Loading Classes At Program Startup?
Nov 29, 2014
At startup, the class containing your main method is loaded. It loads all classes that it needs. Each of those loaded classes loads the classes that it needs, and so on. That can take a long time for a big application, frustrating the user. You can give users of your program the illusion of a faster start with the following trick. Make sure that the class containing the main method does not explicitly refer to other classes. In it, display a splash screen. Then manually force the loading of other classes by calling Class.forName.
I'm not sure if I got this right - the tip amounts to suggesting to load all the classes altogether in the main method while displaying the splash screen?
Second, how can the main method not refer explicitly to other classes? It has to create some objects after all...
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Oct 20, 2014
I am new to Java, and last week had an assignment to create a shopping list. I made it so that I have one class use a ProductData class to load an array of objects (description, price, priority). This week I need to take that program and change it so that it includes an Interface and Abstract Class. I need to also split one class up into at least 2 others.
I am having trouble getting my thoughts together and figuring out what to put in the interface and what to put in the abstract class. I'm thinking that it might be best to split up the ProductData class up into 3 different classes: description, price, and priority. Then have an interface with a print method. Each of those 3 classes will implement the interface.
As for the abstract class, have the price and priority extend the abstract class. The abstract class will be at the same level as the interface and contain the set and get methods. Right now they are of 2 different data types: int, double. Should I make both of them Double, and then use a method to change the priority to an int?
Should price and priority inherit from description, or should they all be at the same level? I am thinking that they should be at the same level because they all describe the item in the array.
My most confusing part is that I have no clue at all on how I can load that array when each object is split up in a different class. My professor went over ArayLists last week, and we can now use them if we want, but the assignment doesn't explicitly say that we should change it to an Array List. Where does the constructor for the ProductData() go? Do I split it up into 3 different constructors?
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Oct 23, 2014
When my app starts up is it possible to create a blank xml file in the c drive? so I can use it later on down the line
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Jan 19, 2015
I've added a small program that reads from a .txt file to the windows 8 startup folder using a .bat file ... The problem I have Is I've used relative paths for text files In the program and It doesn't work unless I change them to absolute paths.
The .bat file Is basically java -cp[absolute path to program directory] ReadAFileApp . Is there something (most likely yes!) I'm missing here ?
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Mar 10, 2014
Today downloaded eclipse and for the database i installed MSSQL 2008 R2. I want to make a webpage where i started with the login credentials, how to make a webpage for the login credentials?
I need two boxes
ID:
Password:
[Submit Button]
how to make a webpage and how can i run locally should i install IIS?
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Feb 9, 2014
I would like to know why javax.faces.webapp.FacesServlet
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Aug 26, 2014
I have a UI that uses fx:include to include a handful of nodes in a StackPane. So far I have less than 10 panes and I can already notice a delay of ~3 seconds (on an older machine) when the initial scene is built. It's especially noticeable because I'm using a pre-loader with a progress bar. The progress bar runs smoothly until the pre-loader calls start() on my application. After that, the scene is built on the application thread, so the progress bar doesn't get any more updates. It looks like the progress bar freezes until the main scene is built and shown.
I was hoping I could build the main scene on the JavaFX launcher thread, but that doesn't work. I tried it and, not surprisingly, get an exception for not being on the application thread. What are the options, if any, for making an application's start up feel a bit smoother?
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Apr 29, 2015
I am working my way through "Head First Java" and typing the code in the book into Notepad++ as I go. In the first few chapters the code was simple and only had one class (main). Now the code has two or more classes. Originally I would compile the code in the Command Window by typing "javac" and the program's name. After it compiled I would execute the program by typing "java -classpath . " and the program's name. However, now when program has several classes I get the following error: Could not find or load main class. Below is a program I am having issues with... does it need to be saved as two separate files?
class DogTestDrive {
public static void main (String [] args) {
Dog one = new Dog();
one.size = 70;
Dog two = new Dog();
two.size = 8;
[Code] ....
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Apr 9, 2014
This is a simple project that i was using to test my current java knowledge (kinda like revision) and for that i used two classes to make a simple averaging program. i know i0m making it more difficult but like i said i'm testing myself but i come up with an unexpected error. Here's the code:
- 1st Class
import java.util.Scanner;
public class Main {
public static int num;
public static int total = 0;
public static int average;
[Code].....
Now the problem is after inputing the numbers it doesn't give me the average but the value of 0.
