"Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException" error

[keith_low]

Hi,

I am getting a "Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException" error in my code. I've been trying to find out where does it goes wrong but I haven't had any solution so far. Can I have some help here? The error message and my code are stated below:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.plaf.basic.BasicSplitPaneUI.paint(Unkn own Source)
at javax.swing.plaf.ComponentUI.update(Unknown Source)
at javax.swing.JComponent.paintComponent(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JComponent.paintChildren(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JComponent.paintChildren(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JComponent.paintChildren(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JComponent.paintChildren(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JComponent.paintToOffscreen(Unknown Source)
at javax.swing.RepaintManager$PaintManager.paintDoubl eBuffered(Unknown Source)
at javax.swing.RepaintManager$PaintManager.paint(Unkn own Source)
at javax.swing.RepaintManager.paint(Unknown Source)
at javax.swing.JComponent._paintImmediately(Unknown Source)
at javax.swing.JComponent.paintImmediately(Unknown Source)
at javax.swing.RepaintManager.paintDirtyRegions(Unkno wn Source)
at javax.swing.RepaintManager.paintDirtyRegions(Unkno wn Source)
at javax.swing.RepaintManager.seqPaintDirtyRegions(Un known Source)
at javax.swing.SystemEventQueueUtilities$ComponentWor kRequest.run(Unknown Source)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$000(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectio nPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(U nknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

public class CreateResourceCostReport extends JPanel implements ActionListener {
	private static final long serialVersionUID = 1L;
	static Map<String, Double> mpCostPerTraceMap = new HashMap<String, Double>();
	static Map<String, Double> mpCostPerResourceMap = new HashMap<String, Double>();
	static Map<String, Double> mpCostPerTraceAndResourceMap = new HashMap<String, Double>();
	static String strLogCurrency = null;
	JSplitPane jspOverallPanel = new JSplitPane();
	JPanel jpDisplayPanel = new JPanel();
	JPanel jpOptionPanel = new JPanel();
	JScrollPane jspDisplayScrollPane = new JScrollPane();
	Document dcDisplayDocument = null;
	JLabel jlChartInfo = new JLabel();
	JComboBox jcbChartInfo = new JComboBox();
	JLabel jlEmptyLabel = new JLabel();
	JLabel jlChartType = new JLabel();
	JComboBox jcbChartType = new JComboBox();
	boolean blScrollPane = false;
 
	public void GenerateResourceCostPerTraceReport (PluginContext context, XLog log) {
		XConceptExtension xceConceptExt = XConceptExtension.instance();
		Double dblTotal = 0.00;
		Double dblTotalPerResource = 0.00;
		String strResourceName = null;
 
		for (XTrace trace : log) {
			for (XEvent event : trace) {
				String strTraceID = xceConceptExt.extractName(trace);
				Collection<XAttribute> cltAttributes = event.getAttributes().values();
				Double dblCost = 0.00;
				boolean blResource = false;
				boolean blCost = false;
 
				for (XAttribute attribute : cltAttributes) {
					String strCostTypePrefix = "cost:type";
					String strResourcePrefix = "org:resource";
 
					if (attribute.getKey().startsWith("cost:currency")) {
						strLogCurrency = ((XAttributeLiteral) attribute).getValue();
					}
					if (attribute.getKey().startsWith(strResourcePrefix)) {
						strResourceName = ((XAttributeLiteral) attribute).getValue();
						blResource = true;
					}
					if (attribute.getKey().startsWith(strCostTypePrefix)) {
						dblCost = ((XAttributeContinuous) attribute).getValue();
						blCost = true;
					}
				}
 
				if (blResource == true && blCost == true) {
					Double dblTotalPerTrace = mpCostPerTraceMap.get(strTraceID);
					dblTotalPerResource = mpCostPerResourceMap.get(strResourceName);
					String strTraceIDResourceType = strTraceID + "\t" + strResourceName;
					Double dblTotalPerTraceAndResource = mpCostPerTraceAndResourceMap.get(strTraceIDResourceType);
 
