Summary

Change methods like getSelectedItem to return the generic object, rather an Object which clients need to cast to appropriate type.

Problem

Add generics support to Swing components like JComboBox and JList:

JComboBox combo = new JComboBox(...);

String str = combo.getSelectedItem();

This provides more type safe code, and eliminates unnecessary casts in the client code.

Solution

Solution is straightforward change of return type / argument type to the functions returning/consuming contents of JComboBox/JList. Additionally, fix all the transitive compiler errors that result due to changing the method signatures. Here is the webrev containing the proposed changes: http://cr.openjdk.java.net/~kaddepalli/6303622/webrev00/

Specification

Providing the public methods that are being affected here: 1. src/java.desktop/share/classes/javax/swing/ComboBoxModel.java

   /**
    * Set the selected item. The implementation of this  method should notify
    * all registered <code>ListDataListener</code>s that the contents
    * have changed.
    *
    * @param <E> the type of the elements of this model.
    * @param anItem the list object to select or <code>null</code>
    *        to clear the selection
    */
    void setSelectedItem(E anItem);

    E getSelectedItem();

2. src/java.desktop/share/classes/javax/swing/DefaultCellEditor.java

      /**
       * Constructs a <code>DefaultCellEditor</code> object that uses a
       * combo box.
       *@param <E> the type of the elements of comboBox
       * @param comboBox  a <code>JComboBox</code> object
       */
      @SuppressWarnings("unchecked")
      public <E> DefaultCellEditor(final JComboBox<E> comboBox) { }

3. src/java.desktop/share/classes/javax/swing/DefaultComboBoxModel.java

    @Override
     public void setSelectedItem(E anObject) {}

     @Override
     public E getSelectedItem() {}

     public int getIndexOf(E anObject) {}

     public void removeElement(E anObject) {}

4. src/java.desktop/share/classes/javax/swing/DefaultListModel.java

    public void copyInto(E anArray[]) {}

    public boolean contains(E elem) {}

    public int indexOf(E elem) {}

    public int indexOf(E elem, int index) {}

    public int lastIndexOf(E elem) {}

    public int lastIndexOf(E elem, int index) {}

    public boolean removeElement(E obj) {}

5. src/java.desktop/share/classes/javax/swing/JComboBox.java

   /**
     * Sets the selected item in the combo box display area to the object in
     * the argument.
     * If <code>anObject</code> is in the list, the display area shows
     * <code>anObject</code> selected.
     * <p>
     * If <code>anObject</code> is <i>not</i> in the list and the combo box is
     * uneditable, it will not change the current selection. For editable
     * combo boxes, the selection will change to <code>anObject</code>.
     * <p>
     * If this constitutes a change in the selected item,
     * <code>ItemListener</code>s added to the combo box will be notified with
     * one or two <code>ItemEvent</code>s.
     * If there is a current selected item, an <code>ItemEvent</code> will be
     * fired and the state change will be <code>ItemEvent.DESELECTED</code>.
     * If <code>anObject</code> is in the list and is not currently selected
     * then an <code>ItemEvent</code> will be fired and the state change will
     * be <code>ItemEvent.SELECTED</code>.
     * <p>
     * <code>ActionListener</code>s added to the combo box will be notified
     * with an <code>ActionEvent</code> when this method is called.
     *
     * @param <E> the type of the elements of this comboBox.
     * @param anObject  the list object to select; use <code>null</code> to
                        clear the selection
     */
    @BeanProperty(bound = false, preferred = true, description
            = "Sets the selected item in the JComboBox.")
    public void setSelectedItem(E anObject) {}

    /**
     * Returns the current selected item.
     * <p>
     * If the combo box is editable, then this value may not have been added
     * to the combo box with <code>addItem</code>, <code>insertItemAt</code>
     * or the data constructors.
     *
     * @param <E> the type of the elements of comboBox.
     * @return the current selected Object
     * @see #setSelectedItem
     */
     public E getSelectedItem() {}

    /**
     * Removes an item from the item list.
     * This method works only if the <code>JComboBox</code> uses a
     * mutable data model.
     *
     * @param <E> the type of the elements of this comboBox.
     * @param anObject  the object to remove from the item list
     * @see MutableComboBoxModel
     */
     public void removeItem(E anObject) {}

6. src/java.desktop/share/classes/javax/swing/JList.java

   /**
    * Selects the specified object from the list.
    *
    * @param <E> the type of the elements of this JList.
    * @param anObject      the object to select
    * @param shouldScroll  {@code true} if the list should scroll to display
    *                      the selected object, if one exists; otherwise {@code false}
    */
     public void setSelectedValue(E anObject,boolean shouldScroll) {}

7. src/java.desktop/share/classes/javax/swing/MutableComboBoxModel.java

   /**
    * Removes an item from the model. The implementation of this method should
    * should notify all registered <code>ListDataListener</code>s that the
    * item has been removed.
    *
    * @param obj the <code>Object</code> to be removed
    */
    public void removeElement( E obj );

8. src/java.desktop/share/classes/javax/swing/text/html/OptionComboBoxModel.java

  class OptionComboBoxModel extends DefaultComboBoxModel<Option> implements Serializable {}

9. src/java.desktop/share/classes/javax/swing/text/html/OptionListModel.java

    class OptionListModel extends DefaultListModel<Option> implements ListSelectionModel, Serializable {

      public OptionListModel clone() throws CloneNotSupportedException {}
    }