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Tag: java

What is more efficient: System.arraycopy or Arrays.copyOf?

The toArray method in ArrayList, Bloch uses both System.arraycopy and Arrays.copyOf to copy an array. How can I compare these two copy methods and when should I use which? Answer The difference is that Arrays.copyOf does not only copy elements, it also creates a new array. System.arraycopy copies into an exis…

Java, server client TCP communication ends with RST

I’m trying to figure out if this is normal. Because without errors, a connection should be terminated by: I get this at the end of a TCP connection (over SSL, but i also get it with non-encrypted): The client exits normally and reaches socket.close, shouldn’t then the connection be shut down norma…

Java heap size – will this work?

I try this with NetBeans desktop application template – increasing heapsize (to 512 MiB) of executed .jar file. (I believe that NetBeans uses Singleton app by default – SingleFrameView) Will it work? Answer Not going to work. The heap space is set from the -Xmx parameter at JVM initialization time…

Convert xml to java

How can I convert xml to java so that it could read the xml document and put it in to a database? Answer Check this: http://www.java-tips.org/java-se-tips/javax.xml.parsers/how-to-read-xml-file-in-java.html That’s how you read xml file. Then you just crate SQL query to insert it into database (JDBC?)

How to set arrayList size as null?

Why the size of the arrayList choice is 5 when all the elements have been set to null Answer Because the ArrayList still contains 5 Objects. They are null, but they are objects, thus present in the list! You can empty the ArrayList, by calling choice.clear();

Java – Get a list of all Classes loaded in the JVM

I would like to get a list of all the classes belonging to a certain package as well as all of their children. The classes may or may not be already loaded in the JVM. Answer Well, what I did was simply listing all the files in the classpath. It may not be a glorious solution, but it works reliably

Creating custom URI scheme using URI class

I need to create a custom URI scheme for my project. i.e urn:myprotocol:{p1}:{p2}:{p3}:{p4} – opaque representation myprotocol://{p1}/{p2}/{p3}/{p4} – hierarchical representation. How can I add my scheme to Java URI class? Or, how can I make Java URI to understand my scheme, so I could use it in m…