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JavaFX : TextField always outputs "", so function gives NumberFormatException and others

I wanted to do a test drive on JavaFx, and tried to create an app that can divide two values, but whenever i run it, it gives TextField output to be "".
Here's my code:
package com.example.javafxprojecttest;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;
import static java.lang.System.*;
public class Divide extends Application {
#Override
public void start(Stage stage) throws Exception {
stage.setTitle("Divide values");
Label divisionVal1 = new Label("Dividend : ");
TextField dividend = new TextField();
TextField divisor = new TextField();
Label divisionVal2 = new Label("Divisor : ");
Button divide = new Button("Divide");
String dividendString = dividend.getText();
String divisorString = divisor.getText();
double d = Double.parseDouble(dividendString) / Double.parseDouble(divisorString);
divide.setOnAction(e -> {
out.println(d);
}
);
GridPane root = new GridPane();
root.addRow(0, divisionVal1, dividend);
root.addRow(1, divisionVal2, divisor);
root.addRow(2, divide);
Scene scene = new Scene(root, 400, 400);
stage.setScene(scene);
stage.show();
}
public static void main(String[] args) {
launch();
}
}
Output :
Exception in Application start method
java.lang.reflect.InvocationTargetException
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:465)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:364)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at java.base/sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:1071)
Caused by: java.lang.RuntimeException: Exception in Application start method
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:901)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:196)
at java.base/java.lang.Thread.run(Thread.java:833)
Caused by: java.lang.NumberFormatException: empty String
at java.base/jdk.internal.math.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1842)
at java.base/jdk.internal.math.FloatingDecimal.parseDouble(FloatingDecimal.java:110)
at java.base/java.lang.Double.parseDouble(Double.java:651)
at com.example.javafxprojecttest/com.example.javafxprojecttest.Add.start(Add.java:24)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:847)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:484)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:457)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:456)
at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:184)
... 1 more
Exception running application com.example.javafxprojecttest.Add
Process finished with exit code 1
I dont know how to fix this nor do I know wht I have to add with this question for you to be able to answer it.
I tried to look at a lot of other questions here on StackOverflow but found none to be useful to me, and I am also rather new to StackOverflow(asking questions), so I dont know much on documenting the error.

Well i got it myself by just transferring all that to inside the button action.
public void start(Stage stage) throws Exception {
stage.setTitle("Divide values");
Label divisionVal1 = new Label("Dividend : ");
TextField dividend = new TextField();
TextField divisor = new TextField();
Label divisionVal2 = new Label("Divisor : ");
Button divide = new Button("Divide");
divide.setOnAction(e -> {
String dividendString = dividend.getText();
String divisorString = divisor.getText();
double d = Double.parseDouble(dividendString) / Double.parseDouble(divisorString);
out.println(d);
}
);

