Question

I’m presently refactoring a JTable which displays a multitude of different types of data. The primary reason for this refactoring is that there a few ClassCastExceptions (the author/friend who wrote the code is off on hiatus), and I can’t seem to find where these are originating from. Due to the large codebase, I’m at a loss as to where to start. Does anyone have any suggestions? I realize and apologize for the ambiguity of this question!

I’ve included the stack trace below. Thanks!!

Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Boolean
    at javax.swing.JTable$BooleanRenderer.getTableCellRendererComponent(Unknown Source)
    at javax.swing.JTable.prepareRenderer(Unknown Source)
    at javax.swing.plaf.basic.BasicTableUI.paintCell(Unknown Source)
    at javax.swing.plaf.basic.BasicTableUI.paintCells(Unknown Source)
    at javax.swing.plaf.basic.BasicTableUI.paint(Unknown Source)
    at javax.swing.plaf.ComponentUI.update(Unknown Source)
    at javax.swing.JComponent.paintComponent(Unknown Source)
    at javax.swing.JComponent.paint(Unknown Source)
    at javax.swing.JComponent.paintToOffscreen(Unknown Source)
    at javax.swing.BufferStrategyPaintManager.paint(Unknown Source)
    at javax.swing.RepaintManager.paint(Unknown Source)
    at javax.swing.JComponent._paintImmediately(Unknown Source)
    at javax.swing.JComponent.paintImmediately(Unknown Source)
    at javax.swing.RepaintManager.paintDirtyRegions(Unknown Source)
    at javax.swing.RepaintManager.paintDirtyRegions(Unknown Source)
    at javax.swing.RepaintManager.seqPaintDirtyRegions(Unknown Source)
    at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(Unknown Source)
    at java.awt.event.InvocationEvent.dispatch(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)

Answer 1

This error which is occurring in BooleanRenderer is because it is expecting that the value that is from the table’s model is of type Boolean and tries to cast to it (akf’s answer has the exact line of code where it occurs).

My guess is that initially it was expected that the model would return Boolean values for the given column but at one point it is returning strings instead.
Therefore, I would concentrate on what model is being used for this given table (is it a custom model? Is it the default model where it is adding values to it?) and see where it may be getting a String instead of a Boolean.