8365292: Remove javax.imageio.spi.ServiceRegistry.finalize()

src/java.desktop/share/classes/javax/imageio/spi/IIORegistry.java

@@ -44,7 +44,6 @@
 import com.sun.imageio.plugins.wbmp.WBMPImageWriterSpi;
 import com.sun.imageio.plugins.tiff.TIFFImageReaderSpi;
 import com.sun.imageio.plugins.tiff.TIFFImageWriterSpi;
-import sun.awt.AppContext;
 import java.util.List;
 import java.util.ServiceLoader;
 import java.util.ServiceConfigurationError;
@@ -105,25 +104,15 @@ private IIORegistry() {
         registerApplicationClasspathSpis();
     }
 
+    private static final IIORegistry registry = new IIORegistry();
+
     /**
      * Returns the default {@code IIORegistry} instance used by
      * the Image I/O API.  This instance should be used for all
      * registry functions.
-     *
-     * <p> Each {@code ThreadGroup} will receive its own instance.
-     *
-     * @return the default registry for the current
-     * {@code ThreadGroup}.
+     * @return the default registry for the Image I/O API
      */
     public static IIORegistry getDefaultInstance() {
-        AppContext context = AppContext.getAppContext();
-        IIORegistry registry =
-            (IIORegistry)context.get(IIORegistry.class);
-        if (registry == null) {
-            // Create an instance for this AppContext
-            registry = new IIORegistry();
-            context.put(IIORegistry.class, registry);
-        }
         return registry;
     }
 

src/java.desktop/share/classes/javax/imageio/spi/ServiceRegistry.java

@@ -78,7 +78,7 @@
  * proxy for the heavyweight service.
  *
  * <p> An application may customize the contents of a registry as it
- * sees fit, so long as it has the appropriate runtime permission.
+ * sees fit.
  *
  * <p> For information on how to create and deploy service providers,
  * refer to the documentation on {@link java.util.ServiceLoader ServiceLoader}
@@ -283,8 +283,7 @@ public <T> boolean registerServiceProvider(T provider,
      * {@code onRegistration} method will be called once for each
      * category it is registered under.  Its
      * {@code onDeregistration} method will be called each time
-     * it is deregistered from a category or when the registry is
-     * finalized.
+     * it is deregistered from a category.
      *
      * @param provider the service provider object to be registered.
      *
@@ -313,8 +312,7 @@ public void registerServiceProvider(Object provider) {
      * {@code onRegistration} method will be called once for each
      * category it is registered under.  Its
      * {@code onDeregistration} method will be called each time
-     * it is deregistered from a category or when the registry is
-     * finalized.
+     * it is deregistered from a category.
      *
      * @param providers an Iterator containing service provider
      * objects to be registered.
@@ -660,33 +658,19 @@ public void deregisterAll(Class<?> category) {
     /**
      * Deregisters all currently registered service providers from all
      * categories.
+     * <p>
+     * If an application creates a new {@code ServiceRegistry} instance and registers providers,
+     * and at some point no longer needs the instance, it should call this method to ensure
+     * that all providers which are instances of {@link RegisterableService}
+     * receive a {@link RegisterableService#onDeregistration(ServiceRegistry, Class<?>)} call back,
+     * before allowing the instance to be garbage collected.
      */
     public void deregisterAll() {
         for (SubRegistry reg : categoryMap.values()) {
             reg.clear();
         }
     }
 
-    /**
-     * Finalizes this object prior to garbage collection.  The
-     * {@code deregisterAll} method is called to deregister all
-     * currently registered service providers.  This method should not
-     * be called from application code.
-     *
-     * @throws Throwable if an error occurs during superclass
-     * finalization.
-     *
-     * @deprecated Finalization has been deprecated for removal.  See
-     * {@link java.lang.Object#finalize} for background information and details
-     * about migration options.
-     */
-    @Deprecated(since="9", forRemoval=true)
-    @SuppressWarnings("removal")
-    public void finalize() throws Throwable {
-        deregisterAll();
-        super.finalize();
-    }
-
     /**
      * Checks whether the provided class is one of the allowed
      * ImageIO service provider classes. If it is, returns normally.
@@ -821,10 +805,6 @@ public synchronized void clear() {
         poset.clear();
     }
 
-    @SuppressWarnings("removal")
-    public synchronized void finalize() {
-        clear();
-    }
 }