java - 带数据验证的文本框

Question

我想询问用户的性别。我想创建一个文本框，他们可以在其中回答问题。do-while 循环是为了确保他们回答“男孩”或“女孩”。没有错误，但不会运行。

注意我有所有必要的导入...

public class Culminating_JavaFX extends Application {

    String gender; 

    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

    @Override
    public void start(Stage primaryStage) throws Exception {

        GridPane grid = new GridPane();
        TextField textField = new TextField ();

        do
        {
            textField.setPromptText("Are you a boy or a girl?");
            textField.setText("");
            gender = br.readLine().toLowerCase();
        } 
        while (!(gender.equals("boy")) && !(gender.equals("girl")));

        GridPane.setConstraints(textField, 0, 1);
        grid.getChildren().add(textField);

    }

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

}

Answer 1

public class Culminating_JavaFX extends Application {

private GridPane grid = new GridPane();
private TextField textField = new TextField();
private Label label = new Label("Are you boy or girl?");
private Button btn;

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

@Override
public void start(Stage primaryStage) {
    btn = new Button();
    btn.setText("Answer");

    // set action listener -> runs when button is pressed
    btn.setOnAction(new EventHandler<ActionEvent>() {

        @Override
        public void handle(ActionEvent event) {
            // process the form
            process();
        }
    });

    // set constraints
    GridPane.setConstraints(textField, 0, 0);
    GridPane.setConstraints(label, 0, 1);
    GridPane.setConstraints(btn, 0, 2);

    // add components to grid
    grid.getChildren().add(textField);
    grid.getChildren().add(label);
    grid.getChildren().add(btn);

    // show scene
    primaryStage.setScene(new Scene(grid, 300, 250));
    primaryStage.show();
}

private void process() {
    // get text
    String text = textField.getText();

    // process text
    if (text.equals("boy")) {
        label.setText("You are a boy.");
    } else if (text.equals("girl")) {
        label.setText("You are a girl.");
    }
}}

image of required imports

我写了一个简短的例子，请在上面查看。您的程序进入 do-while 循环并停留在那里。它永远不会到达绘制窗口和组件的地步。这就是它不运行的原因。