I have created a text field:
TextField tfPost = new TextField("140 character word count...");
I also have a button with a ActionEvent Handler class:
Button btTweet = new Button("Tweet");
TweetHandlerClass btTweetHandler = new TweetHandlerClass();
btTweet.setOnAction(btTweetHandler);
Here is the body of the handler class:
class TweetHandlerClass implements EventHandler<ActionEvent> {
#Override
public void handle(ActionEvent ae) {
System.out.println("Tweet button was clicked");
String newTweet = tfPost.getText();
}
}
What I need is for the string inside the TextField to be saved to a string variable when the Tweet button is clicked. How do I do this?
Variable scoping is a design question. The OP's question does not provide sufficient information to understand the full use case. One approach is to store the variable in the TweetHandlerClass. There are various rationales for and against such an approach. Nonetheless, for the specific question posed, it should suffice.
class TweetHandlerClass implements EventHandler<ActionEvent> {
private final TextField tfPost;
public TweetHandlerClass(TextField srcTxtFld)
{
this.tfPost = srcTxtFld;
}
#Override
public void handle(ActionEvent ae) {
System.out.println("Tweet button was clicked");
String newTweet = tfPost.getText();
}
}
Then, in the instantiating the Button:
TextField tfPost = new TextField("140 character word count...");
Button btTweet = new Button("Tweet");
TweetHandlerClass btTweetHandler = new TweetHandlerClass(tfPost);
btTweet.setOnAction(btTweetHandler);
If you really want the event handler to be a top-level class like that, you could give it a reference to a TextField as in #KevinO's answer. A slight variant on that would just be to have a reference to a Supplier<String>, which is more semantically what you really need:
class TweetHandlerClass implements EventHandler<ActionEvent> {
private final Supplier<String> tweetSupplier ;
TweetHandlerClass(Supplier<String> tweetSupplier) {
this.tweetSupplier = tweetSupplier ;
}
#Override
public void handle(ActionEvent ae) {
System.out.println("Tweet button was clicked");
String newTweet = tweetSupplier.get();
}
}
and then
Button btTweet = new Button("Tweet");
TweetHandlerClass btTweetHandler = new TweetHandlerClass(tfPost::getText);
btTweet.setOnAction(btTweetHandler);
This is pretty much overkill though. Normally you would just define the event handler with a lambda expression, instead of an explicit class:
Button btTweet = new Button("Tweet");
btTweet.setOnAction(e -> {
System.out.println("Tweet button was clicked");
String newTweet = tfPost.getText();
// ..
});
Related
I would like to have this functionality in my program:
I will have a user input field. When the user pressed the button, it will be added to the list, and input will be shown to the user.
The problem is, I would like to deselect/remove those input if the user wants. I could not achieve this.
Here is the code I have written so far, I have removed some functionality unnecessary for the question's scope:
public class AddUserInput extends VerticalLayout{
// The user input will be added to the this list
// later, this list will be sent to the server for some verification
private List<String> emails;
private HorizontalLayout content;
private VerticalLayout rows;
// user input field
private TextField emailField = new TextField("Enter email address");
public AddUserInput() {
content = new HorizontalLayout();
rows = new VerticalLayout();
content.setMargin(true);
Button addToListButton= new Button("Add to list");
addToListButton.addClickListener(new Button.ClickListener() {
#Override
public void buttonClick(Button.ClickEvent event) {
// When the user clicks add to list button
// The raw input will be added to the emails list
// The UI component is added to 'rows' component
rows.addComponent(addNewRow(emailField.getValue()));
}
});
content.addComponents(emailField, addToListButton, rows);
addComponent(content);
}
public Component addNewRow(String email){
HorizontalLayout newRow = new HorizontalLayout();
Button deleteRowButton = new Button("-");
deleteRowButton.addClickListener(new Button.ClickListener() {
#Override
public void buttonClick(Button.ClickEvent event) {
// I can delete from the UI by using the code below
newRow.removeAllComponents();
rows.removeComponent(newRow);
// How to remove from the email list???
}
});
emails.add(emailField.getValue());
Label lastEmail = new Label(emailField.getValue());
emailField.clear();
newRow.addComponents(lastEmail,deleteRowButton);
return newRow;
}
}
Is there any component/library that does this functionality?
I only need a text field, and adding the input to the list, and removing the list item if a user wants to.
The visualization of the code above:
You could use the NativeSelect component for managing the entered Strings.