					if (dblTotalPerTrace == null)
						mpCostPerTraceMap.put(strTraceID, dblCost);
					else
						mpCostPerTraceMap.put(strTraceID, dblTotalPerTrace + dblCost);
 
					if (dblTotalPerResource == null)
						mpCostPerResourceMap.put(strResourceName, dblCost);				
					else
						mpCostPerResourceMap.put(strResourceName, dblTotalPerResource += dblCost);
 
					if (dblTotalPerTraceAndResource == null)
						mpCostPerTraceAndResourceMap.put(strTraceIDResourceType, dblCost);
					else
						mpCostPerTraceAndResourceMap.put(strTraceIDResourceType, dblTotalPerTraceAndResource + dblCost);
					dblTotal += dblCost;
 
					blCost = false;
					blResource = false;
				}
				blResource = false;
			}
		}
	}
 
	private void GenerateDisplay() {
		jspOverallPanel = new JSplitPane();
		jpOptionPanel = new JPanel();
 
		jlChartInfo = new JLabel("Measure:");
		String[] strChartInfo = {"Cost per Resource", "Cost per Trace", "Cost per Task per Trace", "Cost per Resource per Trace"};
		jcbChartInfo = new JComboBox(strChartInfo);
 
		jlEmptyLabel = new JLabel("");
 
		jlChartType = new JLabel("Chart Type:");
		String[] strChartType = {"2D Pie Chart", "3D Pie Chart", "2D Bar Chart", "3D Bar Chart", "Waterfall Chart", "Multiple Bar Chart"};
		jcbChartType = new JComboBox(strChartType);
 
		GridLayout glGridLayout = new GridLayout(30,1);
		jpOptionPanel.setLayout(glGridLayout);
 
		jpOptionPanel.add(jlChartInfo);
		jpOptionPanel.add(jcbChartInfo);
		jpOptionPanel.add(jlEmptyLabel);
		jpOptionPanel.add(jlChartType);
		jpOptionPanel.add(jcbChartType);
	}
 
 	private JSplitPane Display(JPanel result) {
 		GenerateDisplay();
 
		jcbChartType.addActionListener(this);
 
		jpDisplayPanel = result;
 
		jspOverallPanel = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, jpOptionPanel, jpDisplayPanel);
		jspOverallPanel.setDividerLocation(200);
		jspOverallPanel.setDividerSize(3);
 
		setLayout(new BorderLayout());
		this.add(jspOverallPanel, BorderLayout.CENTER);
 
		this.repaint();
		this.revalidate();
 
		return jspOverallPanel;
	}
 
        private static JPanel CostReportPieChart2D() {
		JPanel pnlCostPanel = new JPanel();
		String[] strResource;
		Double[] dblCost;
		DefaultPieDataset  pdPieData  =  new  DefaultPieDataset();
		int intCount = 0;
 
		List<Entry<String, Double>> list = new ArrayList<Entry<String, Double>>(mpCostPerResourceMap.entrySet());
		Collections.sort(list, new StringMapComparator());
		strResource = new String[list.size()];
		dblCost = new Double[list.size()];
 
		for (Entry<String, Double> entry : list) {
			strResource[intCount] = entry.getKey();
			dblCost[intCount] = roundDouble(entry.getValue(),2);
			pdPieData.setValue(strResource[intCount] + " = " + dblCost[intCount].toString(), dblCost[intCount]);
			intCount += 1;
		}
 
		JFreeChart  jfcPieChart2D  =  ChartFactory.createPieChart(
			"Resource Consumption Cost",
			pdPieData,
			true,
			true,
			false	
		);
 
		PiePlot plot = (PiePlot) jfcPieChart2D.getPlot();
 
                plot.setNoDataMessage("No data to display");
 
		ChartPanel  cpDisplay  =  new  ChartPanel(jfcPieChart2D);
		cpDisplay.setPreferredSize(new java.awt.Dimension(50, 27));
		cpDisplay.setVisible(true);
		pnlCostPanel = cpDisplay;
 
		return pnlCostPanel;
	}
 
        Public JSplitPane CreateCostPerResourceReport(PluginContext context, XLog log) {
 
		GenerateResourceCostPerTraceReport(context, log);
 
		return Display(CostReportPieChart2D());
	}

Thanks in advance!

