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TorstenH. wrote: A List is not a ordered thing.
Yes, it is. This is how the javadoc for java.util.List defines a List:
An ordered collection (also known as a sequence).
The fact that a List is ordered is what distinguishes it from other collection types such as a Bag (although Java does not actually have a Bag type out of the box).
I ran a little test to repeat the OP's example using ArrayList and it worked perfectly, exactly as expected, no exception thrown. So I think you are right, there is something else going on here, probably to do with threads - that's typically where you see ConcurrentModification, where one thread is reading the list and another thread is updating it.
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Right, a List might be ordered in some way - The objects are placed as they come in.
I don't consider that as a real order as that is only the time relevant order in which the List is filled. So Strings e.g. would be in there non alphabetical, numbers, dates and so would be mixed up.
To get a real order according to what you expect/want the objects to be in the list you need to sort them: Object Ordering @ Java Tutorials[^]
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You're using 'ordered' to mean 'sorted' there which is rather confusing, as a list does indeed preserve the order of items and therefore to me is indeed 'ordered' (unlike, say, a map).
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right, sort and order might be a bit mixed up.
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TorstenH. wrote: To get a real order according to what you expect/want the objects to be in the
list you need to sort them
No, I don't. I can add items to the list at any position I want. One way to do this is to use the overloaded add method, which allows me to specify the index position at which I want to add the item.
This allows me to add items to the list in any arbitrary order I want, even if it does not correspond to a natural sort order. For example, I can add numbers in the order 3, 1, 4, 1, 9 which are the digits of pi in sequence. But wait! I hear you cry, that's not right. So now I go back and add the digit 5 into my list at index 4 to make 3, 1, 4, 1, 5, 9. If I add the number at the end, it's wrong. If I sort it, it's wrong. I have to add it into the correct position to get the order I want and expect.
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and how do you determine what is missing or what you're searching for?
I guess one should sort to get the right order.
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Are you saying that the correct solution is always to add to the end of a list and then sort it? That inserting into a specific index position within a list is always wrong?
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no, that is your thought.
One has a List of complex Objects(e.g. cars)
A new Object should be added to the List. Position refers to an specified argument of the Objects (e.g. power of car).
It is easier to add the object to the end of the List and then to sort the List with a simple, fixed Comparator.
I don't know what you are coding, but I have seldom simple types in my Collections.
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It may be easier to add at the end of the list, but that doesn't mean it's more efficient. I'm guessing you've never heard of an insertion sort algorithm.
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please help me to find a good java proposal to my java final project.. still we are learning java @ university but they asked us to give the java final project proposal.. so im hopeless in finding a good project..if anyone have a good new idea plz let me knw..
thx..
F.R.Majeed
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Hi there,
I have an interview in a few hours for a new job which requires java technology.
I have some basic java knowledge and most things I found back in my .Net knowledge (Apache/Tomcat is similar to IIS, JVM is more or less CLR, etc...), but I was curious about the EJB specs. Are they like Session, Application and messaging objects in .NET ? That's what I gather from all the info on google, but I have the feeling that I'm missing a key point here. Most articles keep very vague in saying it makes the developer focus on the business logic eg.
So my question is, could you explain, in a nutshell, EJB (or other common java technologies) or point me to a good article (couldn't find one, not even wiki)
Many thanks.
V.
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Looking at some of these links[^] I don't think you have time.
Unrequited desire is character building. OriginalGriff
I'm sitting here giving you a standing ovation - Len Goodman
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Thanks, that was idd my problem. That's why I wanted to know if there was something similar in .Net. Then I could map my .Net knowledge with this feature.
The articles are indeed lengthy and vague imho.
V.
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The interview went unexpectedly well  .
They figured that with my experience I could learn the new technologies very quickly anyway and they seemed more interested in motivation.
V.
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what is the advance java and functon...??????
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What indeed? Please think about your question before posting, as the above makes no sense. In fact you could probably type it into Google and get a reasonable answer.
Unrequited desire is character building. OriginalGriff
I'm sitting here giving you a standing ovation - Len Goodman
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i have created one java servlet code from which i get 3 field from database table and i want to show this field on my js(java script) page in html tag like <lable>Name= and i want to show first name field from datbase infront of lable Name..
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OK, now we know what you want. What's your question?
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i have created a one java script file in that i have written a html code in boilerplate variable and ajax to call servlet .
in java servlet i have written a code for select query as to select data from database table and store tihs value in resultset
i want to store this resultset value in to javascript variable.
how i store it ???????
eg:-suppose i have table with firstname and Lastname fields and if i retrive this column in java servlet then i want this two column value to save/store in a java script variable on java script file
like var fname=????
var lname=????
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Hi, i want to implement a voice chat in java . can anyone tell how to read abd send the voice data???
