エラー表示

Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: -2
    at ThresholdByAverage.makeHistogram(ThresholdByAverage.java:141)
    at ThresholdByAverage.makeHistogramsBySize(ThresholdByAverage.java:192)
    at ThresholdByAverage.drawGraph(ThresholdByAverage.java:105)
    at CharacterRecognizer.drawGraph(CharacterRecognizer.java:99)
    at CharacterRecognizer2D.drawGraph(CharacterRecognizer2D.java:137)
    at RecognitionApp.recognitionTest(RecognitionApp.java:342)
    at RecognitionApp$FeatureListListener.actionPerformed(RecognitionApp.java:669)
    at javax.swing.JComboBox.fireActionEvent(JComboBox.java:1258)
    at javax.swing.JComboBox.setSelectedItem(JComboBox.java:586)
    at javax.swing.JComboBox.setSelectedIndex(JComboBox.java:622)
    at javax.swing.plaf.basic.BasicComboPopup$Handler.mouseReleased(BasicComboPopup.java:852)
    at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:290)
    at java.awt.Component.processMouseEvent(Component.java:6535)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
    at javax.swing.plaf.basic.BasicComboPopup$1.processMouseEvent(BasicComboPopup.java:501)
    at java.awt.Component.processEvent(Component.java:6300)
    at java.awt.Container.processEvent(Container.java:2236)
    at java.awt.Component.dispatchEventImpl(Component.java:4891)
    at java.awt.Container.dispatchEventImpl(Container.java:2294)
    at java.awt.Component.dispatchEvent(Component.java:4713)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)
    at java.awt.Container.dispatchEventImpl(Container.java:2280)
    at java.awt.Window.dispatchEventImpl(Window.java:2750)
    at java.awt.Component.dispatchEvent(Component.java:4713)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
    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:76)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
    at java.awt.EventQueue$4.run(EventQueue.java:731)
    at java.awt.EventQueue$4.run(EventQueue.java:729)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    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)

このエラーは何が起きてしまっているのでしょうか・・・