Kernel.java: added add method

    added hashCode and equals
    updated test

src/main/java/de/zmt/pathfinding/filter/Kernel.java

 package de.zmt.pathfinding.filter;
 
 import java.io.Serializable;
+import java.util.Arrays;
 
 /**
  * Immutable Kernel for operation on double grids. A similar class already
@@ -53,7 +54,22 @@ public class Kernel implements Serializable {
     }
 
     /**
-     * Multiplies all weights by {@code scalar} and return result with a new
+     * Adds {@code value} to all weights and return results within a new object.
+     * 
+     * @param value
+     * @return new kernel object with added {@code value}
+     */
+    public Kernel add(double value) {
+	double[] addedWeights = new double[weights.length];
+	for (int i = 0; i < weights.length; i++) {
+	    addedWeights[i] = weights[i] + value;
+	}
+
+	return new Kernel(width, height, addedWeights);
+    }
+
+    /**
+     * Multiplies all weights by {@code scalar} and return results within a new
      * object.
      * 
      * @param scalar
@@ -120,6 +136,36 @@ public class Kernel implements Serializable {
 	return weights;
     }
 
+    @Override
+    public int hashCode() {
+	final int prime = 31;
+	int result = 1;
+	result = prime * result + Arrays.hashCode(weights);
+	result = prime * result + width;
+	return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+	if (this == obj) {
+	    return true;
+	}
+	if (obj == null) {
+	    return false;
+	}
+	if (getClass() != obj.getClass()) {
+	    return false;
+	}
+	Kernel other = (Kernel) obj;
+	if (!Arrays.equals(weights, other.weights)) {
+	    return false;
+	}
+	if (width != other.width) {
+	    return false;
+	}
+	return true;
+    }
+
     @Override
     public String toString() {
 	StringBuilder builder = new StringBuilder();

src/test/java/de/zmt/pathfinding/filter/KernelTest.java

@@ -10,12 +10,13 @@ import org.junit.Test;
 public class KernelTest {
     private static final int KERNEL_EXTENT = 3;
     private static final double MAX_ERROR = 1E-14d;
+    private static final double DOUBLE_SUM = KERNEL_EXTENT * KERNEL_EXTENT * 2d;
 
     private Kernel kernel;
 
     @Before
     public void setUp() throws Exception {
-	kernel = KernelFactory.createConstant(3, KERNEL_EXTENT);
+	kernel = KernelFactory.createConstant(KERNEL_EXTENT, KERNEL_EXTENT);
     }
 
     @Test
@@ -28,4 +29,17 @@ public class KernelTest {
 	assertThat(kernel.normalize().sum(), is(closeTo(1, MAX_ERROR)));
     }
 
+    @Test
+    public void add() {
+	assertThat(kernel.add(1).sum(), is(DOUBLE_SUM));
+    }
+
+    @Test
+    public void multiply() {
+	assertThat(kernel.multiply(2).sum(), is(DOUBLE_SUM));
+    }
+
+    public void equals() {
+	assertThat(new Kernel(1, 1, new double[] { 1 }), is(new Kernel(1, 1, new double[] { 1 })));
+    }
 }