我是stackoverflow和Java编程的新手，虽然我确实有一些小的编程背景。
我正在使用JavaFX 8.0.0-b132和JavaSE 8构建一个小程序......
程序有一个GUI，这个GUI有一个ChoiceBox。布局的架构是： AnchorPane - VBox - TitledPane - GridPane - HBox - ChoiceBox
我已经使用CSS广泛修改了ChoiceBox。
除了一个问题外，一切都正常：
当我第一次启动程序并打开ChoiceBox（每次单击鼠标或使用show（））时，它将在底部边缘显示它的ContextMenu;然而，当我关闭并再次打开它（用鼠标或编程）时，它将在ChoiceBox打开按钮（错误的y位置）的顶部显示ContextMenu，这样当前所选单元格的底部与打开的底部重合 - 按钮（意思是在我选择另一个单元格后再次打开它会改变位置）。
如何防止这种情况并使ContextMenu始终显示在底部，就像它最初一样？ 以下是受影响控件的程序GUI部分片段：
编辑：问题解决了：显然这种行为是预期的ChoiceBox行为;我在JavaFX论坛上发帖表示，最好从一开始就让弹出窗口表现得更好，即第一次打开弹出窗口以免出现错误。
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.scene.input.MouseEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.scene.text.*;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.AnchorPane;
import javafx.stage.Stage;
import javafx.geometry.Insets;
import javafx.collections.*;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.geometry.Side;
public class bugdemo extends Application {
// Elements needed in both threads
RadioButton radioBoxersOne = new RadioButton("One");
RadioButton radioBoxersTwo = new RadioButton("Two");
TextField warmupText = new TextField("skip warm up");
TextField noCyclesText = new TextField("3");
TextField cycleTimeText = new TextField("45");
TextField restingTimeText = new TextField("30");
String[] warmupTFtext = {"skip warm up", "\u00FCberspringen"};
public static void main(String... args) {
launch(args);
}
@Override
public void start(Stage primaryStage) {
// root container
AnchorPane anchor = new AnchorPane();
// Options TitledPane
GridPane trainingOptions = new GridPane();
ToggleGroup toggleGroup = new ToggleGroup();
radioBoxersOne.setToggleGroup(toggleGroup);
radioBoxersTwo.setToggleGroup(toggleGroup);
radioBoxersOne.setSelected(true);
HBox hbToggle = new HBox(15, radioBoxersOne, radioBoxersTwo);
hbToggle.setPadding(new Insets(5,0,0,0));
ObservableList<String> langList = FXCollections.observableArrayList("English", "Deutsch");
ChoiceBox<String> langBox = new ChoiceBox<String>(langList);
langBox.setValue("English");
HBox hbLangBox = new HBox(0, langBox);
hbLangBox.setPadding(new Insets(5,0,0,0));
Label warmupOptionsLabel = new Label("Warm up time (min): ");
Label noCyclesOptionsLabel = new Label("Number of cycles: ");
Label cycleOptionsLabel = new Label("Cycle time (sec): ");
Label restingOptionsLabel = new Label("Resting time (sec): ");
Label noBoxersOptionsLabel = new Label("Number of boxers: ");
Label langOptionsLabel = new Label("Language: ");
trainingOptions.add(warmupOptionsLabel, 0, 0);
trainingOptions.add(noCyclesOptionsLabel, 0, 1);
trainingOptions.add(cycleOptionsLabel, 0, 2);
trainingOptions.add(restingOptionsLabel, 0, 3);
trainingOptions.add(noBoxersOptionsLabel, 0, 4);
trainingOptions.add(langOptionsLabel, 0, 5);
trainingOptions.add(warmupText, 1, 0);
trainingOptions.add(noCyclesText, 1, 1);
trainingOptions.add(cycleTimeText, 1, 2);
trainingOptions.add(restingTimeText, 1, 3);
trainingOptions.add(hbToggle, 1, 4);
trainingOptions.add(hbLangBox, 1, 5);
TitledPane TPane_in = new TitledPane("Options", trainingOptions);
// Options TPane and Buttons together as UI (input)
VBox UI = new VBox(10, /* hbButtons ,*/ TPane_in);
anchor.getChildren().add(UI);
AnchorPane.setLeftAnchor(UI, 25.0);
AnchorPane.setTopAnchor(UI, 100.0);
// EventHandlers for the radio-buttons
radioBoxersOne.setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent e) {
/* if (!singleBoxer){
trainingProgress.getChildren().remove(boxerLabel);
trainingProgress.getChildren().remove(boxerText);
}
changeTextFlow();
singleBoxer = true; */
}
});
radioBoxersTwo.setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent e) {
/* singleBoxer = false;
trainingProgress.add(boxerLabel, 0, 3);
trainingProgress.add(boxerText, 1, 3);
changeTextFlow(); */
}
});
// "EventHandler" for the language ChoiceBox
langBox.getSelectionModel().selectedIndexProperty().addListener(new ChangeListener<Number>() {
public void changed(ObservableValue ov, Number value, Number new_value) {
/* language = (int)new_value;
changeLanguage(); */
}
});
// initialize scene and show stage
Scene scene = new Scene(anchor, 800, 650);
primaryStage.setScene(scene);
primaryStage.setResizable(false); // resizeable on/off
// import CSS file
// scene.getStylesheets().add(Letsbox.class.getResource("Training.css").toExternalForm());
primaryStage.show();
langBox.show();
langBox.hide();
langBox.show();
}
}
在此示例中，不使用CSS，但问题仍然存在......
