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

*** 25,34 ****
--- 25,35 ----
  
  package java.awt.image;
  
  import java.awt.Transparency;
  import java.awt.color.ColorSpace;
+ import java.util.Arrays;
  
  /**
   * The {@code PackedColorModel} class is an abstract
   * {@link ColorModel} class that works with pixel values which represent
   * color and alpha information as separate samples and which pack all
*** 86,95 ****
--- 87,97 ----
  
  public abstract class PackedColorModel extends ColorModel {
      int[] maskArray;
      int[] maskOffsets;
      float[] scaleFactors;
+     private volatile int hashCode;
  
      /**
       * Constructs a {@code PackedColorModel} from a color mask array,
       * which specifies which bits in an {@code int} pixel representation
       * contain each of the color samples, and an alpha mask.  Color
*** 383,405 ****
                                            raster.getHeight(), x, y,
                                            band);
      }
  
      /**
!      * Tests if the specified {@code Object} is an instance
!      * of {@code PackedColorModel} and equals this
       * {@code PackedColorModel}.
       * @param obj the {@code Object} to test for equality
       * @return {@code true} if the specified {@code Object}
!      * is an instance of {@code PackedColorModel} and equals this
!      * {@code PackedColorModel}; {@code false} otherwise.
       */
      public boolean equals(Object obj) {
!         if (!(obj instanceof PackedColorModel)) {
!             return false;
!         }
! 
          if (!super.equals(obj)) {
              return false;
          }
  
          PackedColorModel cm = (PackedColorModel) obj;
--- 385,410 ----
                                            raster.getHeight(), x, y,
                                            band);
      }
  
      /**
!      * Tests if the specified {@code Object} equals this
       * {@code PackedColorModel}.
+      * 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 {equals}.
       * @param obj the {@code Object} to test for equality
       * @return {@code true} if the specified {@code Object}
!      * equals this {@code PackedColorModel}; {@code false} otherwise.
       */
+     @Override
      public boolean equals(Object obj) {
!         /*
!          * We verify the type of argument obj in super.equals() where we check
!          * for equality of class name.
!          */
          if (!super.equals(obj)) {
              return false;
          }
  
          PackedColorModel cm = (PackedColorModel) obj;
*** 410,419 ****
--- 415,440 ----
              }
          }
          return true;
      }
  
+     /**
+      * Returns the hash code for this PackedColorModel.
+      *
+      * @return    a hash code for this PackedColorModel.
+      */
+     @Override
+     public int hashCode() {
+         int result = hashCode;
+         if (result == 0) {
+             result = super.hashCode();
+             result = 89 * result + Arrays.hashCode(this.maskArray);
+             hashCode = result;
+         }
+         return result;
+     }
+ 
      private static final int[] createBitsArray(int[]colorMaskArray,
                                                 int alphaMask) {
          int numColors = colorMaskArray.length;
          int numAlpha = (alphaMask == 0 ? 0 : 1);
          int[] arr = new int[numColors+numAlpha];