This is my first java program.
public class Myjava
{
public static void main (string args[]) {
system.out.println("hello java world");
}
}
I am getting the below error in cmd when compiling the program with command javac Myjava
Error: class name are only accepted if annotation processing is explicitly requested.
I've been tasked with processing a large dataset as part of a class assignment. One of the fields is a 24-digit unsigned hex number. I realized that, rather than storing the field verbatim in a char array of length 24, I could store the actual value of the hex number in an array only 6 chars long (I chose char over int because chars are unsigned). To do this, I wrote the following simple class to accept the hex string and convert it so that it can be stored in that manner:
private class Hex24
{
private final char[] hexAsInt = new char[6];
public Hex24(String h)
{
for(int index = 0; index < 6; ++index)
hexAsInt[index] = (char)Integer.parseUnsignedInt(h.substring(index * 4, (index + 1) * 4));
[Code] ....
Assuming all this works (haven't tested it, but I think it should), what I'm wondering is how much memory this will save me (if any) compared to just throwing everything into a char[24] array. The underlying char[6] is obviously quite a bit smaller, but objects must take up more space than just their fields since Java needs to know what kind of object it is so it can know what methods it has, etc..How to accurately compare the size of a Hex24 object to the size of a 24 character array.
I guess another option/thing I might want to compare size efficiency for is putting the char[6] along with the conversion/comparison logic directly into the classes (as fields/member methods) where I'm currently using Hex24 fields. I'd guess this is the most memory-efficient option I've come up with, but it would lead to a lot of code duplication.
Another thing I'd like to compare is the size of a String vs. the size of the equivalent char array for shortish text fields. If this difference is big enough it might be worth storing those fields as arrays rather than Strings.
I've been trying to get my program to not accept empty strings when the user inputs, but I'm having some difficulties. I've tried for loops, as well as while loops.
import java.util.Scanner;
public class GasMileage
{
/**
* displayIntro
* This method displays the introduction to the user
*/
public static void displayIntro()
[Code] .....
I am looking for a way to have a Servlet (my container is Tomcat) calling a JSP file and processing it in order to retrieve the generated HTML. The compete scenario:
I have virtual shop and whenever a purchase is being carried out, the customer is redirected to a Servlet that post-processes the purchase (list of the items, etc.)
Among all these, the Servlet is also supposed to send me an email about the new purchase. I would like to have nice designed HTML mail and not just a simple plain text notification. I thought of having a designated JSP as a view, and it will only be available from the Servlet container, for this purpose. One way is having the Servlet create an HTTPClient (or any other method of network communication) to my own host and ask for the JSP.
I wonder if there is a simpler way to ask my own container to process a JSP, since I am not really making a request to an outside web application. Something like getServletContext.processAndReturnJsp("mail.jsp")
BTW, if you think my approach is too cumbersome to fill an email with HTML code, it would be great to know of a simpler way.
I am currently working on a module where huge amount of data needs to be sent to the weblogic server. The limit on Weblogic-> Server - > Protocols is 10MB.
The huge data is coming when i try to add more than 20 rows to the Ajax request.
There are possible two solutions for this
1) Increase the limit on Weblogic server to 1Gb which might lead to server crash when two or more users are trying to add 100 records at the same time.
2) Send memory in the form of chunks of (length of a row) every time I add a row. Store this in session and upon form submission retrieve from session. This cannot work if there are more than 20 users doing load testing as increase in session data decrease performance gradually.
I need that data passed to my server without any performance or errors.Currently its showing weblogic.socket.MaxMesssageSizeExceededException and RequestURI too long errors.
The super keyword when used explicitly in a subclass constructor must be the first statement but what about if i have a this(parameters) statements ? As the this one must also be the first statement... Does this means that i can have only one or the other ? What about when the super constructor is not explicit (aka implicit ) , can i use the this( parameters) in the same constructor ?
View Replies View RelatedCan we use EJB @Asynchronous annotation in distribute environment. I know we can use it but I want to know its Advisable or not. Because It's not advisable to manage user thread in Distribute environment like EJB container .Earlier if we want to make Asyn call then we use JMS. But now they added @Asynchronous annotation with Future Class to achieve the same result.
View Replies View RelatedI don't seem to be hitting my RESTful webservices. I am using Hibernate and checked and all my entity classes are working. I've even retrieved data from the database but I cannot hit the web service. I am using Tomcat 7 and Eclipse IDE.
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>HibEx1</groupId>
<artifactId>HibEx1</artifactId>
[Code] .....
I have a web xml but there is really nothing in it. The url i am wanting to hit is [URL] ..... Is this a correct URL?