Error while trying to add a button using JavaFX

I have a problem while trying to add a button on an HBox. The error that I got is "Cannot invoke "javafx.scene.layout.HBox.getChildren()" because "this.buttonBox" is null" even though I already have an HBox with fx:id buttonBox. Can someone help me with this?
And I also tried to add a new HBox on the code and then add a button but the button did not show up.
Here is my code:
package com.example.simplemaps;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.fxml.FXML;
import javafx.geometry.Insets;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.layout.HBox;
import java.io.IOException;
import java.util.ArrayList;
public class View {
public static final String INTERFACE_LOCATION = "maps-view.fxml";
private static final Image IMG_BACKGROUND = new Image("com/example/simplemaps/AisleForward.jpg");
private static final Image IMG_FOREGROUND = new Image("com/example/simplemaps/Bunny.png");
//private Controller controller;
#FXML private Label label;
#FXML private ImageView imageBackground;
#FXML private ImageView imageForeground;
#FXML private HBox buttonBox;
public View() {
//controller = new Controller();
}
public void pickUp()
{
// TO DO
}
public void putDown()
{
imageForeground.setImage(IMG_FOREGROUND);
}
public void start()
{
try
{
FXMLLoader fxmlLoader = new FXMLLoader(SimpleMaps.class.getResource(INTERFACE_LOCATION));
Parent anchorPane = fxmlLoader.load();
SimpleMaps.mainStage.setScene(new Scene(anchorPane));
SimpleMaps.mainStage.show();
}
catch(IOException e)
{
e.printStackTrace();
System.exit(1);
}
}
public void addWhereToButtons(String exit) {
//for(String exit : exits) {
Button button = new Button(exit);
HBox.setMargin(button, new Insets(10.0,0.0,10.0,5.0));
buttonBox.getChildren().add(button);
button.setOnAction(new EventHandler<ActionEvent>() {
#Override public void handle(ActionEvent e) {
//controller.selectExitDirection(exit);
}
}
);
//}
}
}
This is the error:
/Library/Java/JavaVirtualMachines/openjdk.jdk/Contents/Home/bin/java --module-path /Users/ulfianidian/Desktop/IPPO/javafx-sdk-17.0.0.1/lib --add-modules javafx.controls,javafx.fxml -Djava.library.path=/Users/ulfianidian/Desktop/IPPO/javafx-sdk-17.0.0.1/lib -javaagent:/Applications/IntelliJ IDEA CE.app/Contents/lib/idea_rt.jar=51875:/Applications/IntelliJ IDEA CE.app/Contents/bin -Dfile.encoding=UTF-8 -classpath /Users/ulfianidian/Desktop/IPPO/SimpleMaps/target/classes:/Users/ulfianidian/Desktop/IPPO/javafx-sdk-17.0.0.1/lib/javafx-swt.jar:/Users/ulfianidian/Desktop/IPPO/javafx-sdk-17.0.0.1/lib/javafx.web.jar:/Users/ulfianidian/Desktop/IPPO/javafx-sdk-17.0.0.1/lib/javafx.base.jar:/Users/ulfianidian/Desktop/IPPO/javafx-sdk-17.0.0.1/lib/javafx.fxml.jar:/Users/ulfianidian/Desktop/IPPO/javafx-sdk-17.0.0.1/lib/javafx.media.jar:/Users/ulfianidian/Desktop/IPPO/javafx-sdk-17.0.0.1/lib/javafx.swing.jar:/Users/ulfianidian/Desktop/IPPO/javafx-sdk-17.0.0.1/lib/javafx.controls.jar:/Users/ulfianidian/Desktop/IPPO/javafx-sdk-17.0.0.1/lib/javafx.graphics.jar com.example.simplemaps.SimpleMaps
Exception in Application start method
java.lang.reflect.InvocationTargetException
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:465)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:364)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at java.base/sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:1071)
Caused by: java.lang.RuntimeException: Exception in Application start method
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:901)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:196)
at java.base/java.lang.Thread.run(Thread.java:833)
Caused by: java.lang.NullPointerException: Cannot invoke "javafx.scene.layout.HBox.getChildren()" because "this.buttonBox" is null
at com.example.simplemaps.View.addWhereToButtons(View.java:66)
at com.example.simplemaps.Controller.start(Controller.java:21)
at com.example.simplemaps.SimpleMaps.start(SimpleMaps.java:20)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:847)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:484)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:457)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:456)
at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
Exception running application com.example.simplemaps.SimpleMaps
Process finished with exit code 1

You need to cast a new HBox to buttonBox, as such.
HBox buttonBox = new HBox();

NPE when trying to get text from a textfield?