I modified your AddUserInput-Component to use a NativeSelect and a corresponding DataProvider:
public class AddUserInput extends VerticalLayout {
private HorizontalLayout content = new HorizontalLayout();;
private NativeSelect<String> select = new NativeSelect<>("The List");
private ListDataProvider<String> dataProvider = DataProvider.ofCollection(new ArrayList<>());
private Button addToListButton= new Button("Add to list");
private Button deleteFromListButton = new Button("-");
private TextField emailField = new TextField("Enter email address");
public AddUserInput() {
select.setVisibleItemCount(5);
select.setWidth("100px");
select.setDataProvider(dataProvider);
select.setEmptySelectionAllowed(false);
deleteFromListButton.setEnabled(false);
content.setMargin(true);
addToListButton.addClickListener(new Button.ClickListener() {
#Override
public void buttonClick(Button.ClickEvent event) {
addEmailToList(emailField.getValue());
}
});
deleteFromListButton.addClickListener(new Button.ClickListener() {
#Override
public void buttonClick(Button.ClickEvent clickEvent) {
select.getSelectedItem().ifPresent(selectedItem -> removeSelectedEmailFromList());
}
});
select.addValueChangeListener(new HasValue.ValueChangeListener<String>() {
#Override
public void valueChange(HasValue.ValueChangeEvent<String> valueChangeEvent) {
deleteFromListButton.setEnabled(select.getSelectedItem().isPresent());
}
});
content.addComponents(emailField, addToListButton, select, deleteFromListButton);
addComponent(content);
}
private void addEmailToList(String email){
dataProvider.getItems().add(email);
select.getDataProvider().refreshAll();
emailField.clear();
}
private void removeSelectedEmailFromList(){
select.getSelectedItem().ifPresent(selectedItem -> dataProvider.getItems().remove(selectedItem));
select.setSelectedItem(dataProvider.getItems().isEmpty() ? null : dataProvider.getItems().iterator().next());
select.getDataProvider().refreshAll();
}
}
It looks like the following:
Would that be a possible option for you?
How to return result from event handler in javafx? I have bellow code, and how to return data from event to function showPrompt? Is it possible to recover the data for the function of the event?
public static String showPrompt(String title, String defValue){
final Stage dlgStage = new Stage();
TextField txtPromptValue = new TextField(defValue);
Button btnOk = new Button("Ok");
Button btnCancel = new Button("Cancel");
btnOk.setOnAction(new EventHandler<ActionEvent>(){
#Override
public void handle(ActionEvent arg0) {
//How to return data from event to function?
dlgStage.close();
}
});
btnCancel.setOnAction(new EventHandler<ActionEvent>(){
#Override
public void handle(ActionEvent arg0) {
//How to return data from event to function?
dlgStage.close();
}
});
//
Label lblTitle = new Label(title);
lblTitle.setFont(Font.font("Amble CN", FontWeight.NORMAL, 14));
//
VBox vbox = new VBox(lblTitle,txtPromptValue,btnOk,btnCancel);
vbox.setAlignment(Pos.CENTER);
vbox.setMinSize(300, 200);
//
Scene dlgScene = new Scene(vbox);
//
dlgStage.setScene(dlgScene);
dlgStage.initStyle(StageStyle.UNDECORATED);
dlgStage.initModality(Modality.APPLICATION_MODAL);
dlgStage.setMinWidth(300);
dlgStage.setMinHeight(200);
dlgStage.show();
}
The short answer is you can't return a value.
Why ?
This code bellow is called a callback.
new EventHandler<ActionEvent>(){
#Override
public void handle(ActionEvent arg0) {
dlgStage.close();
}
}
Callbacks have no return type, as you can see in the example above, it is void.
Callbacks are methods that you pass as an argument to another method. The other method will call you callback method when it wants. This means that callbacks are asynchronous. In your example, it calls the callback when you press the button.
In conclusion, you can't return from it using return.
What to do ?
You can call a method from your callback and sent your return value to it as an argument.
Example:
btnCancel.setOnAction(
new EventHandler<ActionEvent>(){
#Override
public void handle(ActionEvent arg0) {
YourClass.setReturnValue("This is button Cancel");
dlgStage.close();
}
}
});
Where setReturnValue is a method belonging to YourClass or an instance of it so it will retail your returned value.
Another way better approach would be to create a class that extends Stage maybe. Also in your showPrompt method you will have to block execution using showAndWait() or similar.
In conclusion, you can't create your entire Prompt from just one method.
You can't, because by the time you've opened and closed the prompt stage, the main thread will have already passed the showPrompt method.
