I am having an issue in my Swing app where I am creating a simple JList by passing it a model - and even though the model is demonstrably populated, the JList refuses to display it's own model's contents.
DefaultListModel dlm = new DefaultListModel();
String[] modelElems = {"Apple", "Orange", "Banana"};
for(int i = 0; i < modelElems.length; i++)
dlm.add(i, modelElems[i]);
JList lstFruitList = new JList(dlm);
lstFruitList.setVisible(true);
When my Swing app runs, I see the JList on screen, but it is completely empty! I've looked at countless examples, poured over the Swing tutorials, and cannot seem to figure out what is going on. Anybody ever had this happen to them before?!? Anything that is glaringly-obviously-wrong?!?
NOTE:
The following print statement indeed shows that my model has 3 elements:
// Prints "Fruit List model has a size of 3"
System.out.println("Fruit List model has a size of " + dlm.size());
However, if I try to loop through and print the names of the fruits in my model, by calling (String)dlm.get(i) at every iteration (where i is the iteration var), it prints each model element as null...
hmmmm
That code works fine for me. Some thoughts:
I see that you call the setVisible on the JList, how exactly are you adding it to whatever you are displaying?
Are you adding the elements after you display your JFrame? If I remember correctly, that won't work well, I think you have to repaint everything.
Make sure that you're not messing around with the list model at some point; Maybe at some point later in the code, you're changing it?
Ensure that you are actually looking at the right element; maybe your list is hidden behind something else?(try setting the background color, i.e. lstFruitList.setBackground(Color.BLUE);
Final thought, are you sure that you've compiled it properly? I've sometimes accidentally forgotten to compile, or had messed up something and was running an older version of the code and was confused as to why something didn't work.
For reference, here's the code that I ran:
import java.awt.*;
import javax.swing.*;
public class javatest{
public static void main(String[] args){
JFrame f = new JFrame("HELLO");
DefaultListModel dlm = new DefaultListModel();
String[] modelElems = {"Apple", "Orange", "Banana"};
for(int i = 0; i < modelElems.length; i++)
dlm.add(i, modelElems[i]);
JList lstFruitList = new JList(dlm);
lstFruitList.setVisible(true);
JPanel p = new JPanel();
p.add( lstFruitList );
f.add( p );
f.setLocation(0,0);
f.setSize(400,400);
f.setVisible(true);
}
}
Related
I've been writing Java SE 8 desktop application. I use Eclipse IDE, Oracle's JDK, and run it on MS Windows 10 OS.
My app draws diagrams, in short. I draw a diagram on JPanel which becomes part of JTabbedPane. It displays it well on GUI, and it is very responsive. The problem shows up when I pass the diagram on printing service. But instead of printing it on printer, I choose, "Microsoft print to PDF" service. What happens next, is that if the diagram is large, when you scroll it down, you will observe that its quality drops down. That is, grids start disappearing, new lines appear, etc.
The pic out here.
As you can see, eventually vertical grids vanish, diagonal line creeps in, and later gets even worse. And that is unwelcome.
Relevant code in here:
public final class GanttChartDiagram extends TopDiagram{
#Override
public void paintComponent(Graphics graph){
super.paintComponent(graph);
Graphics2D g2D = (Graphics2D)graph;
g2D.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);
...........
#Override
public Dimension getPreferredSize(){
return new Dimension(this.diagramWidth + 20, this.diagramHeight + 20);
}
}
}
The getPreferredSize() method identifies the size of diagram, so that the app knows how to adjust the scroll-bars accordingly to fit the diagram in. Otherwise by default it return 0, if not overridden.
That is the class where I draw the diagram.
