I am performing the following action in GWT
public class FooPanel extends SimplePanel {
private String url;
public FooPanel () {
super(DOM.createAnchor());
Button button = new Button();
button.addClickHandler(new ClickHandler() {
public void onClick(ClickEvent event) {
foo();
}
});
add(button);
}
}
however when I run the code I get the following error
SimplePanel can only contain one child widget
However Button is a single widget so I am not sure what the problem is? The problem doesn't occur if i don't add the button
Remove this line:
super(DOM.createAnchor());
You don't need it.
You can simply use your Button in your code, or extend a Button widget. Adding a Button to a SimplePanel does not offer any benefits.
Have a look at source code of SimplePanel#add() to analyze this error.
#Override
public void add(Widget w) {
// Can't add() more than one widget to a SimplePanel.
if (getWidget() != null) {
throw new IllegalStateException("SimplePanel can only contain one child widget");
}
setWidget(w);
}
Now its clear from the source code that you have already added a widget in SimplePanel.
Call SimplePanel#getWidget() to get the already added widget.
Look at the source code of default constructor if SimplePanel class. It might help you to understand that how SimplePanel enclose the widget inside it.
/**
* Creates an empty panel that uses a DIV for its contents.
*/
public SimplePanel() {
this(DOM.createDiv());
}
Try with setWidget(button); instead of add(button);
Related
I created the following class as an extension of gwtbootstrap3 Tooltip. There are at least 2 reasons why I want to derive the gwtbootstrap3 Tooltip class:
1.) Add a onWindowClosing Handler when the tooltip is shown so I can hide() the tooltip when the user leaves the page (this is - as far as I understand - a feature which is also not supported in Bootstrap, is it?)
2.) I want to prevent Tooltips from being shown when the page is displayed on iPads or iPhones as they behave strange when tooltips are involved (first tip shows the tooltip , the second tip executes the button, which is not exactly what the user expects)
Please note that the class given below is still not finished ... but already at this stage I get an exception when adding a handler.
Please also note that it throws an exception no matter what type of Handler (ShowHandler, ShownHandler, etc.) I add.
Any help greatly appreciated.
package com.mypackage.client.widgets.featureWidgets;
import org.gwtbootstrap3.client.shared.event.ShowEvent;
import org.gwtbootstrap3.client.shared.event.ShowHandler;
import org.gwtbootstrap3.client.ui.constants.Trigger;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.Window.ClosingEvent;
public class Tooltip extends org.gwtbootstrap3.client.ui.Tooltip {
private boolean isMobile;
private HandlerRegistration windowClosingHandlerRegistration;
private final Tooltip tooltip;
public Tooltip() {
super();
tooltip = this;
this.addShowHandler(new ShowHandler() {
#Override
public void onShow(final ShowEvent showEvent) {
// TODO Auto-generated method stub
if (windowClosingHandlerRegistration == null) {
windowClosingHandlerRegistration = Window.addWindowClosingHandler(new Window.ClosingHandler() {
#Override
public void onWindowClosing(final ClosingEvent arg0) {
tooltip.hide();
}
});
}
}
});
}
}
When I create a instance of this tooltip using the following:
[...]
<b:ButtonToolBar ui:field="itemButtonToolBar" addStyleNames="hiddenPrint">
<b:ButtonGroup>
<a:Tooltip title="{msgs.buttomTitleAddItem}" container="body">
<b:Button ui:field="addItemButton" icon="PLUS"/>
</a:Tooltip>
[...]
I get the following exception when trying to add the Handler, why?