As Andrei said, what you need to do is create your own custom PromptStage with a showPrompt API that blocks the main thread until the prompt stage is closed.
public static String showPrompt(final String title, final String defValue)
{
// This line will block the main thread
// See the "showAndWait()" API from JavaFX
final boolean result = PromptStage.showPrompt("My Prompt Stage", " ");
// And when the stage is closed, it will carry on to this piece of code
if (result)
{
return "This is button OK";
}
else
{
return "This is button CANCEL";
}
}
Or you could even create instances of your PromptDialog if you like
public static String showPrompt(final String title, final String defValue)
{
final PromptStage pStage = new PromptStage();
// This line will block the main thread
// See the "showAndWait()" API from JavaFX
pStage.showAndWait();
return pStage.getResultAsString();
}
There are very many approaches here. To be honest, I won't bother writing the whole class for you. However, do comment if you're stuck.
Another option is to pass the showPrompt(...) method a StringProperty, and update the property in your OK button's handler. The caller of showPrompt can then create the StringProperty, register a listener with it, and observe it. Something like:
public String showPrompt(String title, String defValue, final StringProperty result){
// ...
final TextField txtPromptValue = new TextField(defValue);
// ...
btnOk.setOnAction(new EventHandler<ActionEvent>(){
#Override
public void handle(ActionEvent event) {
result.set(txtPromptValue.getText());
dlgStage.close();
}
});
// ...
}
Then you call the dialog with something like:
StringProperty dialogResult = new SimpleStringProperty();
dialogResult.addListener(new ChangeListener<String>() {
public void changed(ObservableValue<? extends String> obs, String oldValue, String newValue) {
// process newValue, the value from the dialog...
}
});
showPrompt("Dialog Title", "Default value", dialogResult);
I'm looking for a way to pass fields with enter key in VerticalLayout or others. In vaadin book there an example with Shortcut and Handler listeners but I don't know how to implement that.
I'm trying this.
public class MyWindow extends Window implements Handler{
private Action action_enter; //pass fields with enter
private Action action_esc;
private TextField name, lastName;
public MyWindow(){
super("this window is opened");
VerticalLayout vLayout = new VerticalLayout();
setContent(vLayout);
center();
setModal(true);
setClosable(false);
setDraggable(false);
setResizable(false);
//actions
action_enter = new ShortcutAction("Enter key", ShortcutAction.KeyCode.ENTER, null);
action_esc = new ShortcutAction("Esc key", ShortcutAction.KeyCode.ESCAPE, null);
addActionHandler(this);
//fields
name = new TextField("Name");
lastName = new TextField("Last name");
name.focus();
vLayout.addComponent(name);
vLayout.addComponent(lastName);
}
#Override
public Action[] getActions(Object target, Object sender) {
return new Action[] { action_enter, action_esc };
}
#Override
public void handleAction(Action action, Object sender, Object target) {
/** close window with esc key */
if(action == action_esc){
close();
}
/** pass fields with enter key */
if(action == action_enter){
//here pass fields with enter key
}
}
}
any idea ?
try this way with ShortcutListener:
ShortcutListener skEnterListener = new ShortcutListener("Enter", ShortcutAction.KeyCode.ENTER, null){
#Override
public void handleAction(Object sender, Object target) {
if (target instanceof VerticalLayout) { // VerticalLayout or other
// sending fileds here
}
}
};
addShortcutListener(skEnterListener);
change focus of TextField using Enter instead Tab:
final TextField tf1 = new TextField("tf1");
tf1.setId("tf1");
final TextField tf2 = new TextField("tf2");
tf2.setId("tf2");
ShortcutListener skEnterListener = new ShortcutListener("Enter", ShortcutAction.KeyCode.ENTER, null){
#Override
public void handleAction(Object sender, Object target) {
if (target instanceof TextField) {
TextField field = (TextField) target;
if ("tf1".equals(field.getId())) {
tf2.focus();
}
if ("tf2".equals(field.getId())) {
tf1.focus();
}
}
}
};
addShortcutListener(skEnterListener);
There is no interface which does provide an accessor that would allow you finding out the currently focused component. Focus information can be acquired for some (but not all) field components through the com.vaadin.event.FieldEvents.FocusListener and com.vaadin.event.FieldEvents.BlurListener interfaces.
You could add for all possible fields a FocusListener and remember every time it's invoked, the current field in a variable. (Problem: not all fields provide a FocusListener.) Then when ENTER is pressed focus the next component according to the current focused field (remember the variable) that has to be focused (with the help of a simple List, LinkedList, Map, switch-case and so forth). To make it even better add a BlurListener as well to know when not to focus the next field.
Hope that helps.
