CODEWITHSUNDEEP
javaarraysarraylistnullpointerexceptionjavafx
p.lally
p.lally

Reputation: 17

NullPointerException when trying to .add list to a list of lists

I'm writing some code using JavaFX Scenebuilder 2.0 and Netbeans. I'm trying to make a UI work so that when a button is pressed on the page, all the info the user has entered into the fields on the page will be entered into an ArrayList. I then want to add this ArrayList to an ArrayList that will contain each smaller list. The goal is to then loop through the lists later to extract the data and make an output file with it. However, I'm having trouble getting the first list to be properly added to the larger list (I believe due to NullPointerException, although debugging with Javafx is kind of confusing so I'm not entirely sure). Here is my code:

List singleEndSample=new ArrayList<String>();
List<List> allSamples;

@FXML
private void addSample(ActionEvent event) {
    final int index = groups1.getSelectionModel().getSelectedIndex();
    if (index == -1) {noGroupError.setVisible(true);}
    else 
    {
        String name = libName.getText();
        String CV = cVar.getText();
        String insert = insertSize.getText();
        noGroupError.setVisible(false);
        if (singleEnd.isSelected()) {
            String location = singleReadLocation.getText();
            if (libName.getText().length() != 0) {
                if (singleReadLocation.getText().length() != 0) {
                    if (insertSize.getText().length() != 0) {
                        if (cVar.getText().length() != 0) {
                            singleEndSample.clear();
                            String sample = libName.getText();
                            samplesListView.add(sample);
                            sampleList.setItems(samplesListView);
                            singleEndSample.add((String) listViewItems.get(index));
                            singleEndSample.add(name);
                            singleEndSample.add(location);
                            singleEndSample.add(insert);
                            singleEndSample.add(CV);
                            allSamples.add(singleEndSample);
                            singleReadLocation.clear();
                            cVar.clear();
                            insertSize.clear();
                            libName.clear();
                        }
                    }
                }
            }
        }
    }

This is the error I get coming from the line "allSamples.add(singleEndSample);

Exception in thread "JavaFX Application Thread" java.lang.RuntimeException:    java.lang.reflect.InvocationTargetException
at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1762)
    at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1645)
    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.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:8216)
    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(CompositeEven    tHandler.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.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$MouseHandler.process(Scene.java:3724)
    at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3452)
    at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1728)
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2461)
    at     com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java    :348)
    at     com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java    :273)
    at java.security.AccessController.doPrivileged(Native Method)
    at     com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:382)
    at com.sun.glass.ui.View.handleMouseEvent(View.java:553)
    at com.sun.glass.ui.View.notifyMouse(View.java:925)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$141(WinApplication.java:102)
    at com.sun.glass.ui.win.WinApplication$$Lambda$37/96639997.run(Unknown Source)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
    at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
    at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1757)
    ... 51 more
Caused by: java.lang.NullPointerException
    at pipeline.ui.PipelineUIController.addSample(PipelineUIController.java:381)
    ... 61 more

please help!

Upvotes: 0

Views: 367

Answers (1)

bwegs
bwegs

Reputation: 3767

The problem appears to be that you never instantiate allSamples so when you try to access it in the line allSamples.add(singleEndSample); you are trying to access a null object. Because List is abstract and cannot be instantiated I'd suggest tweaking it to something like an ArrayList that can actually be implemented (isn't abstract).

One possible implementation might look like:

ArrayList singleEndSample=new ArrayList<String>();
List<ArrayList> allSamples = new ArrayList<ArrayList>();

Upvotes: 1

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