In Java, when you do
int b;
b = b + 1.0;
You get a possible loss of precision error. But why is it that if you do
int b;
b += 1.0;
There isn't any error?
I'm getting the Cannot find symbol error from my code. Does anyone know what can cause this problem?
// Register JDBC driver Class.forName("net.sourceforge.jtds.jdbc.Driver"); method forName(java.Lang.String)
Class.forName("net.sourceforge.jtds.jdbc.Driver);
^
I haven't coded in java for a long time, and after coding in C, I'm having issued organizing my code for OOP. More specifically I'm not sure when to create a new method, and when to create a new class, and when to just lump everything together.
Are there some general rules or guidelines on how it should be done?
Hi,
In android, are using static variables a recommended practice?
E.g, implementing a Singleton pattern in Java, I usually do:
private static A the_instance;
public static A getInstance() {
if (the_instance == null) {
the_instance = new A();
}
return the_instance;
}
Also, when does this get cleaned up by the Android JVM?
Thank you.
I have a vector of float arrays i.e. Vector . I want to convert this to one float array i.e. move every element in every float[] within the vector to a new float[]. Am a bit puzzled on using the Java built in method vector.toArray() to do this. Any ideas pls?
While studying the Collection API, we find that some methods (add, remove,...) may throw a java.lang.UnsupportedOperationException if the current implementation of the Collection does not support those functionalities.
Is there,actually, in the JDK, a concrete Collection that does not support those methods ?
Thanks a lot for your answers.
I am using My-eclipse and doing a struts project there is no syntax error but on starting tomcat server the following error appear in console.
java.lang.ClassNotFoundException: org.apache.commons.logging.LogFactory
and
javax.servlet.UnavailableException: Parsing error processing resource path jndi:/localhost/strutspro/WEB-INF/struts-config.xml
any idea whats the problem.
This is a quesiton taken from a java exam,
How many objects are eligible for gabage collection at #1 ?
public class Main {
Integer x = 32768;
public static void main(String[] args)
{
Main m = new Main();
m = null;
// #1
}
}
I thought it just collect Integer x, does GC even collect the Main object m?
Is it safe to do connection.createStatement().executeQuery(String query);, or should each java.sql.Statement object be created and closed by "hand" on every use, even if the connection is closed in a finally block?
If multiple queries are executed in one method by one connection it would use much less code if instantiating and closing each statement wasn't strictly necessary.
I'm a little bit confused about the difference between the two. An example of the Calendar API is supposedly located here: http://samples.google-api-java-client.googlecode.com/hg/calendar-android-sample/instructions.html, but the author himself suggests using the Calendar Provider API, details about which are here: http://developer.android.com/guide/topics/providers/calendar-provider.html.
Can someone explain to me the difference between the two, and which would be better for me to use for a simple calendar app?
I'm trying to create a REST based web service with data encapsulated using JSON. My problem is when I pass the string version of JSON in the URI it turns to something like this: %7B%22coal%22:100,%22ele%22:1500.1%7D.
I'm wondering if there are any functions Java for converting between the escaped and unescaped versions so I can parse the string.
i mainly focus on the web, i think i will never create desktop applications.
so i think it's better for me to focus on typical web languages like php.
i know an advantage java has over php is multi threading though.
will php ever support this feature in the future?
thanks
Is anyone attempting to implement C# for the JVM? As a Java developer, I've been eyeing C# with envy, but am unwilling to give up the portability and maturity of the JVM, not to mention the diverse range of tools for it.
I know there are some important differences between the JVM and CLR but is there anything that is a showstopper?
Hi!
I need execute some code before Windows shutdown process each time. So, I want block Windows shutdown process for some time. How can i do it from Java or C++ Builder ?
Thanks.
i'm new to this topic ... i'm using a ThreadPoolExecutor created with Executors.newFixedThreadPool( 10 ) and after the pool is full i'm starting to get a RejectedExecutionException .
Is there a way to "force" the executor to put the new task in a "wait" status instead of rejecting it and starting it when the pool is freed ?
Thanks
Issue regarding this
https://github.com/evilsocket/dsploit/issues/159
Line of code involved https://github.com/evilsocket/dsploit/blob/master/src/it/evilsocket/dsploit/net/NetworkDiscovery.java#L150
If I want to properly exit a documentum java job (if params are invalid for example), should I use a system.exit() or is there another way to do it.
As far as I know system.exit closes the virtual machine, does it have an effect on other jobs running?
i have used html in my java class and in one case i have used username.Username is a variable which gets values dynamically. in one case its value is 'rg@bg' but here instead of d name i m getting d url which it is directed to in my jsp. how do i ensure tht d value of username comes on d display page as it is.
i have tried "@"+username. didnt work
I am pulling a long timestamp from a database, but want to present it as a Date using Tags only, no embedded java in the JSP. I've created my own tag to do this because I was unable to get the parseDate and formatDate tags to work, but that's not to say they don't work.
Any advice?
Thanks.
Now that i have learned the theory of OOPS in good number of books , and practised a little.
Still i am not comfortable when i look into OOPS being applied in some of the Open Source projs.
Can someone suggest any problem / solution kind of book , or any resources , that covers OOPS end - end. (C# , Java preferably)
What is the recommended way of setting GET query parameters on a Restlet Request object?
I think I can see how to get them out of the request using getQueryAsForm(), but how do they get set in the first place?
At the moment, I am adding them manually to the URL using a StringBuilder and java.net.URLEncoder, but it seems like there should be a better way.
the java doc describe that the constructor Date(long date) constructs a Date object using the given milliseconds time value since January 1, 1970, 00:00:00 GMT
actulely when i did new Date(0), the date is Jan 01 01:00:00 CET 1970
I don't know why it begin with 01h
according to http://java.sun.com/javase/6/webnotes/trouble/TSG-VM/html/clopts.html it should be possible to enable -XX:+HeapDumpOnOutOfMemoryError using JConsole in runtime. How?
I assume its somewhere under MBeans tab and the com.sun.management - HotSpotDiagnostic - Operations - setVMOptions ?
I want to build a sip client based on SIP Communicator - the Java VoIP and Instant Messaging client. Basically I need to plug in some how and redirect VoIP to and from my application. Where is a good place to start?
If this seems a bit vague, I do apologize.
I have the following class
public class MyClass {
private int myAttr;
public void setAttr(int a) {
myAttr = a;
Thread.dumpStack();
}
}
That way I can detect any attempt to modify myAttr. Well, almost any. It does not work when someone modifies myAttr using Field.set() method. How can I trap Java reflection usage?