So my plan is to get the text from the textfield to save it in the "currentvalue" variable and make it save a new value every time one of the methods is called from the buttons.
This is my Controller Class:
package application;
import java.io.IOException;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import javafx.stage.Stage;
public class Controller {
#FXML
Button buttonyes,buttonno;
private Stage stage;
private Scene scene;
private Parent root;
public void yes(ActionEvent event) throws IOException {
root = FXMLLoader.load(getClass().getResource("Order.fxml"));
stage = (Stage)((Node)event.getSource()).getScene().getWindow();
scene = new Scene(root);
stage.setScene(scene);
stage.show();
}
public void no(ActionEvent event) {
System.exit(0);
}
#FXML
Button buttonback;
public void back(ActionEvent event) throws IOException{
root = FXMLLoader.load(getClass().getResource("Welcome.fxml"));
stage = (Stage)((Node)event.getSource()).getScene().getWindow();
scene = new Scene(root);
stage.setScene(scene);
stage.show();
}
#FXML
private TextField display = new TextField("0,00"); // I either get a NFE here
double currentvalue = Double.parseDouble(display.getText()); //or a NPE here if I delete the new TextField line
double value1 = 3.00;
double value2 = 2.50;
double value3 = 2.00;
double value4 = 1.50;
double value5 = 1.00;
public void order3() {
display.setText(String.valueOf(currentvalue+value1));
}
public void order25() {
display.setText(String.valueOf(currentvalue+value2));
}
public void order2() {
display.setText(String.valueOf(currentvalue+value3));
}
public void order15() {
display.setText(String.valueOf(currentvalue+value4));
}
public void order1() {
display.setText(String.valueOf(currentvalue+value5));
}
public void order(ActionEvent event) throws IOException{
root = FXMLLoader.load(getClass().getResource("Bye.fxml"));
stage = (Stage)((Node)event.getSource()).getScene().getWindow();
scene = new Scene(root);
stage.setScene(scene);
stage.show();
}
}
So basically I'm trying to calculate a new value to show in the text field once a button is pressed. I've tried a lot of solutions I found online but nothing seems to work that's why I'm asking here.
Here's the error for the NFE
javafx.fxml.LoadException:
/C:/Users/daydr/eclipse-workspace/Projektarbeit-Bestellen/Bestellservice/bin/application/Welcome.fxml:11
at javafx.fxml/javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2707)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2685)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2548)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3323)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3280)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3249)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3222)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3199)
at javafx.fxml/javafx.fxml.FXMLLoader.load(FXMLLoader.java:3192)
at application.Main.start(Main.java:14)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:846)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:474)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:447)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:446)
at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:174)
at java.base/java.lang.Thread.run(Thread.java:832)
Caused by: java.lang.NumberFormatException: For input string: "0,00"
at java.base/jdk.internal.math.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:2054)
at java.base/jdk.internal.math.FloatingDecimal.parseDouble(FloatingDecimal.java:110)
at java.base/java.lang.Double.parseDouble(Double.java:549)
at application.Controller.<init>(Controller.java:52)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:64)
at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:500)
at java.base/java.lang.reflect.ReflectAccess.newInstance(ReflectAccess.java:128)
at java.base/jdk.internal.reflect.ReflectionFactory.newInstance(ReflectionFactory.java:350)
at java.base/java.lang.Class.newInstance(Class.java:645)
at javafx.fxml/javafx.fxml.FXMLLoader$ValueElement.processAttribute(FXMLLoader.java:938)
at javafx.fxml/javafx.fxml.FXMLLoader$InstanceDeclarationElement.processAttribute(FXMLLoader.java:982)
at javafx.fxml/javafx.fxml.FXMLLoader$Element.processStartElement(FXMLLoader.java:229)
at javafx.fxml/javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:754)
at javafx.fxml/javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2808)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2634)
... 17 more
and the one for the NPE
javafx.fxml.LoadException:
/C:/Users/daydr/eclipse-workspace/Projektarbeit-Bestellen/Bestellservice/bin/application/Welcome.fxml:11
at javafx.fxml/javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2707)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2685)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2548)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3323)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3280)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3249)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3222)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3199)
at javafx.fxml/javafx.fxml.FXMLLoader.load(FXMLLoader.java:3192)
at application.Main.start(Main.java:14)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:846)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:474)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:447)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:446)
at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:174)
at java.base/java.lang.Thread.run(Thread.java:832)
Caused by: java.lang.NullPointerException: Cannot invoke "javafx.scene.control.TextField.getText()" because "this.display" is null
at application.Controller.<init>(Controller.java:52)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:64)
at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:500)
at java.base/java.lang.reflect.ReflectAccess.newInstance(ReflectAccess.java:128)
at java.base/jdk.internal.reflect.ReflectionFactory.newInstance(ReflectionFactory.java:350)
at java.base/java.lang.Class.newInstance(Class.java:645)
at javafx.fxml/javafx.fxml.FXMLLoader$ValueElement.processAttribute(FXMLLoader.java:938)
at javafx.fxml/javafx.fxml.FXMLLoader$InstanceDeclarationElement.processAttribute(FXMLLoader.java:982)
at javafx.fxml/javafx.fxml.FXMLLoader$Element.processStartElement(FXMLLoader.java:229)
at javafx.fxml/javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:754)
at javafx.fxml/javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2808)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2634)
... 17 more