I also tried changing my Path to "/service" and that did not work either. I am getting a Http Status 404 "The requested resource is not available.
i have one html page through which i want to go to servlet page but after submit it give the http 404 error.
i am using tomcat apache server.
For some reasons my servlet doGet method is being called twice. I am calling servlet from the index.jsp page by using servlet annotation "/Profile/*. And it passes path as localhost:1919/Profile/username to getPost method.
<li><a href="Profile/<%=lg.getUsername()%>">Your Profile</a></li>
Servlet Profile retrieves data from the java container stores it as an attribute and forwards to profile.jsp page.
rd = request.getRequestDispatcher("/profile.jsp");
request.setAttribute("ProfileInfo", proInfo);
rd.forward(request, response);
My profile.jsp page uses java code to show all the data (and it shows it perfectly). But then I click link to the next update_profile.jsp page. Just simple link. Then I realize that on this step for strange reasons for me doGet method from Profile servlet is called the second time. And passes path as localhost:1919/Profile/update_profile.jsp
Here is my profile.jsp code:
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@ page import="uk.ac.dundee.computing.aec.instagrim.containers.*" %>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
[Code] ....
And update_profile.jsp file is just simple file with <h1>hello</h1> output. I have looked in the internet that this might be a mapping problem or my css relative path connection problem. As you see I have commented out my css connection and problem still exists. My run output in the IDE also shows these errors:
org.apache.jasper.JasperException: An exception occurred processing JSP page /profile.jsp at line 27
24: %>
25: <article>
26:
27: <h2>User: <%=proInfo.getUsername()%>
28: </h2>
29:
30: <h3>First name: <%=proInfo.getFirstname()%>
Stacktrace:
at org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:568)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:335)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
[Code] .....
And my tomcat run configuration settings: [URL] .... and [URL] ....
So I have a screen I click on. The "webPage" comes back as the requested resource unavailable.
What I don't get is that when I run the server locally on my machine it works just fine. But when this is deployed out to server I get the error. The screen comes up but the data doesn't show up. Where should I look to troubleshoot this?
@RequestMapping(value = "/webPage_data", method = RequestMethod.GET)
public @ResponseBody
DataTableDto pastControllerDataFeed(Model model) {
I have a very simple login form. However, I keep getting http: status 404 -/login
login.jsp
<form action="/login" method="post">
<input type="text" name="username"/>
<input type="submit" name="submit"/>
</form>
[Code] ....
I have configured form based JAAS in my app. Basically, in web.xml I have declared security constraints on certain jsp page, declared specific roles, login and error pages. So, my login form is:
<form id="loginForm" action="j_security_check" method="post">
<p>
<label for="name">Username</label> <input name="j_username"
id="username" type="text" required/>
[Code] ....
This works fine when some user tries to access some of the pages declared in <security-constraint> tag of web.xml.
Container automatically manages login process, redirects to login page and if login details are valid, gives access to secured page.
Now, how should I implement login system so that user can go to login page (possibly same login form) and log in from there?
I need to track the client IP address from where user requested to my application.
I tried following:
request.getHeader("HTTP_X_FORWARDED_FOR"));
request.getHeader("X-Forwarded-For"));
request.getHeader("Proxy-Client-IP"));
request.getHeader("WL-Proxy-Client-IP"));
request.getHeader("HTTP_CLIENT_IP"));
request.getHeader("HTTP_X_FORWARDED_FOR"));
request.getRemoteAddr());
String ip = InetAddress.getLocalHost().getHostAddress();
In which InetAddress is giving my local machine IP when i run my application in localhost, but I mapped localhost:8080 with IIS server then InetAddress not giving exact IP address. How can we resolve this?
I have been recently been working on a library to handle loading and saving settings in a Java application using annotations. Here is how the library is used currently:
package main;
import dhuk.settings.main.SettingsManager;
import dhuk.settings.main.SettingsTarget;
public class Main{
public final String keybinds = "keybinds.txt", settings = "settings.txt"; // Constant strings to be used as the file's paths
SettingsManager sm = SettingsManager.instance; // Singleton used to manage all of the settings files.
[Code] .....
Here is a link to my bitbucket repository: Click Here
I am working on a program that simulates a bug moving along a horizontal line, My code works correctly when I test it in it's own class but when I tried testing my constructor and methods in a test class I received an error saying, "package stinkBug does not exist" on lines with my methods. However, stinkbug is not a package.
Java Code:
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
[code]....
I've 3 classes.
1. Circle
2. GetInputFromUser
3. testCircle
package ABC;
public class Circle {
private double radius;
public double getRadius() {
return radius;
[Code] .....