The super-class out here:
public abstract class TopDiagram extends JPanel implements Printable {
private static final long serialVersionUID = 1469816888488484L;
#Override
public void paintComponent(Graphics graph){
super.paintComponent(graph);
};
/**
* Prints selected diagram
*/
#Override
public int print(Graphics graphics, PageFormat pageFormat, int pageIndex) throws PrinterException {
Graphics2D dimension = (Graphics2D)graphics;
dimension.translate(pageFormat.getImageableX(), pageFormat.getImageableY());
if(pageIndex < PrintingImageBuffer.getImageBuffer().size()){
dimension.drawImage(PrintingImageBuffer.getImageBuffer().get(pageIndex), null, 0, 0);
return PAGE_EXISTS;
}
else{
return NO_SUCH_PAGE;
}
}
}
Now that is where I print the diagram:
public static void printDiagram(){
new Thread(new Runnable(){
public void run(){
TopDiagram diagram = null;
if(id.equalsIgnoreCase("GanttChart")){
diagram = ganttChartDiagram;
}
final PrinterJob printer = PrinterJob.getPrinte
rJob();
printer.setJobName("Printing the "+id+" Diagram");
PageFormat format = printer.pageDialog(page);
int nowWidth = (int)diagram.getPreferredSize().getWidth();
int nowHeight = (int)diagram.getPreferredSize().getHeight();
BufferedImage buffImg = new BufferedImage(nowWidth, nowHeight, BufferedImage.TYPE_INT_ARGB);//default type
Graphics2D d = (Graphics2D)buffImg.getGraphics();
....etc..................
}
}).start();
}
Now the interesting part is this:
int nowWidth = (int)diagram.getPreferredSize().getWidth();
int nowHeight = (int)diagram.getPreferredSize().getHeight();
On the same instance of diagram, on multiple invocations of print (or within the method), it may or may not return different values. So that it was causing me some sort of Raster exception. But I managed to get rid off of that exception by invoking size method only once and reusing that size value throughout the method. So that, the size value stays the same, cause it is read only once.
Bad solution, but it works.
I would like to solve this issue too. Firstly, how come that this invocation diagram.getPreferredSize().getWidth() on the same instance of diagram obj. returns different size value? One more thing, is that I overrode this method as has been presented above. And the diagram object is created only once, no recalculations.
This is where I create the diagram obj. on Swing Worker only once per application's life-cycle.
GanttChartSwingWorker ganttSwingWorker = new GanttChartSwingWorker(GanttChartDiagram::new, tabbedPane, showPerformanceDiagramTab, ganttChartDiagramTabReady);
ganttSwingWorker.execute();
new Thread(() -> {
try{
ganttChartDiagramTabReady.await();
ganttChartDiagram = ganttSwingWorker.getGanttChartDiagram();
}catch(InterruptedException ie){ie.printStackTrace();}
}
).start();
Swing Worker part:
diagram = this.get();
JScrollPane scrollPaneChart = addScrollPane(diagram);
tabbedPane.addTab("Gantt Chart", null, scrollPaneChart, "Displays Gantt Chart Diagram");
Some diagram objects can be time consuming to create, imposes delay, so I use Swing Worker to do that.
So, in summary:
How to make the diagram to appear clean when I print/save it on pdf file in the way that I explained?
How to make the diagram size to calculate consistently as per multiple invocations? What leads to different diagram size values retrieving it from the same diagram object instance on multiple calls?
I just figured out what the problem is.
I observed that when it comes to drawing the diagram, the
paintComponent(Graphics g) method has been invoked repeatedly. It keeps redrawing the diagram over and over again. It is invoked by the system implicitly, yet my implementation had been triggering it.
And that trigger comes in the form of this.setSize(width, height) method on derived JPanel object. So that each time the paintComponent(Graphics g) re-executes, it sets the size on JPanel which yet triggers additional execution of the painComponent method. In the end, it is an infinite loop.
And that infinite execution was the cause of the problem; it was producing distorted diagram image on pdf file.
Solution: execute the setSize method only when it is needed; on initial panel set-up, or resize.
I am trying to add a navbar (just like bootstrap's) for a Spring application but am not getting the nav menu to appear on the web page!
Can anyone please tell me what's wrong here?