Since you haven't included the FXML we can only assume that TextField "display" is in the FXML file. That means it will be created through the FXML loader. Don't assign display to a new TextField.
You can access display in the initialize method.
#Override
public void initialize(){
currentValue = Double.parseDouble(display.getText());
}
You have an issue with locale, so you could calculate the text with a localized parse.
currentValue = NumberFormat.getInstance().parse(display.getText()).doubleValue();
This will use the default locale, which may more may not use a comma.
Finally, you might want to consider binding. Since you're using javafx.
DoubleProperty currentValueProperty = new DoubleProperty();
public void initialize(){
display.textProperty().bindBidirectional​( currentValueProperty, NumberFormat.getInstance() )
}

JavaFX/Netbeans Program Not Running

This is my code that I have so far in my Netbeans program. It is supposed to bring up a window with a picture in it, the picture being called seawave. But for some reason it is not running. Do you have any idea why?
package myseaapp;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.Pane;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;
import javafx.stage.StageStyle;
public class MySeaApp extends Application {
private ImageView seawave;
private Rectangle seawaveClip;
#Override
public void start(Stage primaryStage) {
primaryStage.initStyle(StageStyle.TRANSPARENT);
seawave = new ImageView(new Image(MySeaApp.class.getResourceAsStream("images/seawave")));
seawaveClip = new Rectangle(300, 220);
seawaveClip.setArcHeight(20);
seawaveClip.setArcWidth(20);
seawave.setClip(seawaveClip);
Pane root = new Pane();
root.getChildren().add(seawave);
Scene myScene = new Scene(root, 300, 250);
myScene.setFill(null);
primaryStage.setScene(myScene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
and this is what I get...
Executing /Users/SethRataiczak/NetBeansProjects/MySeaApp/dist/run1104410607/MySeaApp.jar using platform /Library/Java/JavaVirtualMachines/jdk1.8.0_60.jdk/Contents/Home/jre/bin/java
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$156(LauncherImpl.java:182)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException: Input stream must not be null
at javafx.scene.image.Image.validateInputStream(Image.java:1110)
at javafx.scene.image.Image.<init>(Image.java:694)
at myseaapp.MySeaApp.start(MySeaApp.java:30)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$163(LauncherImpl.java:863)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$176(PlatformImpl.java:326)
at com.sun.javafx.application.PlatformImpl.lambda$null$174(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$175(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
Exception running application myseaapp.MySeaApp
Java Result: 1
Deleting directory /Users/SethRataiczak/NetBeansProjects/MySeaApp/dist/run1104410607
jfxsa-run:
BUILD SUCCESSFUL (total time: 1 second)

First of All use try and catch block for error handling like this
try {
// code
}catch {
// error handling code
}
and second you did not use your image type example .png, .jpg etc
seawave = new ImageView(new Image(MySeaApp.class.getResourceAsStream("images/seawave")));
change this line of code with correct image type
Like this:
seawave = new ImageView(new Image(MySeaApp.class.getResourceAsStream("images/seawave.jpg")));

