为什么 JavaFX TextField 侦听器不起作用？

Question

我想在我按下前一个窗口上的按钮时出现的窗口中的文本字段中添加一个侦听器。问题是监听器根本不起作用。它没有检测到任何变化。

public class WindowTwoController {

private Stage stage;

@FXML
private TextField imieTF = new TextField();


public void show() throws IOException {

    FXMLLoader loader = new FXMLLoader(getClass().getResource("winTwo.fxml"));
    Parent root = loader.load();

    stage = new Stage();
    stage.initModality(Modality.APPLICATION_MODAL);

    stage.setTitle("Sell Art");
    stage.setScene(new Scene(root, 500, 500));

    imieTF.textProperty().addListener((observable, oldValue, newValue) -> {
        System.out.println("textfield changed from " + oldValue + " to " + newValue);
    });

    stage.showAndWait();

}

我正在更改 textField 的值，但没有任何内容打印到控制台。当在前一个窗口上按下按钮时调用 show 方法。请帮我。这是我的 winTwo.fxml：

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.geometry.Insets?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.ComboBox?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.Separator?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.ColumnConstraints?>
<?import javafx.scene.layout.GridPane?>
<?import javafx.scene.layout.RowConstraints?>
<?import javafx.scene.layout.VBox?>
<?import javafx.scene.text.Font?>

<GridPane alignment="center" hgap="10" prefHeight="441.0" prefWidth="500.0" vgap="10" xmlns="http://javafx.com/javafx/8.0.172-ea" xmlns:fx="http://javafx.com/fxml/1" fx:controller="windowTwo.WindowTwoController">
<columnConstraints>
    <ColumnConstraints />
</columnConstraints>
<rowConstraints>
    <RowConstraints />
</rowConstraints>
<children>
    <VBox prefHeight="354.0" prefWidth="455.0">
        <children>
            <Label alignment="CENTER" prefHeight="45.0" prefWidth="457.0" text="Sprzedaż dzieła">
                <font>
                    <Font size="30.0" />
                </font>
            </Label>
            <Separator prefWidth="200.0" />
            <GridPane prefHeight="139.0" prefWidth="455.0">
                <columnConstraints>
                    <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
                    <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
                </columnConstraints>
                <rowConstraints>
                    <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
                    <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
                </rowConstraints>
                <children>
                    <Label alignment="CENTER" prefHeight="40.0" prefWidth="220.0" text="Imię">
                        <font>
                            <Font size="28.0" />
                        </font>
                    </Label>
                    <Label alignment="CENTER" prefHeight="40.0" prefWidth="220.0" text="Nazwisko" GridPane.rowIndex="1">
                        <font>
                            <Font size="28.0" />
                        </font>
                    </Label>
                    <TextField fx:id="imieTF" GridPane.columnIndex="1">
                        <GridPane.margin>
                            <Insets right="20.0" />
                        </GridPane.margin></TextField>
                    <TextField fx:id="nazwiskoTF" GridPane.columnIndex="1" GridPane.rowIndex="1">
                        <GridPane.margin>
                            <Insets right="20.0" />
                        </GridPane.margin>
                    </TextField>
                </children>
            </GridPane>
            <Separator prefWidth="200.0" />
            <Label alignment="CENTER" prefHeight="17.0" prefWidth="450.0" text="Klient powracający">
                <font>
                    <Font size="22.0" />
                </font>
            </Label>
            <Separator prefWidth="200.0" />
            <GridPane prefHeight="126.0" prefWidth="455.0">
                <columnConstraints>
                    <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
                    <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
                </columnConstraints>
                <rowConstraints>
                    <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
                    <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
                </rowConstraints>
                <children>
                    <Label alignment="CENTER" prefHeight="40.0" prefWidth="220.0" text="Poziom Zaprzyjaźnienia" textFill="#00000080">
                        <font>
                            <Font size="19.0" />
                        </font>
                    </Label>
                    <ComboBox fx:id="cb" opacity="0.5" prefHeight="25.0" prefWidth="207.0" GridPane.columnIndex="1" />
                    <Button mnemonicParsing="false" prefHeight="25.0" prefWidth="175.0" text="Akceptuj" GridPane.rowIndex="1">
                        <GridPane.margin>
                            <Insets left="25.0" />
                        </GridPane.margin>
                    </Button>
                    <Button mnemonicParsing="false" prefHeight="25.0" prefWidth="175.0" text="Anuluj" GridPane.columnIndex="1" GridPane.rowIndex="1">
                        <GridPane.margin>
                            <Insets left="27.0" />
                        </GridPane.margin>
                    </Button>
                </children>
            </GridPane>
        </children>
    </VBox>
</children>
</GridPane>

Answer 1

您应该像这样向私有成员 imieTF 添加注释

public class WindowTwoController {
  @FXML
  private TextField imieTF;

  @FXML
  private void initialize() {
      imieTF.textProperty().addListener((observable, oldValue, newValue) -> 
       {
         System.out.println("textfield changed from " + oldValue + " to " + newValue);
       });
  }

  public static void show() {
    FXMLLoader loader = new FXMLLoader(getClass().getResource("winTwo.fxml"));
    Parent root = loader.load();

    stage = new Stage();
    stage.initModality(Modality.APPLICATION_MODAL);

    stage.setTitle("Sell Art");
    stage.setScene(new Scene(root, 500, 500));
    stage.showAndWait();
  }
}

这应该将 TextField 实例绑定到控制器。但据我所知，当创建属于 fxml 文件的窗口时，FXML 将创建一个新的 WindowTwoController 实例。

另请参阅https://www.callicoder.com/javafx-fxml-form-gui-tutorial/，了解有关其工作原理的基本示例。

请注意，文本字段的所有操作都应该是 JavaFX 流程的一部分，并且不能在 WindowTwoController 的手动实例中完成。请记住，JavaFX 将在 loader.load(); 操作期间创建它自己的 WindowTwoController 实例。