java - 处理 JavaFX 事件，例如从文本字段控件捕获文本

Question

我正在尝试为捕获在 TextField 和 PasswordField 控件中输入的文本的按钮创建一个事件。我知道它与事件处理有关，但不知道如何实现它。您将在我的代码中看到我开始使用的名为 AddHandler 的类。我还尝试构建一个字符串，该字符串将问候并包含用户，并在标记为空的新标签中传递问候标签控件( Pane 的位置 4)。

import javafx.application.Application;
import javafx.geometry.HPos;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.text.Text;
import javafx.scene.control.TextField;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;

public class UserAndPass extends Application {
  @Override // Override the start method in the Application class
  public void start(Stage primaryStage) {
    // Create a pane and set its properties
    GridPane pane = new GridPane();
    pane.setAlignment(Pos.CENTER);
    pane.setPadding(new Insets(11.5, 12.5, 13.5, 14.5));
    pane.setHgap(5.5);
    pane.setVgap(5.5);

    // Place nodes in the pane
    pane.add(new Label("Please enter your username and password: "), 0, 0);
    pane.add(new Label("Username: "), 0, 1);
    pane.add(new TextField(), 1, 1);
    pane.add(new Label("Password: "), 0, 2); 
    pane.add(new TextField(), 1, 2);
    Button btAdd = new Button("Enter");
    pane.add(btAdd, 1, 3);
    // Create and register the handler
    btAdd.setOnAction(new AddHandler());
    GridPane.setHalignment(btAdd, HPos.RIGHT);
    pane.add(new Label(""), 0, 4);

    // Create a scene and place it in the stage
    Scene scene = new Scene(pane);
    primaryStage.setTitle("Login Display"); // Set the stage title
    primaryStage.setScene(scene); // Place the scene in the stage
    primaryStage.show(); // Display the stage
  }

  class AddHandler implements EventHandler<ActionEvent> {
      @Override // Override the handle method
      public void handle(ActionEvent e) {
          AddHandler.enter();
      }
  }

  /**
   * The main method is only needed for the IDE with limited
   * JavaFX support. Not needed for running from the command line.
   */
  public static void main(String[] args) {
    launch(args);
  }
} 

Answer 1

要从处理程序访问文本字段和标签，请将它们设为字段。

public class InnerClasssTest extends Application {

    private TextField usernameField = new TextField();
    private TextField passwordField = new TextField();
    private Label greetingLabel = new Label("");

<小时/>

    pane.add(new Label("Please enter your username and password: "), 0, 0);
    pane.add(new Label("Username: "), 0, 1);
    pane.add(usernameField, 1, 1);
    pane.add(new Label("Password: "), 0, 2);
    pane.add(passwordField, 1, 2);
    Button btAdd = new Button("Enter");
    pane.add(btAdd, 1, 3);
    // Create and register the handler
    btAdd.setOnAction(new AddHandler());
    GridPane.setHalignment(btAdd, HPos.RIGHT);
    pane.add(greetingLabel, 0, 4);

<小时/>

class AddHandler implements EventHandler<ActionEvent> {
    @Override // Override the handle method
    public void handle(ActionEvent e) {
        greetingLabel.setText(String.format(
                "Hello %s@%s.", usernameField.getText(), passwordField.getText()));
    }
}