title: NullPointerException in JavaFX controller
body: <p>My project is really simple atm. It has two TextFields named <code>latField</code> and <code>longField</code>. All I'm trying to do is print the string values contained in these fields using the <code>getText()</code> method, and occasionally set them using the <code>setText()</code> method. </p>
  
  <p>Note that I'm using javafx scene builder, and there is a <code>FXMLDocument</code> and <code>FXMLDocumentController</code></p>
  
  <p><strong>FXMLDocument.fxml</strong></p>
  
  <pre class="lang-fxml prettyprint-override"><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  
  &lt;?import java.lang.*?&gt;
  &lt;?import java.util.*?&gt;
  &lt;?import javafx.scene.*?&gt;
  &lt;?import javafx.scene.control.*?&gt;
  &lt;?import javafx.scene.layout.*?&gt;
  
  &lt;AnchorPane id="AnchorPane" prefHeight="200" prefWidth="320" style="-fx-background-color: #eee;" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="pokemongocontroller.FXMLDocumentController"&gt;
      &lt;children&gt;
          &lt;Label fx:id="label" layoutX="114.0" layoutY="92.0" minHeight="16" minWidth="69" /&gt;
          &lt;Button id="upButton" layoutX="140.0" layoutY="84.0" mnemonicParsing="false" onAction="#upButtonClick" prefHeight="36.0" prefWidth="38.0" text="U" /&gt;
          &lt;Button id="downButton" layoutX="140.0" layoutY="140.0" mnemonicParsing="false" onAction="#downButtonClick" prefHeight="36.0" prefWidth="38.0" text="D" /&gt;
          &lt;Button id="leftButton" layoutX="94.0" layoutY="106.0" mnemonicParsing="false" onAction="#leftButtonClick" prefHeight="36.0" prefWidth="38.0" text="L" /&gt;
          &lt;Button id="rightButton" layoutX="188.0" layoutY="106.0" mnemonicParsing="false" onAction="#rightButtonClick" prefHeight="36.0" prefWidth="38.0" text="R" /&gt;
          &lt;TextField id="latField" layoutX="25.0" layoutY="27.0" prefHeight="22.0" prefWidth="69.0" text="0.0" /&gt;
          &lt;TextField id="longField" layoutX="98.0" layoutY="27.0" prefHeight="22.0" prefWidth="69.0" text="0.0" /&gt;
          &lt;Label layoutX="47.0" layoutY="49.0" text="Lat" /&gt;
          &lt;Label layoutX="119.0" layoutY="49.0" text="Long" /&gt;
          &lt;Button id="goButton" layoutX="188.0" layoutY="28.0" mnemonicParsing="false" onAction="#goButtonClick" prefHeight="28.0" prefWidth="78.0" text="GO!" /&gt;
        &lt;TextField id="text" layoutX="47.0" layoutY="158.0" prefHeight="22.0" prefWidth="69.0" text="dfgdfg" /&gt;
      &lt;/children&gt;
  &lt;/AnchorPane&gt;
  </code></pre>
  
  <p><strong>FXMLDocumentController.java</strong></p>
  
  <pre><code>public class FXMLDocumentController implements Initializable {
  
      private double delta=0.00001;
      private double latitude,longitude;
  
  
      @FXML
      private  Button upButton,downButton,rightButton,leftButton,goButton;
      private  TextField latField;
      private  TextField longField;
  
      @FXML
      private void upButtonClick(ActionEvent event) {
          System.out.println("You clicked U!");
          latitude+=delta;
          printCoordinates();
  
      }
      @FXML
      private void downButtonClick(ActionEvent event) {
          System.out.println("You clicked D!");
          latitude-=delta;
          printCoordinates();
  
      }
      @FXML
      private void leftButtonClick(ActionEvent event) {
          System.out.println("You clicked L!");
          longitude-=delta;
          printCoordinates();
  
      }
      @FXML
      private void rightButtonClick(ActionEvent event) {
          System.out.println("You clicked R!");
          longitude+=delta;
          printCoordinates();
  
      }
       @FXML
      private void goButtonClick(ActionEvent event) {
          System.out.println("You clicked Go!");
          latitude= Double.parseDouble(latField.getText());
          longitude= Double.parseDouble(longField.getText());
          printCoordinates();
          System.out.println(text.getText());
  
