title: I couldn't change Label text in JavaFX application
body: <p>I want to change the text of a label via <code>setText</code> method but I'm unable to do so, even after defining <code>fx:id</code> parameter.</p>
  
  <p><strong>Welcome.fxml</strong></p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  
  &lt;?import javafx.scene.control.Button?&gt;
  &lt;?import javafx.scene.control.Label?&gt;
  &lt;?import javafx.scene.control.PasswordField?&gt;
  &lt;?import javafx.scene.control.TextField?&gt;
  &lt;?import javafx.scene.image.Image?&gt;
  &lt;?import javafx.scene.image.ImageView?&gt;
  &lt;?import javafx.scene.layout.AnchorPane?&gt;
  &lt;?import javafx.scene.layout.ColumnConstraints?&gt;
  &lt;?import javafx.scene.layout.GridPane?&gt;
  &lt;?import javafx.scene.layout.RowConstraints?&gt;
  &lt;?import javafx.scene.text.Font?&gt;
  
  &lt;AnchorPane id="AnchorPane" prefHeight="247.0" prefWidth="615.0" xmlns="http://javafx.com/javafx/8.0.111" xmlns:fx="http://javafx.com/fxml/1" fx:controller="banking.manager.WelcomeController"&gt;
      &lt;children&gt;
          &lt;Label fx:id="welcomeLabel" layoutX="26.0" layoutY="23.0" prefHeight="29.0" prefWidth="224.0" text="Banking Manager"&gt;
           &lt;font&gt;
              &lt;Font size="24.0" /&gt;
           &lt;/font&gt;&lt;/Label&gt;
          &lt;Button fx:id="exitButton" layoutX="526.0" layoutY="192.0" mnemonicParsing="false" onAction="#handleCloseRequest" prefHeight="27.0" prefWidth="75.0" text="Close" /&gt;
        &lt;Button fx:id="signButton" layoutX="440.0" layoutY="192.0" mnemonicParsing="false" onAction="#handleSignInRequest" prefHeight="27.0" prefWidth="75.0" text="Sign In" /&gt;
        &lt;GridPane layoutX="26.0" layoutY="81.0" prefHeight="79.0" prefWidth="353.0"&gt;
          &lt;columnConstraints&gt;
            &lt;ColumnConstraints hgrow="SOMETIMES" maxWidth="138.0" minWidth="10.0" prefWidth="110.0" /&gt;
            &lt;ColumnConstraints hgrow="SOMETIMES" maxWidth="243.0" minWidth="10.0" prefWidth="243.0" /&gt;
          &lt;/columnConstraints&gt;
          &lt;rowConstraints&gt;
            &lt;RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" /&gt;
            &lt;RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" /&gt;
          &lt;/rowConstraints&gt;
           &lt;children&gt;
              &lt;Label prefHeight="18.0" prefWidth="93.0" text="Username:" GridPane.halignment="CENTER" GridPane.valignment="CENTER"&gt;
                 &lt;font&gt;
                    &lt;Font size="14.0" /&gt;
                 &lt;/font&gt;
              &lt;/Label&gt;
              &lt;Label prefHeight="18.0" prefWidth="93.0" text="Password:" GridPane.halignment="CENTER" GridPane.rowIndex="1" GridPane.valignment="CENTER"&gt;
                 &lt;font&gt;
                    &lt;Font size="14.0" /&gt;
                 &lt;/font&gt;
              &lt;/Label&gt;
              &lt;TextField fx:id="usernameField" prefHeight="27.0" prefWidth="247.0" GridPane.columnIndex="1" /&gt;
              &lt;PasswordField fx:id="passwordField" prefHeight="27.0" prefWidth="251.0" GridPane.columnIndex="1" GridPane.rowIndex="1" /&gt;
           &lt;/children&gt;
        &lt;/GridPane&gt;
        &lt;ImageView fitHeight="117.0" fitWidth="151.0" layoutX="440.0" layoutY="38.0" pickOnBounds="true" preserveRatio="true"&gt;
           &lt;image&gt;
              &lt;Image url="@safebox.png" /&gt;
           &lt;/image&gt;
        &lt;/ImageView&gt;
        &lt;Label fx:id="informationLabel" text="Log in" layoutX="26.0" layoutY="197.0" prefHeight="17.0" prefWidth="353.0" /&gt;
      &lt;/children&gt;
  &lt;/AnchorPane&gt;
  </code></pre>
  
  <p><strong>WelcomeController.java</strong></p>
  
  <pre><code>import java.net.URL;
  import java.sql.ResultSet;
  import java.util.ResourceBundle;
  import javafx.event.ActionEvent;
  import javafx.fxml.FXML;
  import javafx.fxml.FXMLLoader;
  import javafx.fxml.Initializable;
  import javafx.scene.Parent;
  import javafx.scene.Scene;
  import javafx.scene.control.Button;
  import javafx.scene.control.PasswordField;
  import javafx.scene.control.TextField;
  import javafx.stage.Stage;
  
  import javafx.scene.control.Alert;
  import javafx.scene.control.Alert.AlertType;
  import javafx.scene.control.Label;
  
  /**
   *
   * @author apple
   */
  public class WelcomeController implements Initializable {
  
      @FXML
      private Button signButton;
      private Button exitButton;
      private Label informationLabel = new Label();
      private TextField usernameField = new TextField();
      private PasswordField passwordField = new PasswordField();
  
      @FXML
      private void handleSignInRequest(ActionEvent event) throws Exception {
  
          informationLabel.setText("Please wait while request is getting processed...");
          // ...
  </code></pre>
  
  <p>I tried to move it in another event handler, but still nothing.</p>