如果TextField为空，如何禁用按钮？

Question

我无法禁用我的按钮。 “accept”=按钮，“email”= textField。

email.setOnAction(new EventHandler<ActionEvent>() {

    @Override
    public void handle(ActionEvent event) 
    {
        if(email.getText().isEmpty() == false)
        {
            accept.setDisable(false);

        }else accept.setDisable(true);
    }
});

如果我在textField中写，它什么都没有。

Answer 1

你可以使用一个简单的BooleanBinding绑定到Button的disabledProperty。完成此操作只需2行代码：

BooleanBinding isTextFieldEmpty = Bindings.isEmpty(textField.textProperty());
button.disableProperty().bind(isTextFieldEmpty);

您可以使用下面的MCVE查看它的实际效果：

import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.beans.binding.BooleanBinding;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class BooleanBindingExample extends Application {

    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage primaryStage) {

        // Simple interface
        VBox root = new VBox(5);
        root.setPadding(new Insets(10));
        root.setAlignment(Pos.CENTER);

        // TextField and Button
        TextField textField = new TextField();
        Button button = new Button("Click Me");
        root.getChildren().addAll(textField, button);

        // Create a BooleanBinding for the textField to hold whether it is null
        BooleanBinding isTextFieldEmpty = Bindings.isEmpty(textField.textProperty());

        // Now, bind the Button's disableProperty to that BooleanBinding
        button.disableProperty().bind(isTextFieldEmpty);

        // Show the Stage
        primaryStage.setWidth(300);
        primaryStage.setHeight(300);
        primaryStage.setScene(new Scene(root));
        primaryStage.show();
    }
}