java JavaFX |带示例的上下文菜单

JavaFX |带示例的上下文菜单

原文:https://www . geesforgeks . org/JavaFX-context menu-with-examples/

ContextMenu 是 JavaFX 库的一部分。ContextMenu 可以与标签、textfield 等控件相关联。右键单击相关控件时，上下文菜单被激活。它显示一个包含几个菜单项或子菜单的弹出窗口。

该类的构造函数为:

上下文菜单():新建一个空的上下文菜单。
上下文菜单(MenuItem… i) :创建包含 MenuItem 的上下文菜单。

常用方法:

方法	说明
【getitem()	返回上下文菜单的项目
getnations()	返回操作属性的值
隐藏()	隐藏上下文菜单
设置动作(事件处理程序 v)	设置“动作”属性的值
显示(节点 a，双 X，双 Y)	在屏幕的指定位置显示上下文菜单

以下程序说明了上下文菜单的使用:

Program to create a context menu and add it to label: A ContextMenu will be created by name ‘contextMenu’ and 3 menuitems: menuItem1, menuItem2, menuItem3 will be added to the menu contextMenu and the menu contextMenu will be associated with a label ‘label’. The label will be created inside a scene, which in turn will be hosted inside a stage. The function setTitle() is used to provide title to the stage. Then a VBox is created, on which addChildren() method is called to attach the menubar inside the scene. Finally, the show() method is called to display the final results.

```java // Program to create a context menu and add it to label import javafx.application.Application; import javafx.scene.Scene; import javafx.scene.control.; import javafx.scene.layout.; import javafx.event.ActionEvent; import javafx.event.EventHandler; import javafx.collections.; import javafx.stage.Stage; import javafx.scene.text.Text.; import javafx.scene.paint.; import javafx.scene.text.; public class contextMenu_1 extends Application {     // labels     Label l;

// launch the application     public void start(Stage stage)     {         // set title for the stage         stage.setTitle("creating contextMenu ");

// create a label         Label label1 = new Label("This is a ContextMenu example ");

// create a menu         ContextMenu contextMenu = new ContextMenu();

// create menuitems         MenuItem menuItem1 = new MenuItem("menu item 1");         MenuItem menuItem2 = new MenuItem("menu item 2");         MenuItem menuItem3 = new MenuItem("menu item 3");

// add menu items to menu         contextMenu.getItems().add(menuItem1);         contextMenu.getItems().add(menuItem2);         contextMenu.getItems().add(menuItem3);

// create a tilepane         TilePane tilePane = new TilePane(label1);

// setContextMenu to label         label1.setContextMenu(contextMenu);

// create a scene         Scene sc = new Scene(tilePane, 200, 200);

// set the scene         stage.setScene(sc);

stage.show();     }

public static void main(String args[])     {         // launch the application         launch(args);     } } ```

输出:
Program to create a context menu and add it to label and associate the context menu with window event listener: A Contextmenu will be created by name contextMenu and 3 menuitems menuItem1, menuItem2, menuItem3 will be added to the menu contextMenu and the contextMenu will be associated with a label l. The label will be created inside a scene, which in turn will be hosted inside a stage. The function setTitle() is used to provide title to the stage. Then a VBox is created, on which addChildren() method is called to attach the menubar inside the scene. Finally, the show() method is called to display the final results. A Window event will be created that will handle the window events of the context menu and will display the state of the context menu by a Label ‘label’. The window event will be associated with the label using setOnHiding() and setOnShowing() functions.

```java // Program to create a context menu and add it to label // and associate the context menu with window event listener import javafx.application.Application; import javafx.scene.Scene; import javafx.scene.control.; import javafx.scene.layout.; import javafx.stage.WindowEvent; import javafx.event.EventHandler; import javafx.collections.; import javafx.stage.Stage; import javafx.scene.text.Text.; import javafx.scene.paint.; import javafx.scene.text.; public class contextMenu extends Application {     // labels     Label label;

// launch the application     public void start(Stage stage)     {         // set title for the stage         stage.setTitle("creating contextMenu ");

// create a label         Label label1 = new Label("This is a ContextMenu example ");

// create a menu         ContextMenu contextMenu = new ContextMenu();

// create menuitems         MenuItem menuItem1 = new MenuItem("menu item 1");         MenuItem menuItem2 = new MenuItem("menu item 2");         MenuItem menuItem3 = new MenuItem("menu item 3");

// add menu items to menu         contextMenu.getItems().add(menuItem1);         contextMenu.getItems().add(menuItem2);         contextMenu.getItems().add(menuItem3);

// label to display events         Label label = new Label("context menu hidden");

// create window event         EventHandler event = new EventHandler() {             public void handle(WindowEvent e)             {                 if (contextMenu.isShowing())                     label.setText("context menu showing");                 else                     label.setText("context menu hidden");             }         };

// add event         contextMenu.setOnShowing(event);         contextMenu.setOnHiding(event);

// create a tilepane         TilePane tilePane = new TilePane(label1);

tilePane.getChildren().add(label);

// setContextMenu to label         label.setContextMenu(contextMenu);

// create a scene         Scene sc = new Scene(tilePane, 200, 200);

// set the scene         stage.setScene(sc);

stage.show();     }

public static void main(String args[])     {         // launch the application         launch(args);     } } ```

输出: