run:Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException: String is null at sun.java2d.SunGraphics2D.drawString(SunGraphics2D.java:2744) at Exercise16_8$MovableMessagePanel.paintComponent(Exercise16_8.java:44) at javax.swing.JComponent.paint(JComponent.java:1029) at javax.swing.JComponent.paintChildren(JComponent.java:862) at javax.swing.JComponent.paint(JComponent.java:1038) at javax.swing.JComponent.paintChildren(JComponent.java:862) at javax.swing.JComponent.paint(JComponent.java:1038) at javax.swing.JLayeredPane.paint(JLayeredPane.java:567) at javax.swing.JComponent.paintChildren(JComponent.java:862) at javax.swing.JComponent.paintToOffscreen(JComponent.java:5131) at javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(RepaintManager.java:1479) at javax.swing.RepaintManager$PaintManager.paint(RepaintManager.java:1410) at javax.swing.RepaintManager.paint(RepaintManager.java:1224) at javax.swing.JComponent.paint(JComponent.java:1015) at java.awt.GraphicsCallback$PaintCallback.run(GraphicsCallback.java:21) at sun.awt.SunGraphicsCallback.runOneComponent(SunGraphicsCallback.java:60) at sun.awt.SunGraphicsCallback.runComponents(SunGraphicsCallback.java:97) at java.awt.Container.paint(Container.java:1780) at java.awt.Window.paint(Window.java:3375) at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:796) at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:713) at javax.swing.RepaintManager.seqPaintDirtyRegions(RepaintManager.java:693) at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(SystemEventQueueUtilities.java:125) at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209) at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:641) at java.awt.EventQueue.access$000(EventQueue.java:84) at java.awt.EventQueue$1.run(EventQueue.java:602) at java.awt.EventQueue$1.run(EventQueue.java:600) at java.security.AccessController.doPrivileged(Native Method) at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87) at java.awt.EventQueue.dispatchEvent(EventQueue.java:611) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161) at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException: String is null at sun.java2d.SunGraphics2D.drawString(SunGraphics2D.java:2744) at Exercise16_8$MovableMessagePanel.paintComponent(Exercise16_8.java:44) at javax.swing.JComponent.paint(JComponent.java:1029) at javax.swing.JComponent.paintChildren(JComponent.java:862) at javax.swing.JComponent.paint(JComponent.java:1038) at javax.swing.JComponent.paintChildren(JComponent.java:862) at javax.swing.JComponent.paint(JComponent.java:1038) at javax.swing.JLayeredPane.paint(JLayeredPane.java:567) at javax.swing.JComponent.paintChildren(JComponent.java:862) at javax.swing.JComponent.paintToOffscreen(JComponent.java:5131) at javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(RepaintManager.java:1479) at javax.swing.RepaintManager$PaintManager.paint(RepaintManager.java:1410) at javax.swing.RepaintManager.paint(RepaintManager.java:1224) at javax.swing.JComponent.paint(JComponent.java:1015) at java.awt.GraphicsCallback$PaintCallback.run(GraphicsCallback.java:21) at sun.awt.SunGraphicsCallback.runOneComponent(SunGraphicsCallback.java:60) at sun.awt.SunGraphicsCallback.runComponents(SunGraphicsCallback.java:97) at java.awt.Container.paint(Container.java:1780) at java.awt.Window.paint(Window.java:3375) at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:796) at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:713) at javax.swing.RepaintManager.seqPaintDirtyRegions(RepaintManager.java:693) at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(SystemEventQueueUtilities.java:125) at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209) at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:641) at java.awt.EventQueue.access$000(EventQueue.java:84) at java.awt.EventQueue$1.run(EventQueue.java:602) at java.awt.EventQueue$1.run(EventQueue.java:600) at java.security.AccessController.doPrivileged(Native Method) at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87) at java.awt.EventQueue.dispatchEvent(EventQueue.java:611) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161) at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)BUILD SUCCESSFUL (total time: 10 seconds)
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We get it - no one likes a content blocker. Take one extra minute and find out why we block content.
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I assume you have to handle the scenario where the str value is null to avoid Null pointer exception.
This null pointer exception will occur if any of the values str,x and y are 'null'.
Always ensure that some default values exists for str, x and y.
Directly initialize the str value as below at Line8 instead of new line
static String str = "";
Modify it accordingly as per the need.
It would be best practice to check for values before calling drawString() method.
Am P
Agreed with Expert (rams4javaexpert).
:)
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