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Aug 15, 2014
The requirements are as follows:Design and implement the class Day that implements the day of the week in a program. The class Day should store the day, such as Sun for Sunday. The program should be able to perform the following operations on an object of type Day:
A. Set the day.
B. Print the day.
C. Return the day.
D. Return the next day.
E. Return the previous day.
F. Calculate and return the day by adding certain days to the current day. For example, if the current day is Monday and we add four days, the day to be returned is Friday. Similarly, if today is Tuesday and we add 13 days, the day to be returned is Monday.
G. Add the appropriate constructors.
H. Write the definitions of the methods to implement the operations for the class Day, as defined in A through G.
I. Write a program to test various operations on the class Day.Should I break down my day.java into several separate classes, one for each of the sections (previous, next, etc)?
import java.util.*;
public class MyDay
{
static Scanner readinput = new Scanner(System.in);
String day;
public MyDay(String day)
{
day = "Sunday";
[code]....
Ideally I would like to create a Gui that would have someone type in the day, and then press a button to return the next day, prior day, or have a text input to test for adding X number of days.
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Apr 5, 2015
I am trying to make a program that takes the information from the main args, and displays them as a email in another class when Java is run.
Ex.
From: PersonA
To: PersonB
Email message is here
I have gotten this far, but every time I append my "email.print()" into the next class, it never can print any of the Strings.
Main Args Class:
public class TestMessage {
public static void main(String[] args) {
Message email = new Message("Harry Morgan", "Rudolf Reindeer");
email.append("Dear so and so,");
email.append("It is my great pleasure to");
email.append("write you an email.");
email.append("");
[Code] ....
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Nov 12, 2014
I have a problem with this ascii animation program I am working on. I declared a method inside of my class AsciiAnimation extends JFrame implements ActionListener, called
package AsciiAnimation;
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import javax.swing.*;
public class AsciiAnimation extends JFrame implements ActionListener{
int currentFrame = 0;
ArrayList<String> frameList = new ArrayList<String>();
[Code] ....
Basically I just am trying to figure out how java works with me accessing those 2 data members, currentFrame and frameList inside of my first class ALL in the same package.
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Nov 15, 2011
I usually code in PHP, C++ and ActionScript.I'm trying to follow an example of how to add images to a full screen application. What he does is that he adds a JPG background image, and then 4 PNG images. I tried to do it like I always do, by writing the code by myself looking at the book. It didn't work. I searched for errors in the code, changed some things, tried different things, but it didn't work. Then I tried to use his own code, that I downloaded from his website. That didn't work either.. I tried to find another way to add an image, and I can't seem to figure out a way to implement images in any other way into this class that's written in this book.. My Java programming level isn't just high enough.
Here's the code for the file where the images load, downloaded from the authors website (I've modified the brackets and some spaces so that it becomes easier to read):
Java Code:
import java.awt.*;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
public class ImageTest extends JFrame {
public static void main(String[] args) {
DisplayMode displayMode;
[code]....
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Mar 24, 2015
how I can change my code so that somebody can actually input the specified file path, rather than having it fixed in the code. I previously used
Scanner in = new Scanner(System.in);
System.out.println("What is the filename?");
String input = in.nextLine();
File file = new File(input);
But then the program would not display the frequencies.
import java.io.File;
import java.util.*;
/*
This program will allow the user to enter in a text file name, when prompted the program will anaylser the text and display the frequencies
*/
public class AssP {
public static void main(String[] args ) {
Scanner scan;
try {
Scanner scanner = scan = new Scanner(new File("C:/Users/Mary/workspace/Assingment/src/test.txt"));
[code]....
This is my current code and I need to so the user can load their own files.
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Feb 11, 2014
I have to show a loading image which should tell some proper loading message in jsp.
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Jun 20, 2014
I have added the image in the src and bin directories and cross-checked that the name of the image file is correct..Here is the main class
import javax.swing.*;
public class apples
{
public static void main(String args[])
{
JFrame frame = new JFrame();
MyDrawPanel wid = new MyDrawPanel();
frame.add(wid);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
frame.setSize(300,300);
}
}
and here is the class that does the image adding part
import java.awt.*;
import javax.swing.*;
public class MyDrawPanel extends JPanel
{
public void paintComponent(Graphics g)
{
Image image = new ImageIcon("b.png").getImage();
g.drawImage(image,20, 20, this);
}
}
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Sep 18, 2014
So I would like to get information out of a web-API. But my question is how I do this. I guess I need to read the URL first. And parse it after but what is the best way?
For example : [URL] .....
