Address reliance on default constructors in the javax.swing.plaf APIs

Summary

Add explicit constructors to API classes of javax.swing.plaf that have default constructors

Problem

Default constructors are not recommended for classes that are parts of a formal API.

Solution

Add protected constructors to the public abstract classes and explicit no-arg constructors to public class

Specification

--- old/src/java.desktop/share/classes/javax/swing/plaf/ButtonUI.java   2020-08-12 22:09:48.900867200 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/ButtonUI.java   2020-08-12 22:09:46.368861700 +0530
@@ -36,4 +36,8 @@
  * @author Jeff Dinkins
  */
 public abstract class ButtonUI extends ComponentUI {
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected ButtonUI() {}
 }
--- old/src/java.desktop/share/classes/javax/swing/plaf/ColorChooserUI.java 2020-08-12 22:10:03.013587700 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/ColorChooserUI.java 2020-08-12 22:10:00.546887300 +0530
@@ -37,5 +37,8 @@

 public abstract class ColorChooserUI extends ComponentUI
 {
-
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected ColorChooserUI() {}
 }
--- old/src/java.desktop/share/classes/javax/swing/plaf/ComboBoxUI.java 2020-08-12 22:10:16.673615000 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/ComboBoxUI.java 2020-08-12 22:10:14.273384000 +0530
@@ -36,6 +36,11 @@
 public abstract class ComboBoxUI extends ComponentUI {

     /**
+     * Constructor for subclasses to call.
+     */
+    protected ComboBoxUI() {}
+
+    /**
      * Set the visibility of the popup
      *
      * @param c a {@code JComboBox}
--- old/src/java.desktop/share/classes/javax/swing/plaf/DesktopIconUI.java  2020-08-12 22:10:30.461344600 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/DesktopIconUI.java  2020-08-12 22:10:28.100683500 +0530
@@ -32,4 +32,8 @@
  * @author David Kloba
  */
 public abstract class DesktopIconUI extends ComponentUI {
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected DesktopIconUI() {}
 }
--- old/src/java.desktop/share/classes/javax/swing/plaf/DesktopPaneUI.java  2020-08-12 22:10:44.026540300 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/DesktopPaneUI.java  2020-08-12 22:10:41.640191000 +0530
@@ -32,4 +32,8 @@
  * @author David Kloba
  */
 public abstract class DesktopPaneUI extends ComponentUI {
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected DesktopPaneUI() {}
 }
--- old/src/java.desktop/share/classes/javax/swing/plaf/FileChooserUI.java  2020-08-12 22:10:57.531842200 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/FileChooserUI.java  2020-08-12 22:10:55.169376700 +0530
@@ -39,6 +39,11 @@
 public abstract class FileChooserUI extends ComponentUI
 {
     /**
+     * Constructor for subclasses to call.
+     */
+    protected FileChooserUI() {}
+
+    /**
      * Returns an accept-all file filter.
      * @param fc the file chooser
      * @return an accept-all file filter
--- old/src/java.desktop/share/classes/javax/swing/plaf/InternalFrameUI.java    2020-08-12 22:11:11.857373800 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/InternalFrameUI.java    2020-08-12 22:11:09.390778100 +0530
@@ -31,4 +31,8 @@
  * @author David Kloba
  */
 public abstract class InternalFrameUI extends ComponentUI {
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected InternalFrameUI() {}
 }
--- old/src/java.desktop/share/classes/javax/swing/plaf/LabelUI.java    2020-08-12 22:11:25.728276500 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/LabelUI.java    2020-08-12 22:11:23.258546900 +0530
@@ -31,4 +31,9 @@
  * @author Hans Muller
  */
 public abstract class LabelUI extends ComponentUI {
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected LabelUI() {}
 }
+
--- old/src/java.desktop/share/classes/javax/swing/plaf/LayerUI.java    2020-08-12 22:11:39.737017700 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/LayerUI.java    2020-08-12 22:11:36.863306000 +0530
@@ -66,6 +66,11 @@
             new PropertyChangeSupport(this);

     /**
+     * Constructs a {@code LayerUI}.
+     */
+    public LayerUI() {}
+
+    /**
      * Paints the specified component.
      * Subclasses should override this method and use
      * the specified {@code Graphics} object to
--- old/src/java.desktop/share/classes/javax/swing/plaf/ListUI.java 2020-08-12 22:11:54.611544400 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/ListUI.java 2020-08-12 22:11:51.979139800 +0530
@@ -39,6 +39,11 @@
 public abstract class ListUI extends ComponentUI
 {
     /**
+     * Constructor for subclasses to call.
+     */
+    protected ListUI() {}
+
+    /**
      * Returns the cell index in the specified {@code JList} closest to the
      * given location in the list's coordinate system. To determine if the
      * cell actually contains the specified location, compare the point against
--- old/src/java.desktop/share/classes/javax/swing/plaf/MenuBarUI.java  2020-08-12 22:12:09.338185400 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/MenuBarUI.java  2020-08-12 22:12:06.750215400 +0530
@@ -36,4 +36,9 @@
  * @author David Karlton
  */

