用一个按钮javafx以干净的方式进行多项操作

Question

I am wondering if there is a way to use single JavaFX Button and perform different actions on this single Button depending on some another condition (example: perform action one when clicked if option one was chosen, action two when option two etc.) in clean way.

I could make it with if statements, that is obvious, but I would prefer some decent and clean way to do that.

Could you suggest me some ideas in orded to achieve that?

Answer 1

Associate the handler to the option. You could do eg this using a Map<Option, EventHandler<ActionEvent>> or by simply by implementing functionality in the options themself.

The following example lets the user choose between closing printing Hello World to the console or closing the application in a ComboBox :

// handler with a given return value for toString()
public abstract class NamedEventHandler implements EventHandler<ActionEvent> {

    private final String name;

    public NamedEventHandler(String name) {
        this.name = name;
    }

    @Override
    public final String toString() {
        return name;
    }

}

ComboBox<EventHandler<ActionEvent>> comboBox = new ComboBox<>(FXCollections.observableArrayList(
        new NamedEventHandler("Print \"Hello World\"") {
            @Override
            public void handle(ActionEvent event) {
                System.out.println("Hello World");
            }
        }, new NamedEventHandler("Close") {
            @Override
            public void handle(ActionEvent event) {
                Platform.exit();
            }
        }
));

Button button = new Button("OK");
button.setOnAction((ActionEvent event) -> {
    EventHandler<ActionEvent> handler = comboBox.getValue();
    if(handler != null) {
        handler.handle(event);
    }
});

Using a Map map to store the event handlers, you'd use

EventHandler<ActionEvent> handler = map.get(comboBox.getValue());

instead of

EventHandler<ActionEvent> handler = comboBox.getValue();

Answer 2

I think that you could use a map of methods, something like that:

Map<String, Method> actions = new HashMap();

Then, get the methods ready to be called:

Method method1 = classInstance.getClass().getMethod("myMethodOne")
Method method2 = classInstance.getClass().getMethod("myMethodTwo")
...

and populate the map with the methods and their names:

actions.put("methodOne", method1);
actions.put("methodTwo", method2);

So based on the text entered in a TextField (or anything) you could invoke the desired method, something like:

String nameMethodToInvoke = myTextField.getText();
Method methodToInvoke = actions.get(nameMethodToInvoke);
methodToInvoke.invoke()