Below is my code:
private Panel viewContainer;
private HorizontalLayout navbar;
private Button btnHome;
private Button btnNested;
private Button createNavigationButton(String caption, final String viewName) {
Button button = new Button(caption);
button.addStyleName(ValoTheme.BUTTON_SMALL);
// If you didn't choose Java 8 when creating the project, convert this
// to an anonymous listener class
button.addClickListener(event -> getUI().getNavigator().navigateTo(
viewName));
return button;
}
#Override
protected void init(VaadinRequest request) {
final VerticalLayout root = new VerticalLayout();
root.setSizeFull();
navbar = new HorizontalLayout();
navbar.setWidth("100%");
navbar.setDefaultComponentAlignment(Alignment.MIDDLE_RIGHT);
root.addComponent(navbar);
final Label brand = new Label("Nested demo");
brand.addStyleName(ValoTheme.LABEL_H1);
brand.addStyleName(ValoTheme.LABEL_NO_MARGIN);
navbar.addComponent(brand);
navbar.setComponentAlignment(brand, Alignment.MIDDLE_LEFT);
navbar.setExpandRatio(brand, 1);
btnHome = new Button("Home", FontAwesome.HOME);
btnHome.addStyleName(ValoTheme.BUTTON_BORDERLESS);
navbar.addComponent(btnHome);
btnNested = new Button("nested", FontAwesome.COFFEE);
btnNested.addStyleName(ValoTheme.BUTTON_BORDERLESS);
navbar.addComponent(btnNested);
viewContainer = new Panel();
viewContainer.setSizeFull();
root.addComponent(viewContainer);
root.setExpandRatio(viewContainer, 1);
}
Any hint is much appreciated.
Thanks
Henri's comment is almost certainly the correct answer.
Judging by the init(VaadinRequest) code you're using a UI class.
Without setContent(some components with visible stuff in them);
you won't see anything.
'you won't see anything' happens a lot in Vaadin when you're attempting new things, or doing proof of concept stuff. IMHO it's always a good practice to start with really dumb UI stuff e.g. setContent(new Label("TODO - implement this content-xxx"));
Using browser dev-tools is also a great idea. A quick select-element should show you that the UI div is empty, and allow you to start diagnosing.
TL;DR :-
UI is a ComponentContainer, so you need to - either
setContent(myLayoutWithStuff);
or
getContent().addComponent(myStuff);
to show someStuff.
My current project is in as3, but this is something I am curious about for other languages as well.
I'm attempting to use a factory object to create the appropriate object dynamically. My LevelFactory has a static method that returns a new instance of the level number provided to the method. In the code calling that method, I am able to dynamically create the buttons to call the levels like so:
for (var i:int = 1; i < 4; i++) {
var tempbutton:Sprite = createButton("Level " + i, 25, 25 +(60 * i), start(i));
_buttons.push(button);
}
This code just creates a simple button with the given arguments (ButtonText, x, y, function). It's working fine. The buttons are created, and clicking on one of them calls this method with the appropriate argument
private function start(level:int):Function {
return function(e:MouseEvent):void {
disableButtons();
newLevel = LevelFactory.createLevel(level);
addChild(newLevel);
}
}
This is all working fine; I'm just providing it for background context. The question I have is this: Is it possible to dynamically choose the type of object that my static function returns? Currently, I have am doing it as follows
public static function createLevel(level:int):Level {
var result:Level;
switch(level) {
case 1: result = new Level1(); break;
case 2: result = new Level2(); break;
//etc
}
return result;
}
I should note that all of these Level1, Level2, etc. classes extend my base level class. (Yay polymorphism!) What I would like to do is be able to do something along the lines of
public static function createLevel(level:int):Level {
var result:Level;
var levelType:String = "Level" + level;
return new levelType();
}
Obviously it's not going to work with a string like that, but is there any way to accomplish this in as3? What about other languages, such as Java or Python? Can you dynamically choose what type of child class to instantiate?
Update:
import Levels.*;
import flash.events.*;
import flash.utils.*;
public class LevelFactory
{
public static function createLevel(level:int):Level {
var ref:Class = getDefinitionByName('Levels.' + 'Level' + level) as Class;
var result:Level = new ref();
return result;
}
}
Update/Edit: getDefinitionByName seems to be what I'm looking for, but it has a problem. It seems that the compiler will strip unused imports, which means that unless I declare each subclass in the code ahead of time, this method will get a reference error. How can I get around the need to declare each class separately (which defeats the purpose of dynamic instantiation)?