-public abstract class MenuBarUI extends ComponentUI { }
+public abstract class MenuBarUI extends ComponentUI {
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected MenuBarUI() {}
+}
--- old/src/java.desktop/share/classes/javax/swing/plaf/MenuItemUI.java 2020-08-12 22:12:24.576590600 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/MenuItemUI.java 2020-08-12 22:12:21.838225700 +0530
@@ -35,4 +35,8 @@
  * @author Arnaud Weber
  */
 public abstract class MenuItemUI extends ButtonUI {
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected MenuItemUI() {}
 }
--- old/src/java.desktop/share/classes/javax/swing/plaf/OptionPaneUI.java   2020-08-12 22:12:39.160040800 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/OptionPaneUI.java   2020-08-12 22:12:36.624731500 +0530
@@ -36,6 +36,11 @@
 public abstract class OptionPaneUI extends ComponentUI
 {
     /**
+     * Constructor for subclasses to call.
+     */
+    protected OptionPaneUI() {}
+
+    /**
      * Requests the component representing the default value to have
      * focus.
      *
--- old/src/java.desktop/share/classes/javax/swing/plaf/PanelUI.java    2020-08-12 22:12:54.053591200 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/PanelUI.java    2020-08-12 22:12:51.411508200 +0530
@@ -32,4 +32,8 @@
  * @author Steve Wilson
  */
 public abstract class PanelUI extends ComponentUI {
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected PanelUI() {}
 }
--- old/src/java.desktop/share/classes/javax/swing/plaf/PopupMenuUI.java    2020-08-12 22:13:11.416643200 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/PopupMenuUI.java    2020-08-12 22:13:08.931329400 +0530
@@ -39,6 +39,11 @@

 public abstract class PopupMenuUI extends ComponentUI {
     /**
+     * Constructor for subclasses to call.
+     */
+    protected PopupMenuUI() {}
+
+    /**
      * Returns whether or not the given {@code MouseEvent} is the popup menu
      * trigger event for the platform
      *
--- old/src/java.desktop/share/classes/javax/swing/plaf/ProgressBarUI.java  2020-08-12 22:13:25.694478900 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/ProgressBarUI.java  2020-08-12 22:13:23.175249700 +0530
@@ -32,4 +32,8 @@
  * @author Rob Davis
  */
 public abstract class ProgressBarUI extends ComponentUI {
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected ProgressBarUI() {}
 }
--- old/src/java.desktop/share/classes/javax/swing/plaf/RootPaneUI.java 2020-08-12 22:13:46.086282600 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/RootPaneUI.java 2020-08-12 22:13:42.905969700 +0530
@@ -32,4 +32,8 @@
  * @since 1.3
  */
 public abstract class RootPaneUI extends ComponentUI {
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected RootPaneUI() {}
 }
--- old/src/java.desktop/share/classes/javax/swing/plaf/ScrollBarUI.java    2020-08-12 22:14:05.895068600 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/ScrollBarUI.java    2020-08-12 22:14:02.708088600 +0530
@@ -31,4 +31,8 @@
  * @author David Kloba
  */
 public abstract class ScrollBarUI extends ComponentUI {
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected ScrollBarUI() {}
 }
--- old/src/java.desktop/share/classes/javax/swing/plaf/ScrollPaneUI.java   2020-08-12 22:14:23.372974200 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/ScrollPaneUI.java   2020-08-12 22:14:20.727696000 +0530
@@ -33,4 +33,8 @@
  */

 public abstract class ScrollPaneUI extends ComponentUI {
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected ScrollPaneUI() {}
 }
--- old/src/java.desktop/share/classes/javax/swing/plaf/SeparatorUI.java    2020-08-12 22:14:38.588331200 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/SeparatorUI.java    2020-08-12 22:14:36.114010800 +0530
@@ -33,4 +33,8 @@
  */