In the testCircle class, in the line: getRadius = ui1.GetInput();
It's showing the error: The method GetInput(float) in the type GetInputFromUser is not applicable for the arguments ()
And when I do: getRadius = ui1.GetInput(rad);
It's showing the error: rad cannot be resolved
I'm just wondering whether it is possible to use images as a button in Java. I have two images that I want to use to create a rollover effect, is this possible? And then I would like to reset my java program when the button is clicked, is this also possible?
View Replies View RelatedI'm relatively new to java and to image processing ... What I've done so far is make a simple application which opens the webcam and can take and save a picture. Ive then loaded the image pixel data into a 2d array. How then do I do what is known as 'fast fourier transform' on it from here?
View Replies View RelatedI'm writing a simple queue program using a netbeans as a GUI program I've used netbeans GUI editor to create the GUI my main problem was I've written the queuing code to a button function it works but it runs only once and the queue becomes empty on the second run. So I implemented a class which will create the queue outside the button click event but when I do that I get a Symbol not found: method error . The place where I get the error:
addStd1.setText("Add Student");
addStd1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
addStd1ActionPerformed(evt);
}
My button function with the class:
class stdQueCls{
Queue stdQue;
public stdQueCls(){
stdQue = new LinkedList();
}
private void addStd1ActionPerformed(java.awt.event.ActionEvent evt) {
[code]....
The code below keeps giving me errors at runtime.
import java.util.*;
import javax.mail.*;
public class SendSmtp
{
public static void main(String [] args)
{
Properties properties = new Properties();
properties.setProperty("mail.smtp.host", "localhost");
Session mailSession = Session.getDefaultInstance(properties, null);
}
}
My intention is to send email locally on a Dovecot SMTP server using Postfix. I compile it with the command:
javac SendSmtp.java -cp /usr/share/java/geronimo-javamail-1.4-spec.jar
and run it with the command:
java SendSmtp
but I keep getting the error message:
Exception in thread "main" java.lang.NoClassDefFoundError: javax/mail/Session
at SendEmail3.main(SendEmail3.java:15)
Caused by: java.lang.ClassNotFoundException: javax.mail.Session
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 1 more
I am new to Java/OOP in general, and am trying to implement a multi-threaded system that contains a master thread, and a set of worker threads that are heterogeneous in the work they do. Once they complete the work, the workers indicate to the master by posting the result on to its queue. Here is the problem. The results of each type of work is different, and the master has to process each differently. In C (which I'm familiar with), this can be achieved by having a message type that is a union of all the expected messages, and by using a switch statement.
I thought of doing something similar in Java, by using instance of on each incoming message (each individual message class having been subclassed from a super message class) , and doing switch on that, but it doesn't seem to be the OO way to do things. The only other way I could think of was to implement an abstract method to get the type of each message, and then use the type in a switch statement, or if-then-else. Is there some other Java idiom to do this kind of processing? Also, if this is an acceptable method, why is it superior to using the reflection to find out the message type (instead of using the abstract getType())?
The message types look similar to the code below:
abstract class Message {
abstract String getType();
} class Result1 extends Message {
ResultType1 content;
String getType() {
[Code] ....
I am trying to process an array of pixels, checking each within a 5*5 mask. Ive declared my mask as a 2d array and get the pixel values within a nested for loop. Im getting an ArrayIndexOutOfBoundsException at the line:
mask[0][4] = dsIm.red[i-1][j+3];
Have I declared my mask wrong for a 5*5 mask. Is my logic wrong?
I won't give all the code, but basically Im trying to check all 25 pixel values within the mask:
int [][] mask = new int[5][5];
System.out.println("We are in the method just written");
//loop one loop
for(int i = 1; i <= h-2; i++)
{
for(int j = 1; j<=w-2; j++)
[Code] .....
can we use java programming for image processing. if yes then how do we do it?
View Replies View RelatedI am looking for the ability, on the server side, to run programs or "jobs" in a job queue, where the jobs are processed as first in first out. If you are familiar with the IBM iSeries, they have a built in job queue mechanism which accomplishes what I am looking for. The primary purposes for this would be to process and update large amounts of data in a thread safe environment.
View Replies View RelatedI am writing a program that should take a url and scan the page for any links. It is in the beginning stages, but I ran into an error when I tried to extend a class. There's a lot going on in this code, but the error is caused by the constructor.
Error message at compile time:
"constructor Page in class Page cannot be applied to given types;
{//Constructor
^
required: String
found: no arguments
reason: actual and formal argument lists differ in length".
Here's the code(first my class, then the class I extended)
public class SearchEngine extends Page {
public static Color customGreen = new Color(69, 194, 33);
public static Color customYellow = new Color(232, 166, 12);
public static Color customBlue = new Color(25,97,255);
public static Color customYellowComp = new Color(178,125,0);
[code]...