Yes, you sure can, and it's very similar to the string thing that you've provided. The only thing that you are missing is the getDefinitionByName method: http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/utils/package.html#getDefinitionByName()
You can generate whatever class name you want, and what this method does is that it searches for that class in it's namespace, and if it finds it - it returns it as a class:
var ClassReference:Class = getDefinitionByName("flash.display.Sprite") as Class;
var instance:Object = new ClassReference();
This piece of code will instantiate a Sprite. This way you can instantiate your classes without all those switches and cases, especially when you have to make a hundred levels :)
Hope that helps! Cheers!
Edit:
In your case, the code should be:
var ref:Class = getDefinitionByName('com.path.Level' + index) as Class;
var level:Level = new ref(); // it will actually be Level1 Class
Since Andrey didn't quite finish helping me out, I am writing up a more complete answer to the question after much research.
getDefinitionByName definitely has the use I am looking for. However, unlike its use in Java, you HAVE to have a hard reference to the class you want instantiated somewhere in your code. Merely imported the class is not enough; the reason for this is that the compiler will strip the reference from any unused import to save space. So if you import the package of classes you want to choose dynamically but don't have a hard reference to them, the compiler will de-reference them. This will lead to a run-time error when the program cannot find the appropriate reference to your class.
Note that you don't actually have to do anything with the reference. You just have to declare a reference so that it can be found at run-time. So the following code will work to eliminate the switch-case statement and allow me to dynamically declare which class I am using at run-time.
{
import Levels.*;
import flash.events.*;
import flash.utils.*;
/**
*
* Returns the requested level using the createLevel class
* ...
* #author Joshua Zollinger
*/
public class LevelFactory
{
Level1, Level2, Level3, Level4, Level5, Level6, Level7;
public static function createLevel(level:int):Level {
var ref:Class = getDefinitionByName('Levels.Level' + level) as Class;
var result:Level = new ref(); // it will actually be the correct class
return result;
}}}
The obvious downside to this is that you still have to have a hard-coded reference to every class that can be instantiated like this. In this case, if I try to create a Level8 instance, it will through a run-time error because Level8 is not referenced. So every time I create a new level, I still have to go add a reference to it; I can't just use the reference dynamically.
There are supposedly ways around this that I have not tested yet, such as putting the code for the classes in a separate SWF and importing the SWF at run-time or using outside libraries that will have different functionality. If anyone has a solid way to get a truly dynamic reference that doesn't require a hard coded reference anywhere, I would love to hear about it.
Of course, it's still a lot cleaner this way; I don't have a extensive switch case statement to pack all the levels. And it's easier and faster to add a reference to the list than creating a new case in a switch. Plus it is closer to dynamic programming, which is usually a good thing.
This is my first experiment using Swing with Scala, and have a few questions about my code below. All it does is to produce a window with a coloured rectangle that changes colour. Please feel free to answer one or any of the questions.
1) I used a Java ActionListener below because I couldn't work out how to get javax.swing.Timer to work as a Publisher. Is there a way to use the Scala model, i.e. listenTo() - or is this the way to do it?
2) My overridden preferredSize value in the Panel doesn't seem to work: the window comes up minimized. In my Java version I override the getPreferredSize method, but there is no such method in Panel, so I assumed this is the way to do it, but why doesn't it work?
3) paintComponent isn't documented at all in the Scala API documentation. I assume this is because it is protected access in Java, but it seems like an oversight. Am I correct to override paintComponent or is it hidden because I'm supposed to use the documented paint method instead?
4) Scala doesn't seem to have getWidth() and getHeight() methods on components - is it standard to use size.width and size.height?
import swing._
import java.awt.{Graphics, Color}
import java.awt.event.{ActionEvent, ActionListener}
import javax.swing.Timer
object ColorPanel extends SimpleSwingApplication {
private var c: Color = new Color(0)
def top = new MainFrame {
title = "Flash!"