      }
  
      @Override
      public void initialize(URL url, ResourceBundle rb) {
          latField.setText("0.0");
          longField.setText("0.0");
          latitude= Double.parseDouble(latField.getText());
          longitude= Double.parseDouble(longField.getText());
          printCoordinates();
          System.out.println(text.getText());
  
      }    
  
      private void printCoordinates(){
           System.out.println("Latitude: "+latitude);
           System.out.println("Longitude: "+longitude);
      }
  
  }
  </code></pre>
  
  <p>I'm getting a Null Pointer Exception in the following line-</p>
  
  <pre><code>latField.setText("0.0");
  </code></pre>
  
  <p><strong>Full Stacktrace-</strong></p>
  
  <pre><code>Exception in Application start method
  java.lang.reflect.InvocationTargetException
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.lang.reflect.Method.invoke(Method.java:497)
      at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
      at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.lang.reflect.Method.invoke(Method.java:497)
      at sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:767)
  Caused by: java.lang.RuntimeException: Exception in Application start method
      at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
      at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$152(LauncherImpl.java:182)
      at com.sun.javafx.application.LauncherImpl$$Lambda$50/1343441044.run(Unknown Source)
      at java.lang.Thread.run(Thread.java:745)
  Caused by: javafx.fxml.LoadException: 
  file:/E:/PokemonGo/PokemonGoController/dist/run583471250/PokemonGoController.jar!/pokemongocontroller/FXMLDocument.fxml
  
      at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2605)
      at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2583)
      at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2445)
      at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3218)
      at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3179)
      at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3152)
      at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3128)
      at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3108)
      at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3101)
      at pokemongocontroller.PokemonGoController.start(PokemonGoController.java:26)
      at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$159(LauncherImpl.java:863)
      at com.sun.javafx.application.LauncherImpl$$Lambda$53/107178178.run(Unknown Source)
      at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$172(PlatformImpl.java:326)
      at com.sun.javafx.application.PlatformImpl$$Lambda$46/355629945.run(Unknown Source)
      at com.sun.javafx.application.PlatformImpl.lambda$null$170(PlatformImpl.java:295)
      at com.sun.javafx.application.PlatformImpl$$Lambda$48/1823905343.run(Unknown Source)
      at java.security.AccessController.doPrivileged(Native Method)
      at com.sun.javafx.application.PlatformImpl.lambda$runLater$171(PlatformImpl.java:294)
      at com.sun.javafx.application.PlatformImpl$$Lambda$47/1915503092.run(Unknown Source)
      at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
      at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
      at com.sun.glass.ui.win.WinApplication.lambda$null$145(WinApplication.java:101)
      at com.sun.glass.ui.win.WinApplication$$Lambda$36/1963387170.run(Unknown Source)
      ... 1 more
  Caused by: java.lang.NullPointerException
      at pokemongocontroller.FXMLDocumentController.initialize(FXMLDocumentController.java:84)
      at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2552)
      ... 22 more
  Exception running application myapplication.ApplicationController
  Java Result: 1
  </code></pre>
  
  <p><strong>Here is my ApplcationController.java</strong></p>
  
  <pre><code>import javafx.application.Application;
  import javafx.event.EventHandler;
  
  import javafx.fxml.FXMLLoader;
  import javafx.scene.Parent;
  import javafx.scene.Scene;
  import javafx.scene.input.KeyEvent;
  import javafx.stage.Stage;
  
  /**
   *
   * @author Lomesh
   */
  public class ApplicationController extends Application {
  
      @Override
      public void start(Stage stage) throws Exception {
          Parent root = FXMLLoader.load(getClass().getResource("FXMLDocument.fxml"));       
          Scene scene = new Scene(root);
          stage.setScene(scene);
          stage.show();
      }
  
      /**
       * @param args the command line arguments
       */
      public static void main(String[] args) {
          launch(args);
      }
  
  }
  </code></pre>
  
  <p>What I understand is that the controls defined in FXML are not getting injected into the FXMLDocumentController.java but don't know why. <strong>WHY?</strong></p>