SEVERE: (TypeError) : Cannot read property 'addHandler_11_g$' of undefinedcom.google.gwt.core.client.JavaScriptException: (TypeError) : Cannot read property 'addHandler_11_g$' of undefined
at Unknown.addShowHandler_2_g$(meetingApp-0.js#26:57195)
at Unknown.Tooltip_6_g$(meetingApp-0.js#8:57685)
at Unknown.build_f_Tooltip2_0_g$(meetingApp-0.js#55:31606)
at Unknown.get_f_Tooltip2_0_g$(meetingApp-0.js#15:31831)
at Unknown.build_f_ButtonGroup1_0_g$(meetingApp-0.js#38:31524)
at Unknown.get_f_ButtonGroup1_0_g$(meetingApp-0.js#15:31791)
at Unknown.build_itemButtonToolBar_0_g$(meetingApp-0.js#41:31696)
at Unknown.get_itemButtonToolBar_0_g$(meetingApp-0.js#15:31876)
at Unknown.createAndBindUi_58_g$(meetingApp-0.js#91:31437)
at Unknown.createAndBindUi_59_g$(meetingApp-0.js#15:31441)
at Unknown.ItemButtonGroup_2_g$(meetingApp-0.js#56:30733)
at Unknown.$init_589_g$(meetingApp-0.js#31:37722)
at Unknown.SummaryWidget_1_g$(meetingApp-0.js#8:37686)
at Unknown.loadSummaryWidget_0_g$(meetingApp-0.js#26:4991)
at Unknown.setSummary_1_g$(meetingApp-0.js#10:5028)
at Unknown.onSuccess_8_g$(meetingApp-0.js#21:3312)
at Unknown.onSuccess_9_g$(meetingApp-0.js#8:3317)
at Unknown.onResponseReceived_0_g$(meetingApp-0.js#26:156917)
at Unknown.fireOnResponseReceived_0_g$(meetingApp-0.js#17:129224)
at Unknown.onReadyStateChange_0_g$(meetingApp-0.js#28:129532)
at Unknown.<anonymous>(meetingApp-0.js#18:172082)
at Unknown.apply_0_g$(meetingApp-0.js#28:104636)
at Unknown.entry0_0_g$(meetingApp-0.js#16:104692)
at Unknown.<anonymous>(meetingApp-0.js#14:104672)
Disclaimer: I use gwtbootstrap3 v0.9.2 and I believe it's the same version as you use as I got the same error for your code.
A Tooltip needs a Widget to operate on (in your case the Button is a Tooltip's widget). Tooltip uses it's widget to do all events handling - see source code for addShowHandler for example.
Now you need to understand how the whole structure is built:
first the Tooltip is created (wit no widget set)
then the Button is created
Tooltip's setWidget method is called to set the button as a widget
So when you use addShowHandler method in your constructor, you actually call widget.addHandler while widget is null.
You can check it by Window.alert(tooltip.getWidget() == null ? "null" : tooltip.getWidget().toString());
There are few ways to make it work (the later the better):
wait for DOM structure to be built by scheduling a deferred command (if you are sure that the widget will be eventually set):
Scheduler.get().scheduleDeferred(new ScheduledCommand() {
#Override
public void execute() {
// set up events handling
}
});
override setWidget method (note thet there are two methods: setWidget(Widget w) and setWidget(IsWidget w)):
#Override
public void setWidget(Widget w) {
super.setWidget(w);
// set up events handling
}
you don't need to addWindowClosingHandler in the showEvent handler, you can do it directly in the constructor:
public class Tooltip extends org.gwtbootstrap3.client.ui.Tooltip {
private boolean isMobile;
private final Tooltip tooltip;
public Tooltip() {
super();
tooltip = this;
Window.addWindowClosingHandler(new Window.ClosingHandler() {
#Override
public void onWindowClosing(final ClosingEvent arg0) {
tooltip.hide();
}
});
}
}
I have a gwt form which has about 70-100 widgets (textboxes,listboxes,custom widgets etc)
I am trying to implement the features of CUT ,COPY in this form .For this i have 2 buttons right on top of the form.
Now the problem i have is that when i click on the copy button , the widget that was focused in the form looses focus and i dont know which text to copy(or which widget was last focused before the focus getting to the copy button)
I was planning to implement blur handlers on all the widgets but i feel is a very laborious and not a good solution.
How can i get around this issue?
