FULL PRODUCT VERSION :
java version "1.6.0-rc"


A DESCRIPTION OF THE PROBLEM :
I have identified these classes that at the minumum mention Hashtable in their implementation:
javax/swing/AbstractAction.java
javax/swing/ArrayTable.java
javax/swing/DebugGraphicsInfo.java
javax/swing/JComponent.java
javax/swing/JEditorPane.java
javax/swing/JLayeredPane.java
javax/swing/JMenu.java
javax/swing/JPopupMenu.java
javax/swing/JSlider.java
javax/swing/JTable.java
javax/swing/JToolBar.java
javax/swing/JTree.java
javax/swing/KeyboardManager.java
javax/swing/SwingUtilities.java
javax/swing/SystemEventQueueUtilities.java
javax/swing/UIDefaults.java
javax/swing/UIManager.java
javax/swing/plaf/basic/BasicFileChooserUI.java
javax/swing/plaf/basic/BasicTabbedPaneUI.java
javax/swing/plaf/basic/BasicTableUI.java
javax/swing/plaf/basic/BasicTextUI.java
javax/swing/plaf/basic/BasicToolBarUI.java
javax/swing/plaf/basic/BasicTreeUI.java
javax/swing/plaf/synth/SynthTabbedPaneUI.java
javax/swing/text/AbstractDocument.java
javax/swing/text/DefaultStyledDocument.java
javax/swing//text/JTextComponent.java
javax/swing/text/SimpleAttributeSet.java
javax/swing/text/Style.java
javax/swing/text/StyleContext.java
javax/swing/text/TextAction.java
javax/swing/text/TextLayoutStrategy.java
javax/swing/text/html/AccessibleHTML.java
javax/swing/text/html/CSS.java
javax/swing/text/html/HTML.java
javax/swing/text/html/HTMLDocument.java
javax/swing/text/html/MinimalHTMLWriter.java
javax/swing/text/html/StyleSheet.java
javax/swing/text/html/parser/AttributeList.java
javax/swing/text/html/parser/DTD.java
javax/swing/text/html/parser/Element.java
javax/swing/text/html/parser/Entity.java
javax/swing/text/html/parser/Parser.java
javax/swing/text/rtf/RTFAttributes.java
javax/swing/text/rtf/RTFGenerator.java
javax/swing/text/rtf/RTFReader.java
javax/swing/tree/DefaultTreeSelectionModel.java
javax/swing/tree/FixedHeightLayoutCache.java
javax/swing/tree/VariableHeightLayoutCache.java
javax/swing/undo/StateEdit.java
javax/swing/undo/StateEditable.java

Some like AbstractAction import Hashtable but do not use it.  Others like ArrayTable use a Hashtable for its storage.

The reason to convert would be to remove unnecessary synchronization.  Hashtable's methods are synchronized, HashMaps are not.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
read source, find usage

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
use HashMaps instead of Hashtables
ACTUAL -
Hashtables, everywhere!

REPRODUCIBILITY :
This bug can be reproduced always.

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read java source, their there
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