how to work with Textfield in javafx (scene builder)

[M0TRIX]

hello

i have some textfield in my stage. so i want to get values from textfilds.will u help me plz?

 public class FXMLBookController implements Initializable {

@FXML
public void txt(){


}

@Override
public void initialize(URL url, ResourceBundle rb) {
// TODO
}

}

my Fxml File ::

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

<?import javafx.scene.text.*?>
<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>


<AnchorPane id="AnchorPane" prefHeight="512.0" prefWidth="600.0" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/8" fx:controller="javafxtest.FXMLBookController">
<children>
<Button layoutX="191.0" layoutY="446.0" mnemonicParsing="false" prefHeight="31.0" prefWidth="133.0" text="ثبت">
<font>
<Font name="2 Elham" size="24.0" />
</font>
</Button>
<TextField layoutX="146.0" layoutY="49.0" />
<Label layoutX="458.0" layoutY="51.0" prefHeight="21.0" prefWidth="110.0" text=": کد بین المللی">
<font>
<Font name="2 Elham" size="21.0" />
</font>
</Label>
<Label layoutX="513.0" layoutY="135.0" text=": عنوان">
<font>
<Font name="2 Elham" size="21.0" />
</font>
</Label>
<Label layoutX="495.0" layoutY="209.0" text=": نویسنده">
<font>
<Font name="2 Elham" size="21.0" />
</font>
</Label>
<Label layoutX="513.0" layoutY="285.0" text=": قیمت">
<font>
<Font name="2 Elham" size="21.0" />
</font>
</Label>
<Label layoutX="515.0" layoutY="356.0" text=": گروه">
<font>
<Font name="2 Elham" size="21.0" />
</font>
</Label>
<TextField fx:id="txtfiled" layoutX="146.0" layoutY="131.0" />
<TextField layoutX="146.0" layoutY="207.0" />
<TextField layoutX="146.0" layoutY="281.0" />
<TextField layoutX="146.0" layoutY="354.0" />
</children>
</AnchorPane>