[Junky]

The stack trace of the error message that you posted only shows Java classes. If you keep reading down the full error message you will eventually see a class that you have written and a line number. This is where your NPE is happening.

[keith_low]

Hey, thanks for the reply. But this is the full stack of error message that I get. This is why I am having trouble in identifying the problem area.

[Junky]

No it is not the full error message. As I said somewhere further down in the stacktrace it will mention one or more of your classes. How are you compiling the code?

[JavaPF]

I can't attempt to compile this code because the imports and some other classes are missing..

[keith_low]

I'm currently using Eclipse to compile my code. Unfortunately this is really what I get from the error messages, all stated error at (Unknown Source). And yes, some classes are missing because I'm working with a customized environment, and I'm making use of the event log imports (thus the Public JSplitPane CreateCostPerResourceReport(PluginContext context, XLog log)).

[keith_low]

Oh I forgot to mention. Sometimes the compilation works, and sometimes it doesn't (50:50 chance). No error message were generated when it compiles successfully, whereas the above stated error message displayed when it failed to compile.

[xuancong]

This seems to be a JVM internal bug, either something wrong with JVM or Java native class' internal implementation. I frequently encounter this error when my matlab GUI, Eclipse Java and IE are running simultaneously. Sometimes, matlab GUI gives the following error:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at com.mathworks.mlwidgets.explorer.DocumentTableColu mns$11.compare(DocumentTableColumns.java:204)
at com.mathworks.mlwidgets.explorer.DocumentTableColu mns$11.compare(DocumentTableColumns.java:202)
at com.mathworks.mlwidgets.explorer.DocumentTableUtil s$2.compare(DocumentTableUtils.java:59)
at com.mathworks.mlwidgets.explorer.DocumentTableUtil s$2.compare(DocumentTableUtils.java:57)
at com.mathworks.mlwidgets.explorer.DocumentTableUtil s$1.compare(DocumentTableUtils.java:43)
at com.mathworks.mlwidgets.explorer.DocumentTableUtil s$1.compare(DocumentTableUtils.java:36)
at java.util.Arrays.mergeSort(Unknown Source)
at java.util.Arrays.mergeSort(Unknown Source)
at java.util.Arrays.mergeSort(Unknown Source)
at java.util.Arrays.mergeSort(Unknown Source)
at java.util.Arrays.mergeSort(Unknown Source)
at java.util.Arrays.mergeSort(Unknown Source)
at java.util.Arrays.mergeSort(Unknown Source)
at java.util.Arrays.sort(Unknown Source)
at java.util.Collections.sort(Unknown Source)
at com.mathworks.widgets.grouptable.GroupingTableMode l$17.run(GroupingTableModel.java:737)
at com.mathworks.widgets.grouptable.GroupingTableMode l$20.run(GroupingTableModel.java:929)
at com.mathworks.mwswing.MJUtilities.runOnEventDispat chThread(MJUtilities.java:823)
at com.mathworks.widgets.grouptable.GroupingTableMode l.runAndPreserveSelection(GroupingTableModel.java: 923)
at com.mathworks.widgets.grouptable.GroupingTableMode l.sort(GroupingTableModel.java:721)
at com.mathworks.widgets.grouptable.GroupingTable$3.m ouseClicked(GroupingTable.java:239)
at java.awt.AWTEventMulticaster.mouseClicked(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent( Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(U nknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unkno wn Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(U nknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

No matter how I close all programs which uses java (including explorer.exe), restart matlab, etc., it doesn't work. The only solution is to reboot or re-login your OS and everything works again.