I've made a program that generates random courses, with each one having random seminars and students.
The program works fine (does what it's supposed to and doesn't crash), but when I hit the "Randomize"-button I get a lot of errors (no crash or anything).
Anyone that could guide me in the right direction of determining the problem?
PS: If you see things that could be better, feel free to add as well.
package com.syntra.breweetristan;
import javafx.collections.*;
import javafx.fxml.*;
import javafx.scene.control.*;
public class Controller{
@FXML private ChoiceBox<String> cbox_opleiding = new ChoiceBox<>();
@FXML private ChoiceBox<String> cbox_module = new ChoiceBox<>();
@FXML private ChoiceBox<String> cbox_student = new ChoiceBox<>();
@FXML private TextArea txtarea_output;
//Randomizes the list of Courses, Seminars and Students
public void randomize(){
InnerLogicClass.initializeCourses();
cbox_opleiding.setItems(generateCourses());
cbox_opleiding.getSelectionModel().selectFirst();
cbox_module.getSelectionModel().selectFirst();
cbox_student.getSelectionModel().selectFirst();
}
//Adds the list of Seminars and Students corresponding to the selected course
public void courseSelected(){
String selectedCourseName = cbox_opleiding.getSelectionModel().getSelectedItem();
cbox_opleiding.getSelectionModel().select(selectedCourseName);
cbox_module.setItems(generateSeminars(selectedCourseName));
cbox_student.setItems(generateStudents(selectedCourseName));
cbox_module.getSelectionModel().selectFirst();
cbox_student.getSelectionModel().selectFirst();
}
//Outputs the requested info into txtarea_output
public void show(){
String courseName = cbox_opleiding.getSelectionModel().getSelectedItem();
String seminarName = cbox_module.getSelectionModel().getSelectedItem();
String studentName = cbox_student.getSelectionModel().getSelectedItem();
if (cbox_opleiding.getItems().size() == 1){
txtarea_output.setText("There is no information generated.\n" +
"Please click the \"Randomize\"-button.");
}
else if (courseName.equals("*")){
txtarea_output.setText(Output.outputEverything());
}
else {
if (seminarName.equals("*") && studentName.equals("*"))
txtarea_output.setText(Output.outputSingleCourse(courseName));
if (!seminarName.equals("*") && studentName.equals("*"))
txtarea_output.setText(Output.outputSingleSeminar(courseName, seminarName));
if (seminarName.equals("*") && !studentName.equals("*"))
txtarea_output.setText(Output.outputStudentComplete(courseName, studentName));
if (!seminarName.equals("*") && !studentName.equals("*"))
txtarea_output.setText(Output.outputSingleSeminarOfSingleStudent(courseName, seminarName, studentName));
}
}
@FXML
private void initialize() {
cbox_opleiding.getItems().set(0, "*");
cbox_module.getItems().set(0, "*");
cbox_student.getItems().set(0, "*");
cbox_opleiding.getSelectionModel().selectFirst();
cbox_module.getSelectionModel().selectFirst();
cbox_student.getSelectionModel().selectFirst();
cbox_opleiding.valueProperty().addListener(e -> {
courseSelected();
});
}
//Gets and returns an ObservableList<String> of the Courses
private ObservableList<String> generateCourses(){
ObservableList<String> coursesList = FXCollections.observableArrayList();
coursesList.add("*");
for (Course course : InnerLogicClass.getCourses()) {
coursesList.add(course.getName());
}
return coursesList;
}
//Gets and returns an ObservableList<String> of the Seminars corresponding with the current selected Course
//Parameter: the selected course as String
private ObservableList<String> generateSeminars(String courseName){
ObservableList<String> seminarsList = FXCollections.observableArrayList();
seminarsList.add("*");
if (!courseName.equals("*")) {
for (Course course : InnerLogicClass.getCourses()) {
if (courseName.equals(course.getName())) {
for (Seminar seminar : course.getSeminars()) {
seminarsList.add(seminar.getName());
}
break;
}
}
}
return seminarsList;
};
//Gets and returns an ObservableList<String> of the Students corresponding with the current selected Course
//Parameter: the selected course as String
private ObservableList<String> generateStudents(String courseName){
ObservableList<String> studentsList = FXCollections.observableArrayList();
studentsList.add("*");
if (!courseName.equals("*")) {
for (Course course : InnerLogicClass.getCourses()) {
if (courseName.equals(course.getName())){
for (Student student : course.getStudents()){
studentsList.add(student.getName());
}
break;
}
}
}
return studentsList;
}
}
<?xml version="1.0" encoding="UTF-8"?>
<?import java.lang.*?>
<?import javafx.collections.*?>
<?import javafx.geometry.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.text.*?>
<BorderPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="500.0"
prefWidth="750.0" xmlns="http://javafx.com/javafx/10.0.2-internal" xmlns:fx="http://javafx.com/fxml/1"