contents = p
}
val p = new Panel with ActionListener {
override val preferredSize = new Dimension(200, 200)
override def paintComponent(g: Graphics2D) {
g.setColor(c)
g.fillRect(0, 0, size.width, size.height)
}
def actionPerformed(e: ActionEvent) {
c = new Color((c.getRGB() + 1000) % 16777216)
repaint
}
}
val timer = new Timer(100, p)
timer.start()
}
No immediate answer. But your approach is certainly ok. I don't see though why your observer should be the panel. I would create an anonymous ActionListener directly with the timer, and instead add a specific method to that panel, like def animateColor() { ... }
You can use preferredSize = new Dimension(200, 200)
According to this quasi official document, yes : http://www.scala-lang.org/sid/8 (section 6 Custom Painting)
A bit stupid indeed to instantiate a new Dimension all the time. But if you look exactly at the example the SID, it does the same, uses size.height. In super high performance code, you may want to call directly into the underlying peer (peer.getWidth)
I experienced a problem with the name property in as3, I created this "dot" movieclip and I exported to a class,
then I anonymously created a bunch of dots using a loop. I assigned numbers as name to each dots
private function callDots(num:Number):void
{
for (var i = 0; i < subImagesTotal[num]; i++)
{
var d:Dot = new Dot();
d.x = i*23;
d.y = 0;
d.name = i;
dotContainer.addChild(d]);
}
}
so far so good, I checked that if I trace the name here, I will get the number I want.
However, it's not giving me the numbers if I trace it in other functions.
I added all of my dots to "dotContainer", and if I click on one of the dots, it will call this function
private function callFullSub(e:MouseEvent):void
{
var full_loader:Loader = new Loader();
var temp:XMLList = subImages[sub];
var full_url = temp[e.target.name].#IMG;
full_loader.load(new URLRequest(full_url));
full_loader.contentLoaderInfo.addEventListener(Event.INIT, fullLoaded);
}
e.target.name is suppose to be numbers like 1 or 2, but it's giving me "instance66" "instance70" and I
have no idea why. Because I did the same thing with loaders before and it totally worked.
Any ideas? Thanks.
christine
The e.target returns the inner most object clicked on, this could be a TextField, another MovieClip or posibly a shape (I'm not 100% of the last one) inside the "Dot".
To prevent this you could try to set the mouseChildren property to false on the Dot's when you add them. This should insure that nothing inside the dots can dispatch the click event, and thus the Dot's should do it.
Perhaps you could also in the event handler verify the target type with code like this:
private function callFullSub(e:MouseEvent):void
{
if(!e.target is Dot)
throw new Error("target in callFullSub is not Dot but: " + e.target.toString());
//The rest of you code here
}
The answer is [e.currentTarget.name] I perform this all the time!
Should return "Dot1" "Dot2", etc.
If the value you wish to return is a number or other data type other than a string (name of object) use [e.currentTarget.name.substr(3,1).toString()]
Should return 1, 2, etc.
Navee
I tried to reproduce your problem first with Flex using runtime created movieClips and then with Flash using Dot movieClip symbols exported for ActionScript. Neither application exhibited the problem.
You may already know names like "instance66" "instance70" are default enumerated instance names. So, whatever is dispatching the MouseEvent is NOT the dot instance. Perhaps you are unintentionally assigning callFullSub to the wrong targets, maybe your containers? Try assigning it to dot instance right after you create them, like this:
private function callDots(num:Number):void
{
for (var i = 0; i < subImagesTotal[num]; i++)
{
var d:Dot = new Dot();
d.x = i*23;
d.y = 0;
d.name = i;
d.addEventListener(MouseEvent.CLICK, callFullSub);
dotContainer.addChild(d]);
}
}
Be sure to temporarily comment out your original assignment.
Try this might work,..
d.name = i.toString();
You have not shown enough of your code for me to be able to give you a DEFINATE answer, I will however say this.
//After you create each loader you need to set its mouseEnabled
//property to false if you do not want it to be the target of
//Mouse Events, which may be superseding the actual intended target;
var full_loader:Loader = new Loader();
full_loader.mouseEnabled = false;
//Also you could name the loaders and see if what comes back when you click is the same.
ALSO! Add this to your Mouse Event handler for CLICK or MOUSE_DOWN:
trace(e.target is Loader); //If traces true you have an answer
I believe that the mouse events are being dispatched by the Loaders.
please provide more of your code, the code where the Loader.contentLoaderInfo's COMPLETE handler fires. I assume this is where you adding the loaders to the display list as I cannot see that now.