Summary

Add explicit constructors to some classes in Java AWT APIs which using default constructors.

Problem

Default constructors are not recommended for formal API classes.

Solution

Add the public constructors to the public/non-abstract classes, and protected constructors to the public/abstract classes.

Specification

src/java.desktop/share/classes/java/awt/ContainerOrderFocusTraversalPolicy.java

+    /**
+     * Constructs a {@code ContainerOrderFocusTraversalPolicy}.
+     */
+    public ContainerOrderFocusTraversalPolicy() {}

src/java.desktop/share/classes/java/awt/DefaultFocusTraversalPolicy.java

+    /**
+     * Constructs a {@code DefaultFocusTraversalPolicy}.
+     */
+    public DefaultFocusTraversalPolicy() {}

src/java.desktop/share/classes/java/awt/DefaultKeyboardFocusManager.java

+    /**
+     * Constructs a {@code DefaultKeyboardFocusManager}.
+     */
+    public DefaultKeyboardFocusManager() {}

src/java.desktop/share/classes/java/awt/FocusTraversalPolicy.java
 public abstract class FocusTraversalPolicy {

+    /**
+     * Constructs a {@code FocusTraversalPolicy}.
+     */
+    protected FocusTraversalPolicy() {}

src/java.desktop/share/classes/java/awt/Toolkit.java
 public abstract class Toolkit {

+    /**
+     * Constructs a {@code Toolkit}.
+     */
+    protected Toolkit() {}

src/java.desktop/share/classes/java/awt/dnd/DragSourceAdapter.java
     implements DragSourceListener, DragSourceMotionListener {

+    /**
+     * Constructs a {@code DragSourceAdapter}.
+     */
+    protected DragSourceAdapter() {}

src/java.desktop/share/classes/java/awt/dnd/DropTargetAdapter.java
 public abstract class DropTargetAdapter implements DropTargetListener {

+    /**
+     * Constructs a {@code DropTargetAdapter}.
+     */
+    protected DropTargetAdapter() {}

src/java.desktop/share/classes/java/awt/event/ComponentAdapter.java
 public abstract class ComponentAdapter implements ComponentListener {
+
+    /**
+     * Constructs a {@code ComponentAdapter}.
+     */
+    protected ComponentAdapter() {}

src/java.desktop/share/classes/java/awt/event/ContainerAdapter.java
 public abstract class ContainerAdapter implements ContainerListener {
+
+    /**
+     * Constructs a {@code ContainerAdapter}.
+     */
+    protected ContainerAdapter() {}

src/java.desktop/share/classes/java/awt/event/FocusAdapter.java
 public abstract class FocusAdapter implements FocusListener {
+
+    /**
+     * Constructs a {@code FocusAdapter}.
+     */
+    protected FocusAdapter() {}

src/java.desktop/share/classes/java/awt/event/HierarchyBoundsAdapter.java
 public abstract class HierarchyBoundsAdapter implements HierarchyBoundsListener
 {
+    /**
+     * Constructs a {@code HierarchyBoundsAdapter}.
+     */
+    protected HierarchyBoundsAdapter() {}

src/java.desktop/share/classes/java/awt/event/KeyAdapter.java
 public abstract class KeyAdapter implements KeyListener {
+
+    /**
+     * Constructs a {@code KeyAdapter}.
+     */
+    protected KeyAdapter() {}

src/java.desktop/share/classes/java/awt/event/MouseAdapter.java
 public abstract class MouseAdapter implements MouseListener, MouseWheelListener, MouseMotionListener {
+
+    /**
+     * Constructs a {@code MouseAdapter}.
+     */
+    protected MouseAdapter() {}

src/java.desktop/share/classes/java/awt/event/MouseMotionAdapter.java
 public abstract class MouseMotionAdapter implements MouseMotionListener {
+
+    /**
+     * Constructs a {@code MouseMotionAdapter}.
+     */
+    protected MouseMotionAdapter() {}

src/java.desktop/share/classes/java/awt/event/WindowAdapter.java
     public abstract class WindowAdapter implements WindowListener, WindowStateListener, WindowFocusListener
 {
+    /**
+     * Constructs a {@code WindowAdapter}.
+     */
+    protected WindowAdapter() {}

Link for convenience: http://cr.openjdk.java.net/~serb/8250856/webrev.00