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I'm working on a system and we have a problem on printing. System send an html content to the print class and we could not get a proper print page. I'm writing my codes. Please have a look..(sorry about my bad english)
PrintableEditorPane pane = new PrintableEditorPane(
html.getText());
pane.setContentType("text/html");
EditorPanePrinter pnl = new EditorPanePrinter(pane, new Paper(), new Insets(18, 18, 18, 18));
pnl.print();
---and this is my printing class
package org.esse.utility.image;
import javax.swing.*;
import javax.swing.text.View;
import javax.swing.text.Position;
import javax.print.PrintService;
import java.awt.print.*;
import java.awt.*;
import java.awt.geom.Area;
import java.awt.geom.AffineTransform;
import java.util.ArrayList;
public class EditorPanePrinter extends JPanel implements Pageable, Printable {
JEditorPane sourcePane;
Paper paper;
Insets margins;
ArrayList<pagepanel> pages;
int pageWidth;
int pageHeight;
View rootView;
public static int PAGE_SHIFT = 20;
PageFormat pageFormat;
public EditorPanePrinter(JEditorPane pane, Paper paper, Insets margins) {
initData(pane, paper, margins);
}
public void initData(JEditorPane pane, Paper paper, Insets margins) {
JEditorPane tmpPane = new JEditorPane();
tmpPane.setEditorKit(pane.getEditorKit());
tmpPane.setContentType(pane.getContentType());
tmpPane.setText(pane.getText());
this.sourcePane = tmpPane;
this.paper = paper;
this.margins = margins;
this.pageWidth = (int) paper.getWidth();
this.pageHeight = (int) paper.getHeight();
pageFormat = new PageFormat();
paper.setImageableArea(0, 0, paper.getWidth(), paper.getHeight() );
pageFormat.setPaper(paper);
doPagesLayout();
}
public void doPagesLayout() {
setLayout(null);
removeAll();
this.rootView = sourcePane.getUI().getRootView(sourcePane);
sourcePane.setSize(pageWidth - margins.top - margins.bottom, Integer.MAX_VALUE);
Dimension d = sourcePane.getPreferredSize();
sourcePane.setSize(pageWidth - margins.top - margins.bottom, d.height);
calculatePageInfo(); int count = pages.size();
this.setPreferredSize(new Dimension(pageWidth * 2 + 50, PAGE_SHIFT + count * (pageHeight + PAGE_SHIFT)));
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
AffineTransform old = ((Graphics2D) g).getTransform();
((Graphics2D) g).setTransform(old);
}
protected void calculatePageInfo() {
pages = new ArrayList<pagepanel>();
int startY = 0;
int endPageY = getEndPageY(startY);
while (startY+pageHeight-margins.top-margins.bottom <
sourcePane.getHeight() * ( pageWidth /
sourcePane.getPreferredSize().getWidth()) / 1.8) {
Shape pageShape = getPageShape(startY, pageWidth - margins.left - margins.right, pageHeight - margins.top - margins.bottom, sourcePane);
pages.add(new PagePanel(startY, endPageY, pageShape));
startY = endPageY;
endPageY = getEndPageY(startY);
}
Shape pageShape = getPageShape(startY, pageWidth - margins.left - margins.right, pageHeight - margins.top - margins.bottom, sourcePane);
pages.add(new PagePanel(startY, endPageY, pageShape));
int count = 0;
for (PagePanel pi : pages) {
add(pi);
pi.setLocation(PAGE_SHIFT, PAGE_SHIFT + count * (pageHeight + PAGE_SHIFT));
count++;
}
}
protected int getEndPageY(int startY) {
int desiredY = startY + pageHeight - margins.top - margins.bottom;
int realY = desiredY;
for (int x = 1; x < pageWidth; x++) {
View v = getLeafViewAtPoint(new Point(x, realY), rootView);
if (v != null) {
Rectangle alloc = PrintApp.getAllocation(v, sourcePane).getBounds();
if (alloc.height > pageHeight - margins.top - margins.bottom) {
continue;
}
if (alloc.y + alloc.height > desiredY) {
realY = Math.min(realY, alloc.y);
}
}
}
return realY;
}
protected View getLeafViewAtPoint(Point p, View root) {
return getLeafViewAtPoint(p, root, sourcePane);
}
public static View getLeafViewAtPoint(Point p, View root, JEditorPane sourcePane) {
int pos = sourcePane.viewToModel(p);
View v = sourcePane.getUI().getRootView(sourcePane);
while (v.getViewCount() > 0) {
int i = v.getViewIndex(pos, Position.Bias.Forward);
v = v.getView(i);
}
Shape alloc = PrintApp.getAllocation(root, sourcePane);
if (alloc.contains(p)) {