Program doesn't start when I use mediaPlayer

Problem:
everything was working fine until I decided to add the media with the mediaPlayer into the program. The reason I know the mediaPlayer is the culprit is because I set the function that runs the mediaPlayer to the end of the main function and the screen would then appear for second and then vanish as oppose to not running at all if I set the function anywhere else.
Relevant code that is causing the problem
private void playThemeIntro()
{
Media gameIntroTheme = new Media("GameIntroTheme.MP3");
mediaPlayer = new MediaPlayer(gameIntroTheme);
mediaPlayer.setAutoPlay(true);
}
Entire code
package whowantstobeamillionairetriviagame;
import java.io.File;
import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.media.Media;
import javafx.scene.control.Button;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.Background;
import javafx.scene.layout.Priority;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.scene.media.MediaPlayer;
import javafx.scene.paint.Paint;
import javafx.scene.shape.Rectangle;
import javafx.scene.text.Font;
import javafx.scene.text.FontWeight;
import javafx.stage.Stage;
public class WhoWantsToBeAMillionaireTriviaGame extends Application
{
private VBox menuLayout;
private MediaPlayer mediaPlayer;
#Override
public void start(Stage startingStage) throws Exception
{
StackPane backgroundSettings = new StackPane();
Image backgroundColor = new Image("http://1.bp.blogspot.com/-p0s06MBIx_U/T8zKIBZ24pI/AAAAAAAAA7Y/n8hMZfpRic0/s1600/dark+blue+wallpaper+10.jpg");
ImageView background = new ImageView();
background.setImage(backgroundColor);
createMenuLayout();
backgroundSettings.getChildren().addAll(background, menuLayout);
playThemeIntro(); // If you comment this out, the program works properly
Scene backgroundScene = new Scene(backgroundSettings);
startingStage.setScene(backgroundScene);
startingStage.setTitle("Who Wants to be a Millionaire");
startingStage.show();
}
private void playThemeIntro()
{
Media gameIntroTheme = new Media("GameIntroTheme.MP3");
mediaPlayer = new MediaPlayer(gameIntroTheme);
mediaPlayer.setAutoPlay(true);
}
private VBox createMenuLayout()
{
menuLayout = new VBox();
menuLayout.setSpacing(20);
menuLayout.setAlignment(Pos.TOP_CENTER);
Image millionaireLogo = new Image(new File("MillionaireLogo1.PNG").toURI().toString());
ImageView logoPicture = new ImageView();
logoPicture.setImage(millionaireLogo);
logoPicture.setPreserveRatio(true);
logoPicture.setSmooth(true);
logoPicture.setCache(true);
menuLayout.getChildren().add(logoPicture);
Button menuButtons[] = new Button[]
{
new Button("Play"),
new Button("Options"),
new Button("Help"),
new Button("Exit")
};
for (int i = 0; i < 4; i++)
{
menuButtons[i].setPrefSize(200, 30);
Rectangle r = new Rectangle(200, 30, Paint.valueOf("346699"));
r.setArcHeight(30);
r.setArcWidth(30);
menuButtons[i].setOnMouseEntered(e -> r.setFill(Paint.valueOf("0f69b4")));
menuButtons[i].setOnMouseExited(e -> r.setFill(Paint.valueOf("346699")));
menuButtons[i].setBackground(Background.EMPTY);
menuButtons[i].setTextFill(Paint.valueOf("White"));
menuButtons[i].setFont(Font.font("Serif", FontWeight.BOLD, 16));
VBox.setMargin(menuButtons[i], new Insets(0, 0, 0, 8));
VBox.setVgrow(menuButtons[i], Priority.ALWAYS);
StackPane sp = new StackPane();
sp.getChildren().addAll(r, menuButtons[i]);
menuLayout.getChildren().add(sp);
}
return menuLayout;
}
public static void main(String[] args)
{
launch(args);
}
}
Error that I got
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$$Lambda$50/1642360923.run(Unknown Source)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.IllegalArgumentException: uri.getScheme() == null! uri == 'GameIntroTheme.MP3'
at com.sun.media.jfxmedia.locator.Locator.<init>(Locator.java:211)
at javafx.scene.media.Media.<init>(Media.java:391)
at whowantstobeamillionairetriviagame.WhoWantsToBeAMillionaireTriviaGame.playThemeIntro(WhoWantsToBeAMillionaireTriviaGame.java:57)
at whowantstobeamillionairetriviagame.WhoWantsToBeAMillionaireTriviaGame.start(WhoWantsToBeAMillionaireTriviaGame.java:46)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$159(LauncherImpl.java:863)
at com.sun.javafx.application.LauncherImpl$$Lambda$53/792965399.run(Unknown Source)
at com.sun.javafx.application.PlatformImpl.lambda$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$48/266742917.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$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
Exception running application whowantstobeamillionairetriviagame.WhoWantsToBeAMillionaireTriviaGame
Java Result: 1

The Media constructor requires a string that represents a URL with a file:, http:, or jar: scheme.
I don't know your project layout, so I can't give a definitive answer, but you probably need something like
Media gameIntroTheme =
new Media(getClass().getResource("GameIntroTheme.MP3").toExternalForm());

Here is the answer
Media gameIntroTheme = new Media(newFile("GameIntroTheme.MP3").toURI().toString());