Thanks
Perhaps someone with a deeper insight might provide a better approach but I beleive adding blur handlers is perfectly valid. I do not quite see why you think it would be laborious, after all you don't need a different handler for each of your widgets, you can get away with only one(at most a couple for a variety of controls..), here is a very simple example,
public class CustomBlurHandler implements BlurHandler{
Object lastSource;
String text;
#Override
public void onBlur(BlurEvent event) {
if (event.getSource() instanceof TextBox) {
lastSource = event.getSource();
text = textBox.getSelectedText();
}
}
public Object getLastSource() {
return lastSource;
}
public String getText() {
return text;
}
}
and onModuleLoad :
public class Test implements EntryPoint {
CustomBlurHandler handler = new CustomBlurHandler();
public void onModuleLoad() {
TextBox text1 = new TextBox();
TextBox text2 = new TextBox();
text1.addBlurHandler(handler);
text2.addBlurHandler(handler);
Button b = new Button("Get last selected text");
b.addClickHandler(new ClickHandler() {
#Override
public void onClick(ClickEvent event) {
Window.alert(handler.getLastSource()+ " " + handler.getText());
}
});
RootPanel.get().add(text1);
RootPanel.get().add(text2);
RootPanel.get().add(b);
}
}
I'm new to GWT programming. So far I have a DialogBox which is supposed to collect a login and a password, which can if required launch another DialogBox that allows someone to create a new account.
The first of these two DialogBoxes always appears at the top left of the browser screen, and can't be dragged, although part of the definition of a DialogBox is that it can be dragged. However, the second DialogBox can be dragged about the screen without any problem.
What I'd really like is for the first DialogBox to appear in the middle of the screen & be draggable, both of which I thought would happen automatically, but there's not.
So, what things can stop a DialogBox from being draggable? There is nothing on the RootPanel yet. Does that make a difference?
Code fragments available if they help, but perhaps this general outline is enough for some pointers.
Thanks
Neil
Use dialogBox.center() This will center your DialogBox in the middle of the screen. Normally a DialogBox is by default draggable.
Just tried it out and it doens't matter if your RootPanel is empty our not. When I just show the DialogBox on ModuleLoad it is draggable and it is centered. Probably the problem is situated somewhere else.
This is the example of google itself:
public class DialogBoxExample implements EntryPoint, ClickListener {
private static class MyDialog extends DialogBox {
public MyDialog() {
// Set the dialog box's caption.
setText("My First Dialog");
// DialogBox is a SimplePanel, so you have to set its widget property to
// whatever you want its contents to be.
Button ok = new Button("OK");
ok.addClickListener(new ClickListener() {
public void onClick(Widget sender) {
MyDialog.this.hide();
}
});
setWidget(ok);
}
}
public void onModuleLoad() {
Button b = new Button("Click me");
b.addClickListener(this);
RootPanel.get().add(b);
}
public void onClick(Widget sender) {
// Instantiate the dialog box and show it.
new MyDialog().show();
}
}
Here more information about the DialogBox.
Without seeing any of your code it's hard to tell what's going wrong. The following code works for me (ignore the missing styling...):
public void onModuleLoad() {
FlowPanel login = new FlowPanel();
Button create = new Button("create");
login.add(new TextBox());
login.add(new TextBox());
login.add(create);
create.addClickHandler(new ClickHandler() {
#Override
public void onClick(ClickEvent event) {
final DialogBox box = new DialogBox();
FlowPanel panel = new FlowPanel();
Button close = new Button("close");
close.addClickHandler(new ClickHandler() {
#Override
public void onClick(ClickEvent event) {
box.hide();
}
});
panel.add(new Label("some content"));
panel.add(close);
box.setWidget(panel);
box.center();
}
});
DialogBox firstBox = new DialogBox(false, true);
firstBox.setWidget(login);
firstBox.center();
}
Both boxes are draggable and shown in the center of your browser window.
Looks like you're overriding this method in Widget:
public void fireEvent(GwtEvent<?> event) {
if (handlerManager != null) {
handlerManager.fireEvent(event);
}
}
In Widget, handlerManager refers to a private HandlerManager.
Either add super.fireEvent(event) to your method or as you have done rename it.
Well, with vast amounts of trial and error I have found the problem, which was just this: I had a method in an object I'd based on DialogBox called fireEvent, which looked like this:
public void fireEvent(GwtEvent<?> event)
{
handlerManager.fireEvent(event);
}
Then, when a button was clicked on the DialogBox, an event would be created and sent off to the handlerManager to be fired properly.
And it turns out that if I change it to this (LoginEvent is a custom-built event):
public void fireEvent(LoginEvent event)
{
handlerManager.fireEvent(event);
}
... or to this ....
public void fireAnEvent(GwtEvent<?> event)
{
handlerManager.fireEvent(event);
}
the DialogBox is draggable. However, if the method begins with the line
public void fireEvent(GwtEvent<?> event)
then the result is a DialogBox which can't be dragged.