return v;
}
return null;
}
public static Shape getPageShape(int pageStartY, int pageWidth, int pageHeight, JEditorPane sourcePane) {
Area result = new Area(new Rectangle(0, 0, pageWidth, pageHeight));
View rootView = sourcePane.getUI().getRootView(sourcePane);
Rectangle last = new Rectangle();
for (int x = 1; x < pageWidth; x++) {
View v = getLeafViewAtPoint(new Point(x, pageStartY), rootView, sourcePane);
if (v != null) {
Rectangle alloc = PrintApp.getAllocation(v, sourcePane).getBounds();
if (alloc.y < pageStartY && alloc.y + alloc.height > pageStartY) {
if (!alloc.equals(last)) {
Rectangle r = new Rectangle(alloc);
r.y -= pageStartY;
result.subtract(new Area(r));
}
}
last = alloc;
}
}
last = new Rectangle();
for (int x = 1; x < pageWidth; x++) {
View v = getLeafViewAtPoint(new Point(x, pageStartY + pageHeight), rootView, sourcePane);
if (v != null) {
Rectangle alloc = PrintApp.getAllocation(v, sourcePane).getBounds();
if (alloc.y < pageStartY + pageHeight && alloc.y + alloc.height > pageStartY + pageHeight) {
if (!alloc.equals(last)) {
Rectangle r = new Rectangle(alloc);
r.y -= pageStartY;
result.subtract(new Area(r));
}
}
last = alloc;
}
}
return result;
}
//pageable methods
public int getNumberOfPages() {
return pages.size();
}
public PageFormat getPageFormat(int pageIndex) throws IndexOutOfBoundsException {
return pageFormat;
}
public Printable getPrintable(int pageIndex) throws IndexOutOfBoundsException {
return this;
}
public int print(Graphics g, PageFormat pageFormat, int pageIndex)
throws PrinterException {
if (pageIndex < pages.size()) {
pageFormat.getPaper().setImageableArea(0, 0, paper.getWidth(), paper.getHeight());
pages.get(pageIndex).isPrinting = true;
pages.get(pageIndex).paint(g);
pages.get(pageIndex).paintAll(g);
pages.get(pageIndex).isPrinting = false;
return PAGE_EXISTS;
}
return NO_SUCH_PAGE;
}
class PagePanel extends JPanel {
int pageStartY;
int pageEndY;
Shape pageShape;
boolean isPrinting = false;
JPanel innerPage = new JPanel() {
public void paintComponent(Graphics g) {
super.paintComponent(g);
AffineTransform old = ((Graphics2D) g).getTransform();
//double scales = pageWidth
/ sourcePane.getPreferredSize().getWidth();
//scales = scales / 1.8;
Shape oldClip = g.getClip();
Area newClip = new Area(oldClip);
if (isPrinting) {
newClip = new Area(pageShape);
} else {
newClip.intersect(new Area(pageShape));
}
g.setClip(newClip);
g.translate(0, -pageStartY);
//((Graphics2D) g).scale(scales, scales);
sourcePane.paint(g);
for (Component c : sourcePane.getComponents()) {
AffineTransform tmp = ((Graphics2D) g).getTransform();
g.translate(c.getX(), c.getY());
((Container) c).getComponent(0).paint(g);
((Graphics2D) g).setTransform(tmp);
}
((Graphics2D) g).setTransform(old);
g.setClip(oldClip);
}
};
public PagePanel() {
this(0, 0, null);
}
public PagePanel(int pageStartY, int pageEndY, Shape pageShape) {
this.pageStartY = pageStartY;
this.pageEndY = pageEndY;
this.pageShape = pageShape;
setSize(pageWidth, pageHeight);
setBackground(Color.white);
setLayout(null);
add(innerPage);
innerPage.setBounds(margins.left, margins.top, pageWidth - margins.left - margins.right, pageHeight - margins.top - margins.bottom);
}
// public void paintComponent(Graphics g) {
// super.paintComponent(g);
// g.setColor(Color.black);
// g.drawRect(0, 0, getWidth() - 2, getHeight() - 2);
// }
}
public void print() {
print((PrintService) null);
}
public void print(PrintService ps) {
try {
PrinterJob pj = PrinterJob.getPrinterJob();
JFrame tmp = null;
if (this.getParent() == null) {
tmp = new JFrame();
tmp.getContentPane().add(new JScrollPane(this));
tmp.pack();
tmp.setVisible(false);
}
pj.setPageable(this);
if (ps != null) {
pj.setPrintService(ps);
}
// sending the document to the printer page
Boolean appliedPrint = pj.printDialog();
if(appliedPrint)
pj.print();
if (tmp != null) {
tmp.dispose();
}
} catch (PrinterException e1) {
e1.printStackTrace();
}
}
}
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Waaaaaaaaay too much code. The least you could do is format it as a <code> block.
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