 public abstract class SeparatorUI extends ComponentUI {
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected SeparatorUI() {}
 }
--- old/src/java.desktop/share/classes/javax/swing/plaf/SliderUI.java   2020-08-12 22:14:53.345389300 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/SliderUI.java   2020-08-12 22:14:50.713931900 +0530
@@ -31,4 +31,8 @@
  * @author Hans Muller
  */
 public abstract class SliderUI extends ComponentUI {
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected SliderUI() {}
 }
--- old/src/java.desktop/share/classes/javax/swing/plaf/SpinnerUI.java  2020-08-12 22:15:08.358643300 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/SpinnerUI.java  2020-08-12 22:15:05.433697700 +0530
@@ -33,4 +33,8 @@
  * @since 1.4
  */
 public abstract class SpinnerUI extends javax.swing.plaf.ComponentUI {
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected SpinnerUI() {}
 }
--- old/src/java.desktop/share/classes/javax/swing/plaf/SplitPaneUI.java    2020-08-12 22:15:25.724250500 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/SplitPaneUI.java    2020-08-12 22:15:23.154363600 +0530
@@ -36,6 +36,11 @@
 public abstract class SplitPaneUI extends ComponentUI
 {
     /**
+     * Constructor for subclasses to call.
+     */
+    protected SplitPaneUI() {}
+
+    /**
      * Messaged to relayout the JSplitPane based on the preferred size
      * of the children components.
      *
--- old/src/java.desktop/share/classes/javax/swing/plaf/TabbedPaneUI.java   2020-08-12 22:15:40.532491800 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/TabbedPaneUI.java   2020-08-12 22:15:38.058157300 +0530
@@ -36,6 +36,11 @@
  */
 public abstract class TabbedPaneUI extends ComponentUI {
     /**
+     * Constructor for subclasses to call.
+     */
+    protected TabbedPaneUI() {}
+
+    /**
      * Returns the tab for the coordinate.
      * @param pane the pane
      * @param x the x coordinate
--- old/src/java.desktop/share/classes/javax/swing/plaf/TableHeaderUI.java  2020-08-12 22:15:56.144397000 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/TableHeaderUI.java  2020-08-12 22:15:53.271026500 +0530
@@ -31,4 +31,8 @@
  * @author Alan Chung
  */
 public abstract class TableHeaderUI extends ComponentUI {
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected TableHeaderUI() {}
 }
--- old/src/java.desktop/share/classes/javax/swing/plaf/TableUI.java    2020-08-12 22:16:12.799970000 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/TableUI.java    2020-08-12 22:16:09.716902600 +0530
@@ -31,4 +31,8 @@
  * @author Alan Chung
  */
 public abstract class TableUI extends ComponentUI {
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected TableUI() {}
 }
--- old/src/java.desktop/share/classes/javax/swing/plaf/TextUI.java 2020-08-12 22:16:31.339453500 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/TextUI.java 2020-08-12 22:16:28.643715700 +0530
@@ -38,6 +38,11 @@
 public abstract class TextUI extends ComponentUI
 {
     /**
+     * Constructor for subclasses to call.
+     */
+    protected TextUI() {}
+
+    /**
      * Converts the given location in the model to a place in
      * the view coordinate system.
      *
--- old/src/java.desktop/share/classes/javax/swing/plaf/ToolBarUI.java  2020-08-12 22:16:47.728381400 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/ToolBarUI.java  2020-08-12 22:16:45.075892600 +0530
@@ -35,4 +35,8 @@
  */

 public abstract class ToolBarUI extends ComponentUI {
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected ToolBarUI() {}
 }
--- old/src/java.desktop/share/classes/javax/swing/plaf/ToolTipUI.java  2020-08-12 22:17:02.549615600 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/ToolTipUI.java  2020-08-12 22:16:59.726694400 +0530
@@ -31,4 +31,8 @@
  * @author Dave Moore
  */
 public abstract class ToolTipUI extends ComponentUI {
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected ToolTipUI() {}
 }
--- old/src/java.desktop/share/classes/javax/swing/plaf/TreeUI.java 2020-08-12 22:17:17.432522700 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/TreeUI.java 2020-08-12 22:17:14.954537600 +0530
@@ -38,6 +38,11 @@
 public abstract class TreeUI extends ComponentUI
 {
     /**
+     * Constructor for subclasses to call.
+     */
+    protected TreeUI() {}
+
+    /**
      * Returns the Rectangle enclosing the label portion that the
      * last item in path will be drawn into.  Will return null if
      * any component in path is currently valid.
--- old/src/java.desktop/share/classes/javax/swing/plaf/ViewportUI.java 2020-08-12 22:17:34.490939000 +0530
+++ new/src/java.desktop/share/classes/javax/swing/plaf/ViewportUI.java 2020-08-12 22:17:31.787581200 +0530
@@ -32,4 +32,8 @@
  * @author Rich Schiavi
  */
 public abstract class ViewportUI extends ComponentUI {
+    /**
+     * Constructor for subclasses to call.
+     */
+    protected ViewportUI() {}
 }