I'm writing a user's GUI and I want to create a method that will be create various number of buttons with previously defined names and actions. But I have no idea how to write method selection which is based on variable value. Google gives no useful information about it. Can anyone help with this or it's just impossible?
Here is some code example:
String[] actions={"testAction1","testAction2","testAction3"};
defaultDialogWindow(actions,"test1", "test2", "test3");
void defaultDialogWindow(String[] actions, String... bNames){
double layoutX = 25;
double spacing = 15;
final Stage dialogStage = new Stage();
dialogStage.initOwner(stage);
dialogStage.initModality(Modality.WINDOW_MODAL);
dialogStage.setFullScreen(false);
dialogStage.setResizable(false);
dialogStage.setHeight(100);
dialogStage.setWidth(bNames.length*100+(bNames.length-1)*spacing+2*layoutX+5);
dialogStage.setScene(new Scene(buttonBuilder(actions,spacing,layoutX,bNames)));
dialogStage.show();
}
HBox buttonBuilder(String[] actions, double spacing,double layoutX,String... bNames){
HBox lBar = new HBox(10);
final ReadOnlyDoubleProperty menuWidthProperty = lBar.widthProperty();
lBar.setAlignment(Pos.CENTER_LEFT);
lBar.setLayoutX(layoutX);
lBar.setSpacing(spacing);
for(String text : bNames){
Button newButton = new Button();
newButton.setText(text);
newButton.setFont(Font.font("Times New Roman", 22));
newButton.prefWidthProperty().set(100);
newButton.prefHeightProperty().set(50);
newButton.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent paramT) {
**HERE MUST BE ACTION CALL BASED ON bNames VALUE**
System.out.println("button pressed");
}
});
lBar.getChildren().add(newButton);
}
System.out.println(lBar.prefWidth(-1));
return lBar;
}
void testAction1(){
System.out.println("this is test action one");
}
void testAction2(){
System.out.println("this is test action two");
}
void testAction3(){
System.out.println("this is test action three");
}**strong text**
Use HashMap:
Map<String, Runnable> actions2methods = new HashMap<>;
actions2methods.put("Action1", new Runnable { public void run() { testAction1(); }));
You can even make this easier if your actions would be Runnable instead of methods from the start.
You can use the actionCommand property of the ActionEvent to communicate which action was taken. This defaults to the label of the button but can also be set (without affecting the label) using Button.setActionCommand().
newButton.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent paramT) {
String actionCmd = paramT.getActionCommand();
if (actionCmd.equals("A")) {
doA();
} else if (actionCmd.equals("B")) {
doB();
}
System.out.println("button pressed");
}
});
http://docs.oracle.com/javase/6/docs/api/java/awt/Button.html#setActionCommand%28java.lang.String%29
http://docs.oracle.com/javase/6/docs/api/java/awt/event/ActionEvent.html
TextField f = new TextField();
Button b = new Button("Save");
b.setClickShortcut(KeyCode.ENTER); // For quick saving from text field itself
TextArea longText = new TextArea(); // "Enter" is garbled here
Hot to make the shortcut to work only in the from text field?
Use focus and blur listeners to remove and add the shortcut key:
f.addFocusListener(new FocusListener() {
#Override
public void focus(FocusEvent event) {
b.setClickShortcut(KeyCode.ENTER);
}
});
f.addBlurListener(new BlurListener() {
#Override
public void blur(BlurEvent event) {
b.removeClickShortcut();
}
});
Newer versions of Vaadin require the following code as addListener() is deprecated now.
f.addFocusListener(new FocusListener() {
private static final long serialVersionUID = -6733373447805994139L;
#Override
public void focus(FocusEvent event) {
b.setClickShortcut(KeyCode.ENTER);
}
});
f.addBlurListener(new BlurListener() {
private static final long serialVersionUID = -3673311830300629513L;
#Override
public void blur(BlurEvent event) {
b.removeClickShortcut();
}
});
Talking in terms of Vaadin 14,
I was looking for the answer and for me, this worked well
Button search = new Button("Search");
search.addClickShortcut(Key.ENTER);
As of Vaadin 23 (and probably for sometime before) the requirements have changed again.
private ShortcutRegistration primaryShortCut;
void customShortCutHandling()
{
myTextAreaField.addFocusListener((e) ->
{
System.out.println("disable");
primaryShortCut = primaryButton.addClickShortcut(Key.ENTER);
});
myTextAreaField.addBlurListener((e) ->
{
System.out.println("enable");
primaryShortCut.remove();
});
}
}
This code assumes that primaryShortCut was set when the form is created.