JavaFX TabPane:如何监听选择更改

Question

当用户从一个选项卡转到另一个选项卡时,我想做一些操作,因为我使用Scene Builder进行了表单设计我不能使用这里提到的代码(他使用了TabPaneBuilder类)

我猜这个代码可以工作,但它不会对选项卡选择更改做出反应.

@FXML
protected TabPane chatTabs;
.
.    
.
chatTabs.selectionModelProperty().addListener(
    new ChangeListener<SingleSelectionModel<Tab>> {
            @Override
            public void changed(ObservableValue<? extends SingleSelectionModel<Tab>> ov, SingleSelectionModel<Tab> t, SingleSelectionModel<Tab> t1) {
                System.err.println("changed");
            }
        }
    }
);

Answer 1

使用更改侦听器的正确方法是:

chatTabs.getSelectionModel().selectedItemProperty().addListener(
    new ChangeListener<Tab>() {
        @Override
        public void changed(ObservableValue<? extends Tab> ov, Tab t, Tab t1) {
            System.out.println("Tab Selection changed");
        }
    }
);

Why code in question didn't work? I guess its because your change listener listens to changes in "selectionModel" instead of "selectedItem"

Finding out when a tab has been added or removed is a little trickier:

tabs.addListener( (Change<? extends Tab> change) -> {
  while( change.next() ) {
    if( change.wasAdded() ) {
      for( final Tab tab : change.getAddedSubList() ) {
        System.out.println( "Tab Added: " + tab );
      }
    } else if( change.wasRemoved() ) {
      // ...
    }
  }
} );

Answer 2

或者在Java 8中使用lambda表达式....

chatTabs.getSelectionModel().selectedItemProperty().addListener((ov, oldTab, newTab) -> {
        System.err.println("changed");
    });

Answer 3

我认为更好、更自然的方法是使用 Tab.setOnSelectionChanged。这是一个实现该方法的完整小程序。您可以在这里看到更完整的示例： http: //sandsduchon.org/duchon/cs335/fx020.html

请注意，您还应该使用 Tab.isSelected 对选择此选项卡或取消选择此选项卡做出正确反应。

import javafx.application.Application; // FX base, requires start(Stage)
import javafx.stage.Stage;             // required by start (Stage)
import javafx.scene.Scene;             // no scene --> no display

import javafx.scene.control.TabPane;
import javafx.scene.control.Tab;

public class TabDemo extends Application {

   public void start (Stage stage) {
      TabPane tabPane = new TabPane ();

      Tab tba = new Tab ("one");
      Tab tbb = new Tab ("two");

      tabPane.getTabs().addAll (tba, tbb);

      tba.setOnSelectionChanged (e -> 
        System.out.println (
           tba.isSelected()?
           "a selected":
           "a unselected"
        )
      );

      Scene scene = new Scene (tabPane, 200, 50);
      stage.setScene (scene);
      stage.setTitle ("A Study of tab listeners");
      stage.show ();
   } // end start

} // end class TabDemo