I'm a bit unsettled by this, because I can't fathom a reason why my choice of name of a method should affect the draggability of a DialogBox, or why using a base class (GwtEvent) instead of a custom class that extends it should affect the draggability. And I suspect there are dozens of similar pitfalls for a naive novice like me.
(Expecting the DialogBox to centre itself was simply my mistake.)
I am having problems while adding my widget into the RootPanel of another container class. I think that it may be related to the Asynchronous call that I make during the creation of the widget. I have a main class named ImageView which implements EntryPoint. In this class, I am creating an instance of my widget named NewWidget by clicking on a button. However, I cannot display it with the traditional methods:
Here is the EntryPoint class (ImageView):
import com.mycompany.project.client.widgets.NewWidget;
public class ImageViewer implements EntryPoint {
public void onModuleLoad() {
Button b = new Button("Button");
RootPanel.get().add(b);
b.addClickHandler(new ClickHandler() {
public void onClick(ClickEvent event) {
NewWidget w = new NewWidget();
RootPanel.get().add(w);
}
});
}
And here is my widget (NewWidget):
public class NewWidget extends Composite {
final static DataServiceAsync service = (DataServiceAsync) GWT.create(DataService.class);
final FlowPanel mainPanel = new FlowPanel();
public NewWidget() {
fillImagePath();
}
public void fillImagePath(){
ServiceDefTarget endpoint = (ServiceDefTarget) service;
endpoint.setServiceEntryPoint(GWT.getModuleBaseURL() + "data");
service.getAllDocuments(new AsyncCallback<ArrayList<String>>() {
#Override
public void onFailure(Throwable e) {
Window.alert("Server call failed.");
}
#Override
public void onSuccess(ArrayList<String> paths) {
process(paths);
}
});
}
public void process(ArrayList<String> paths){
ArrayList<String> imagePath = paths;
Image img = new Image(imagePath.get(4));
mainPanel.add(img);
initWidget(mainPanel);
}
}
In this NewWidget, I am making an asynchronous call to my server in order to receive a String ArrayList, which contains 10 Strings that refer to the file path of 10 different images (i.e, "images/01.jpg", "images/02.jpg", and so on). I am pretty sure that I successfully and correctly receive these image paths. I have arbitrarily chosen index number 4 to display in my NewWidget.
The problem is that I cannot display this NewWidget in my ImageView main panel. I can easily display other widgets with this method. With many attempts, I have realized that I can display the image if I add the line RootPanel.get().add(mainPanel) at the end of NewWidget. However, I do not want to make a call that refers to the parent container (RootPanel in ImageView). Why can't I display this image with only instantiating it in my container panel, like I can display any other widget? I am pretty sure that it is related to the Asynchronous call not getting completed before I attempt to add the widget. But I don't know how to fix this.
I would be very glad if people would share their ideas. Thanks.
Move the initWidget(mainPanel) call to the first line the constructor.
I am trying to focus on a particular list view in a tree, I am using the following code
this.txtListName.setCursorPos(this.txtListName.getText().length());
this.txtListName.setFocus(true);
The text view has the cursor blinking inside it but when I type a key nothing happens, I have to select the text view again before being able to type.
Why is this happening.
SOLVED
The setting the the focus was done inside a for loop that looped over and created the Tree Items, when I removed it from the for loop it worked.
Could it be that something in your current call stack is taking the focus away after you set it. You could try setting the focus in a timeout:
(new Timer() {
#Override
public void run() {
txtListName.setFocus(true);
}
}).schedule(0);
I've tried to recreate your problem but the following snippet works for me:
public void onModuleLoad() {
Tree tree = new Tree();
final TextBox box = new TextBox();
box.setText("some content");
tree.add(box);
Button btn = new Button("set focus");
btn.addClickHandler(new ClickHandler() {
#Override
public void onClick(ClickEvent event) {
box.setCursorPos(box.getText().length());
box.setFocus(true);
}
});
RootPanel.get().add(tree);
RootPanel.get().add(btn);
}
Isn't that what you're trying to achieve?