我尝试用以下方法修复它：
/* langBox.setOnMousePressed(new EventHandler<MouseEvent>() {
@Override
public void handle(MouseEvent e) {
ContextMenu cm = langBox.getContextMenu();
cm.show(cm.getOwnerNode(), Side.BOTTOM, 0.0, 0.0);
}
}); */
但它会抛出NullPointerException ...
请告诉我如何解决这个问题：）
答案 0 :(得分：-1)
public class Main extends Application{
public static void main(String[] args) {
launch(args);
}
@Override
public void start(Stage stage) {
Scene scene = new Scene(new Group(), 450, 250);
Button notification = new Button();
notification.setPrefSize(80, 60);
notification.setAlignment(Pos.CENTER);
MenuItem item1 = new MenuItem("About");
item1.setOnAction(new EventHandler<ActionEvent>() {
public void handle(ActionEvent e) {
System.out.println("About");
}
});
MenuItem item2 = new MenuItem("Preferences");
item2.setOnAction(new EventHandler<ActionEvent>() {
public void handle(ActionEvent e) {
System.out.println("Preferences");
}
});
MenuItem item3 = new MenuItem("About");
item1.setOnAction(new EventHandler<ActionEvent>() {
public void handle(ActionEvent e) {
System.out.println("About");
}
});
MenuItem item4 = new MenuItem("Preferences");
item2.setOnAction(new EventHandler<ActionEvent>() {
public void handle(ActionEvent e) {
System.out.println("Preferences");
}
});
MenuItem item5 = new MenuItem("About");
item1.setOnAction(new EventHandler<ActionEvent>() {
public void handle(ActionEvent e) {
System.out.println("About");
}
});
MenuItem item6 = new MenuItem("Preferences");
item2.setOnAction(new EventHandler<ActionEvent>() {
public void handle(ActionEvent e) {
System.out.println("Preferences");
}
});
MenuItem item7 = new MenuItem("About");
item1.setOnAction(new EventHandler<ActionEvent>() {
public void handle(ActionEvent e) {
System.out.println("About");
}
});
MenuItem item8 = new MenuItem("Preferences");
item2.setOnAction(new EventHandler<ActionEvent>() {
public void handle(ActionEvent e) {
System.out.println("Preferences");
}
});
final ContextMenu contextMenu = new ContextMenu(item1, item2,item3, item4,item5, item6,item7, item8);
contextMenu.setMaxSize(50, 50);
contextMenu.setOnShowing(new EventHandler<WindowEvent>() {
public void handle(WindowEvent e) {
System.out.println("showing");
}
});
contextMenu.setOnShown(new EventHandler<WindowEvent>() {
public void handle(WindowEvent e) {
System.out.println("shown");
}
});
// contextMenu.hide();
notification.setContextMenu(contextMenu);
GridPane grid = new GridPane();
grid.setVgap(4);
grid.setHgap(10);
grid.setPadding(new Insets(5, 5, 5, 5));
grid.add(new Label("To: "), 0, 0);
grid.add(notification, 1, 0);
Group root = (Group) scene.getRoot();
root.getChildren().add(grid);
stage.setScene(scene);
stage.show();
notification.addEventHandler(MouseEvent.MOUSE_CLICKED, (MouseEvent me)->{
if(me.getButton()==MouseButton.PRIMARY ){
System.out.println("Mouse Left Pressed");
System.out.println(notification.getScaleX());
System.out.println(notification.getScaleY());
System.out.println(me.getScreenX());
System.out.println(me.getScreenY());
contextMenu.show(notification,Side.TOP,0,0);
//contextMenu.show(notification,me.getScreenX(),me.getScreenY());
}else{
contextMenu.hide();
}
});
}
}