java.lang.​IllegalAcc​essError when using a java class from within the file

When I use my JTableForMatlabMod in Matlab i get a java.lang.IllegalAccessError in the method that wants to instantiate a BtnCE object. Why can this be? BtnCE is in the same file as JTableForMatlabMod. I can use FilterData from JTableForMatlabMod with no problem. In an older version everything worked just fine. The only possible difference really is that I don't how the old version was compiled. I am using OpenJDK 1.7 and that's the only version with which I got it running at all.. Anyone got an idea?

// THIS ONE I CAN USE!
class FilterData {
     // lots of stuff left out here    
     // ...
}

class BtnCE extends AbstractCellEditor implements TableCellEditor, ActionListener, MouseListener {
    private final JButton editButton;
    private final JTable tbl;
    private boolean isButtonColumnEditor;

    public BtnCE(JTable table, String txt, Font myFont) {
        this.editButton = new JButton(txt);
        this.editButton.setFont(myFont);
        editButton.addActionListener(this);
        this.tbl = table;
        this.tbl.addMouseListener(this);
    }

    public Component getTableCellEditorComponent(JTable table, Object value, boolean isSelected, int row, int column) {
        return editButton;
    }

    @Override
    public Object getCellEditorValue() {
        return editButton.getText();
    }

    public void actionPerformed(ActionEvent e) {
        fireEditingStopped();
    }

    public void mousePressed(MouseEvent e) {
    }

    public void mouseReleased(MouseEvent e) {
        this.stopCellEditing();
        this.tbl.removeMouseListener(this);
    }

    public void mouseClicked(MouseEvent e) {
    }

    public void mouseEntered(MouseEvent e) {
    }

    public void mouseExited(MouseEvent e) {
    }
}

public class JTableForMatlabMod extends JTable {
   
    // lots of stuff left out here
    // ...

    @Override
    public TableCellEditor getCellEditor(int row, int column) {
        
        // lots of stuff left out here    
        // ...

        if ((this.btns != null) && (this.btns[this.convertRowIndexToModel(row)][modelColumn] == true))
            return new BtnCE(this, this.getValueAt(row, modelColumn).toString(), this.myFont);

        // lots of stuff left out here
        // ...

    }


    // lots of stuff left out here    
    // ...

}

Here's the java error text:

Exception in thread "AWT-EventQueue-0": java.lang.IllegalAccessError: BtnCE
	at JTableForMatlabMod.getCellEditor(JTableForMatlabMod.java:478)
	at javax.swing.JTable.editCellAt(JTable.java:3516)
	at javax.swing.plaf.basic.BasicTableUI$Handler.adjustSelection(BasicTableUI.java:1108)
	at javax.swing.plaf.basic.BasicTableUI$Handler.mousePressed(BasicTableUI.java:1038)
	at java.awt.AWTEventMulticaster.mousePressed(AWTEventMulticaster.java:280)
	at java.awt.Component.processMouseEvent(Component.java:6536)
	at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
	at java.awt.Component.processEvent(Component.java:6304)
	at java.awt.Container.processEvent(Container.java:2239)
	at java.awt.Component.dispatchEventImpl(Component.java:4889)
	at java.awt.Container.dispatchEventImpl(Container.java:2297)
	at java.awt.Component.dispatchEvent(Component.java:4711)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4904)
	at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4532)
	at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4476)
	at java.awt.Container.dispatchEventImpl(Container.java:2283)
	at java.awt.Window.dispatchEventImpl(Window.java:2746)
	at java.awt.Component.dispatchEvent(Component.java:4711)
	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:760)
	at java.awt.EventQueue.access$500(EventQueue.java:97)
	at java.awt.EventQueue$3.run(EventQueue.java:709)
	at java.awt.EventQueue$3.run(EventQueue.java:703)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:84)
	at java.awt.EventQueue$4.run(EventQueue.java:733)
	at java.awt.EventQueue$4.run(EventQueue.java:731)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:730)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
Exception "java.lang.ClassNotFoundException: com/intellij/codeInsight/editorActions/FoldingData"while constructing DataFlavor for: application/x-java-jvm-local-objectref; class=com.intellij.codeInsight.editorActions.FoldingData
Exception "java.lang.ClassNotFoundException: com/intellij/codeInsight/editorActions/FoldingData"while constructing DataFlavor for: application/x-java-jvm-local-objectref; class=com.intellij.codeInsight.editorActions.FoldingData
Exception "java.lang.ClassNotFoundException: com/intellij/codeInsight/editorActions/ReferenceData"while constructing DataFlavor for: application/x-java-jvm-local-objectref; class=com.intellij.codeInsight.editorActions.ReferenceData
Exception "java.lang.ClassNotFoundException: com/intellij/codeInsight/editorActions/ReferenceData"while constructing DataFlavor for: application/x-java-jvm-local-objectref; class=com.intellij.codeInsight.editorActions.ReferenceData

Answer 1

[Nikolaus Koopmann]

I solved it by putting BtnCE inside of JTableForMatlabMod as a nested class.