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Jan 31, 2014
We are using an applet in our web application. The applet of our application is dependent on bouncycastle jar,bcprov-jdk15.jar and few other jar's whose size comes around 4 mb. When using the appliaction on jre7, the applet is taking too long time to load than usual time. Is there any way to place these jar's in client machine? Will it improve the performance? Is there any other way to reduce the loading time of applet apart from placing jars in client machine?
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Apr 18, 2014
How do you call classes within other classes? Or can you only call classes through the main?
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Apr 9, 2015
I want to load image in java using Html. it works in neatbeans. But if i create a jar file it not load
URL url = getClass().getClassLoader().getResource("http://www.javaprogrammingforums.com/images/sms.png");
String tab= "<html><table style='width:100%; table-layout:fixed'><tr><td style='width: 30px' rowspan=2 >
<img src='"+ url+ "' width=36 height=36/></td><td font color='#ffffff' style='width: 110px'><font size='4'>
"+namePerson+"</font></td><td font color='#ffffff'>"+myDate+"</td></tr> <tr>
<td font color='#ffffff' style='width: 110px'>"+str1+"</td></tr></table></html>";
jLabel1.setIcon(new ImageIcon(url));// it works
tmodel.addRow(new Object[] {tab}); // not works why
not work in jar file..
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Dec 26, 2014
How load dynamically load jars? Is it possible to load updated jar in my application by code? My application has to use new and modified class files but application should not be restarted.
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Oct 27, 2014
I have an assignment where I need to add an interface to an already-created program. I have an array of objects, where each object has a name, price, and priority.
In my original program (which worked), I had all of the objects in 1 class. The professor said that I should split up the name/price/priority into 3 different classes. So what I have is an array that belongs to an interface, and name/price/priority implements. But I am having trouble loading the data into the array (from another class) once I am done with loading name.
Here is what I have so far.
public class Main {
public static void main (String[] args){
Interface[] arr = new Interface[7];
Scanner keyboard = new Scanner(System.in);
System.out.println
[code]....
Line 18 in the ItemName class is giving me an error, and I know it is because arr is of type Interface, and I am trying to assign is a String. But I don't know how to do this. In my original program I was able to do arr[x].getName(); but when I do that in Main, I get errors.
how to assign to an interface array from multiple classes.
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Feb 2, 2015
Understanding the difference between static and dynamic class loading.
It will be more useful if examples are given , especially for dynamic class loading(without using reflection).
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Aug 17, 2014
import java.awt.*;
import javax.swing.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import javax.swing.JFrame;
public class Golf extends JFrame
{
boolean isRunning = true;
[Code] ....
It loads and draws fine when I am using one image. But if I un-comment the others are try to draw the background of my game as intended, nothing gets drawn. I've played around with a number of different solutions but nothing works, I've had multiple images work in previous programs doing exactly the same thing and I really don't understand whats up.
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Jun 22, 2014
package com.mkyong.persistence;
import java.util.Date;
import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
[Code] ....
Everything is working fine but in my case One customer has Many orders but when i do customer.getOrders() the child objects are not loading . I dont know why.am i missing something here im using MYSQL database
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Oct 22, 2014
We have a custom authorization in our application login page, authorization by using eToken and java (signed jar classes) and applet as login button on page. It's work fine on older and current java versions like 7u67, 7u71 but it's not work on new java version 8u25.
We write a test class named AuthControl without package, we found that problem is in .jar file path, for example:
&APPLET_VERSION. is a jar file name, uploaded using "Shared Components / Static Files - Create"
<script src="https://www.java.com/js/deployJava.js"></script>
<script>
var attributes = {code:'AuthControl',
archive:'#WORKSPACE_IMAGES#&APPLET_VERSION.', width:132, height:37}; // problem in the path to the .jar file
var parameters = { scriptable:true, mode:'login' };
var version = '1.6';
deployJava.runApplet(attributes, parameters, version);
</script>
Error is:
...
java.lang.ClassNotFoundException: AuthControl
at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Unknown Source)
at sun.plugin2.applet.Plugin2Manager.initAppletAdapter(Unknown Source)
at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
basic: load: class AuthControl not found.
...
But if we use a direct path to the jar file, it's work fine without errors, example:
<script src="https://www.java.com/js/deployJava.js"></script>
<script>
var attributes = {code:'AuthControl',
archive:'http://example.com/myapplet.jar', width:132, height:37};
var parameters = { scriptable:true, mode:'login' };
var version = '1.6';
deployJava.runApplet(attributes, parameters, version);
</script>
Why this is happens on 8 java version?
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