fx:controller="com.syntra.breweetristan.Controller">
<padding>
<Insets bottom="10.0" left="10.0" right="10.0" top="10.0" />
</padding>
<top>
<VBox prefHeight="110.0" prefWidth="730.0" spacing="10.0" BorderPane.alignment="CENTER">
<HBox prefHeight="55.0" prefWidth="200.0" spacing="10.0">
<VBox.margin>
<Insets/>
</VBox.margin>
<Button mnemonicParsing="false" onAction="#randomize" prefHeight="50.0"
prefWidth="360.0" text="Randomize"/>
<Button mnemonicParsing="false" onAction="#show" prefHeight="50.0" prefWidth="360.0"
text="Show"/>
</HBox>
<HBox prefHeight="20.0" prefWidth="200.0" spacing="10.0">
<Label prefHeight="20.0" prefWidth="236.0" text="Opleiding:"/>
<Label prefHeight="20.0" prefWidth="236.0" text="Module:"/>
<Label prefHeight="20.0" prefWidth="236.0" text="Student:"/>
</HBox>
<HBox prefHeight="55.0" prefWidth="200.0" spacing="10.0">
<ChoiceBox fx:id="cbox_opleiding" prefHeight="20.0" prefWidth="236.0">
<items>
<FXCollections fx:factory="observableArrayList">
<String fx:value="*"/>
</FXCollections>
</items>
<value>
<String fx:value="*"/>
</value>
</ChoiceBox>
<ChoiceBox fx:id="cbox_module" prefHeight="20.0" prefWidth="236.0">
<items>
<FXCollections fx:factory="observableArrayList">
<String fx:value="*"/>
</FXCollections>
</items>
<value>
<String fx:value="*"/>
</value>
</ChoiceBox>
<ChoiceBox fx:id="cbox_student" prefHeight="20.0" prefWidth="236.0">
<items>
<FXCollections fx:factory="observableArrayList">
<String fx:value="*"/>
</FXCollections>
</items>
<value>
<String fx:value="*"/>
</value>
</ChoiceBox>
</HBox>
</VBox>
</top>
<center>
<ScrollPane prefHeight="200.0" prefWidth="200.0" BorderPane.alignment="CENTER">
<content>
<AnchorPane minHeight="0.0" minWidth="0.0" prefHeight="368.0" prefWidth="728.0">
<children>
<TextArea fx:id="txtarea_output" editable="false" prefHeight="370.0" prefWidth="730.0" text="Press the "Randomize"-button to start.">
<font>
<Font name="Courier New" size="12.0" />
</font>
</TextArea>
</children>
</AnchorPane>
</content>
</ScrollPane>
</center>
</BorderPane>
Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
at com.syntra.breweetristan.Controller.generateSeminars(Controller.java:86)
at com.syntra.breweetristan.Controller.courseSelected(Controller.java:27)
at com.syntra.breweetristan.Controller.lambda$initialize$0(Controller.java:67)
at com.sun.javafx.binding.ExpressionHelper$Generic.fireValueChangedEvent(ExpressionHelper.java:349)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
at javafx.beans.property.ObjectPropertyBase.fireValueChangedEvent(ObjectPropertyBase.java:105)
at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:112)
at javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:146)
at javafx.scene.control.ChoiceBox.setValue(ChoiceBox.java:336)
at javafx.scene.control.ChoiceBox.lambda$new$137(ChoiceBox.java:190)
at com.sun.javafx.binding.ExpressionHelper$Generic.fireValueChangedEvent(ExpressionHelper.java:361)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
at javafx.beans.property.ReadOnlyObjectPropertyBase.fireValueChangedEvent(ReadOnlyObjectPropertyBase.java:74)
at javafx.beans.property.ReadOnlyObjectWrapper.fireValueChangedEvent(ReadOnlyObjectWrapper.java:102)
at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:112)
at javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:146)
at javafx.scene.control.SelectionModel.setSelectedItem(SelectionModel.java:102)
at javafx.scene.control.SingleSelectionModel.updateSelectedIndex(SingleSelectionModel.java:223)
at javafx.scene.control.SingleSelectionModel.clearSelection(SingleSelectionModel.java:68)
at javafx.scene.control.ChoiceBox$3.invalidated(ChoiceBox.java:255)
at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:111)
at javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:146)
at javafx.scene.control.ChoiceBox.setItems(ChoiceBox.java:273)
at com.syntra.breweetristan.Controller.randomize(Controller.java:17)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1771)
at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1657)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Node.fireEvent(Node.java:8411)
at javafx.scene.control.Button.fire(Button.java:185)
at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:182)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:96)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3757)
at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:394)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$353(GlassViewEventHandler.java:432)
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:431)
at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
at com.sun.glass.ui.View.notifyMouse(View.java:937)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$147(WinApplication.java:177)
at java.lang.Thread.run(Thread.java:748)
Process finished with exit code 0
