I am programming using Java. I am trying write code which can recognize if the user presses the enter key in a console based program. How can I do this using java. I have been told that this can be done using either Scanner or, buffered input reader. I do not understand(or know how to use) buffered input read…
Java – using recursion to create all substrings from a string
The following code in Java uses recursion to create all possible substrings from a string. I am wondering is there a better way of coding this? I want to use recursion. FAQ Q – Why do I want to do this using recursion? A – Because the CEO of StackOverflow says recursion is important http://www.joe…
Wildcard pattern for RoutingAppender of Log4j2
I am trying to use the new RoutingAppender of Log4j2 to route the different logs based on the MDC (ThreadContext in Log4j2). What I want to do is the following: If MDC map has $contextId -> Append to $contextId appender (specific log) If MDC does not have $contextId -> Append to main appender (general l…
Print out elements from an Array with a Comma between the elements
I am printing out elements from an ArrayList and want to have a comma after each word except the last word. Right now, I am doing it like this: It prints out the words like this: The problem is the last comma. How do I solve it? Answer Print the first word on its own if it exists. Then print
Android: Image upload to web-service loses EXIF data
Please help, I currently upload an image to my web-service which does have the EXIF data attached to it at time of upload. When it arrives on the server, it is minus it’s exif data. Before I upload the image, it’s stored to the devices SD card to which is then decoded using the BitmapFactory class…
How to pass an action name using hyperlink in Struts 2?
I have a hyperlink named “Click for new User”. Once I click the link, I got NullPointerException instead of opening RegisterPage.jsp page. I post my code here, I can’t find my mistake index.jsp: struts.xml: Login.java(Action Class): Exception: Answer When you click on hyperlink you don’…
Java collections faster than c++ containers?
I was reading the comments on this answer and I saw this quote. Object instantiation and object-oriented features are blazing fast to use (faster than C++ in many cases) because they’re designed in from the beginning. and Collections are fast. Standard Java beats standard C/C++ in this area, even for mo…
Is it possible to install 64 bit JVM on linux so heap can be larger then 2gb?
It’s a 32 bit Ubuntu OS I want to be able to run with more than 2g of heap Answer No. A 32-bit kernel(and likely 32-bit CPU as well) cannot run a 64-bit executable for the JVM(or any other 64-bit executable/ELF) with your choice of OS and kernel.
How do I get the `.class` attribute from a generic type parameter?
The accepted answer to this question describes how to create an instance of T in the Generic<T> class. This involves passing in a Class<T> parameter to the Generic constructor and callin the newInstance method from that. A new instance of Generic<Bar> is then created, and the parameter Bar.c…
Read directory inside JAR with InputStreamReader
So, this question has been asked a million times i believed and I’ve been reading them for a couple of hours and trying several options given by some people but none of them work for me. I want to list all the files inside a directory inside the application’s JAR, so in IDE this works: That gives …