src/java.desktop/share/classes/java/awt/image/ComponentSampleModel.java

@@ -1185,23 +1185,70 @@
            }
            lineOffset += scanlineStride;
         }
     }
 
-    public boolean equals(Object o) {
-        if ((o == null) || !(o instanceof ComponentSampleModel)) {
+    /**
+     * Tests if the specified {@code Object} equals this
+     * {@code ComponentSampleModel}.
+     * In order to protect the symmetry property of
+     * {@code (a.equals(b) == b.equals(a))},
+     * the target object must be the same class (and not a subclass)
+     * as this object to evaluate as {@code equals}.
+     * <p>
+     * Subclasses may check additional properties, but this method
+     * will check the following basic properties for equivalence to
+     * determine if the target object equals this object:
+     *
+     * <ul>
+     * <li>Width in pixels of image data.
+     * <li>Height in pixels of image data.
+     * <li>Number of bands in the {@code ComponentSampleModel}.
+     * <li>Data type of the {@code DataBuffer} storing the pixel data.
+     * <li>Offsets for all bands in data array elements.
+     * <li>Index for each bank storing a band of image data.
+     * <li>The number of banks in the {@code ComponentSampleModel}.
+     * <li>Line stride of image data.
+     * <li>Pixel stride of image data.
+     * </ul>
+     * <p>
+     * Subclasses should override this method if they have any additional
+     * properties to compare and should use the following implementation.
+     * Note that the base {@code ComponentSampleModel} class already ensures
+     * that the target object is the same class as this object so the cast to
+     * the subclass type can be assumed if {@code super.equals(obj)} returns
+     * true.
+     * <pre>
+     *     public boolean equals(Object obj) {
+     *         if (!super.equals(obj)) {
+     *             return false;
+     *         }
+     *         MyCMClass cm = (MyCMClass) obj;
+     *         // test additional properties on "cm" and "this"
+     *     }
+     * </pre>
+     * <p>
+     * @param obj the {@code Object} to test for equality
+     * @return {@code true} if the specified {@code Object}
+     * equals this {@code ComponentSampleModel}; {@code false} otherwise.
+     */
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if ((obj == null) || (obj.getClass() !=  getClass())) {
             return false;
         }
 
-        ComponentSampleModel that = (ComponentSampleModel)o;
+        ComponentSampleModel that = (ComponentSampleModel)obj;
         return this.width == that.width &&
             this.height == that.height &&
             this.numBands == that.numBands &&
             this.dataType == that.dataType &&
             Arrays.equals(this.bandOffsets, that.bandOffsets) &&
             Arrays.equals(this.bankIndices, that.bankIndices) &&
-            this.numBands == that.numBands &&
             this.numBanks == that.numBanks &&
             this.scanlineStride == that.scanlineStride &&
             this.pixelStride == that.pixelStride;
     }