Minor fixes to android.graphics.Matrix

Tweaked equals() and finalize(), introduced trivial hashCode().

(Also picked up a handful of automatic trailing-space removals.)

Bug 9756081

Change-Id: I4639cf1e970a16179fa6c0d24785f4d0dfbe58ed

graphics/java/android/graphics/Matrix.java

@@ -267,13 +267,23 @@ public class Matrix {
             native_set(native_instance, src.native_instance);
         }
     }
-    
+
     /** Returns true iff obj is a Matrix and its values equal our values.
     */
+    @Override
     public boolean equals(Object obj) {
-        return obj != null &&
-               obj instanceof Matrix &&
-               native_equals(native_instance, ((Matrix)obj).native_instance);
+        //if (obj == this) return true;     -- NaN value would mean matrix != itself
+        if (!(obj instanceof Matrix)) return false;
+        return native_equals(native_instance, ((Matrix)obj).native_instance);
+    }
+
+    @Override
+    public int hashCode() {
+        // This should generate the hash code by performing some arithmetic operation on all
+        // the matrix elements -- our equals() does an element-by-element comparison, and we
+        // need to ensure that the hash code for two equal objects is the same.  We're not
+        // really using this at the moment, so we take the easy way out.
+        return 44;
     }
 
     /** Set the matrix to identity */
@@ -512,7 +522,7 @@ public class Matrix {
          */
         END     (3);
 
-        // the native values must match those in SkMatrix.h 
+        // the native values must match those in SkMatrix.h
         ScaleToFit(int nativeInt) {
             this.nativeInt = nativeInt;
         }
@@ -535,7 +545,7 @@ public class Matrix {
         }
         return native_setRectToRect(native_instance, src, dst, stf.nativeInt);
     }
-    
+
     // private helper to perform range checks on arrays of "points"
     private static void checkPointArrays(float[] src, int srcIndex,
                                          float[] dst, int dstIndex,
@@ -598,7 +608,7 @@ public class Matrix {
         native_mapPoints(native_instance, dst, dstIndex, src, srcIndex,
                          pointCount, true);
     }
-    
+
     /**
     * Apply this matrix to the array of 2D vectors specified by src, and write
      * the transformed vectors into the array of vectors specified by dst. The
@@ -620,7 +630,7 @@ public class Matrix {
         native_mapPoints(native_instance, dst, dstIndex, src, srcIndex,
                          vectorCount, false);
     }
-    
+
     /**
      * Apply this matrix to the array of 2D points specified by src, and write
      * the transformed points into the array of points specified by dst. The
@@ -713,7 +723,7 @@ public class Matrix {
     public float mapRadius(float radius) {
         return native_mapRadius(native_instance, radius);
     }
-    
+
     /** Copy 9 values from the matrix into the array.
     */
     public void getValues(float[] values) {
@@ -736,13 +746,14 @@ public class Matrix {
         native_setValues(native_instance, values);
     }
 
+    @Override
     public String toString() {
         StringBuilder sb = new StringBuilder(64);
         sb.append("Matrix{");
         toShortString(sb);
         sb.append('}');
         return sb.toString();
-                
+
     }
 
     public String toShortString() {
@@ -780,13 +791,18 @@ public class Matrix {
                 pw.print(values[5]); pw.print("][");
         pw.print(values[6]); pw.print(", "); pw.print(values[7]); pw.print(", ");
                 pw.print(values[8]); pw.print(']');
-                
+
     }
 
+    @Override
     protected void finalize() throws Throwable {
-        finalizer(native_instance);
+        try {
+            finalizer(native_instance);
+        } finally {
+            super.finalize();
+        }
     }
-    
+
     /*package*/ final int ni() {
         return native_instance;
     }