an Android application, is it bad practice to store objects in static fields in these cases? Application data. Is it bad to keep application data in static variables in a class while the application is running? Currently, I’m storing the data in an instance variable in my Application class. Then clas…
Unidentified developer for Java Web Start application on OS X
On Mac OS X 10.9 signed Java Web Start applications are blocked by default with the message: I know it’s possible to weaken the security checks to allow any application to run, but that requires a manual intervention of the end user. Is it possible to “sign” a Java Web Start application such…
Use jsf as template engine on EAR
Thinking about html e-mails for our e-commerce site I thought about reusing jsf and other 3rd party libraries as a template engine to create the e-mails on our application server (Glassfish 3, EAR). Is it possible to manually run jsf with a local file and initialize the necessary bean to capture the html outp…
java.lang.ClassNotFoundException: org.apache.xmlbeans.XmlObject Error
I am getting following error Exception in thread “main” java.lang.NoClassDefFoundError: org/apache/xmlbeans/XmlObject at OrderBook.WriteToExcelSheet.CreateOutPutFile(WriteToExcelSheet.java:20) at OrderBook.MainMethod.main(MainMethod.java:71) I looked for the reasons for this error online but could…
Volatile variable explanation in Java docs
when a thread reads a volatile variable, it sees not just the latest change to the volatile, but also the side effects of the code that led up the change This is mentioned at http://docs.oracle.com/javase/tutorial/essential/concurrency/atomic.html Can someone please provide an example of this? This first gave…