Removed a bug in Matrix Multiplication and added Matrix Adition funktionality

src/main/java/com/ugsbo/matrixcalc/MatrixCalcMath.java

@@ -1,5 +1,7 @@
 package com.ugsbo.matrixcalc;
 
+import java.io.IOException;
+
 /**
  * Contains all basic matrix math calculations.
  */
@@ -28,7 +30,8 @@ public class MatrixCalcMath {
             }
             return result;
         } else {
-            throw new IllegalArgumentException("array must be linked");
+            return null;
+            //throw new IllegalArgumentException("Matricies must be linked");
         }
     }
 
@@ -41,15 +44,16 @@ public class MatrixCalcMath {
      * @return true if you can Muliply A with B false if not.
      */
     public boolean checkIfMatriciesAreLinked(double[][] matrixA, double[][] matrixB) {
-        if (matrixA != null) {
-            if (matrixA[0].length == matrixB.length) {
-                return true;
-            } else {
-                return false;
-            }
-        } else {
+        if (matrixA == null) {
+            return false;
+        }
+        if (matrixA.length == 0) {
             return false;
         }
+        if (matrixA[0].length == matrixB.length) {
+            return true;
+        }
+        return false;
     }
 
     /**
@@ -61,8 +65,20 @@ public class MatrixCalcMath {
      * @return The Matrixsum of matrix A and matrix B
      */
     public double[][] matrixAddition(double[][] matrixA, double[][] matrixB) {
-        // TODO Sum each Element of matrix A to the corrosponding elem in B
-        return null;
+        if (checkIfMatriciesAreTheSameDimension(matrixA, matrixB)) {
+            double[][] result = new double[matrixA.length][matrixA[0].length];
+            for (int rows = 0; rows < matrixA.length; rows++) {
+                for (int colums = 0; colums < matrixA[0].length; colums++) {
+                    result[rows][colums] = matrixA[rows][colums] + matrixB[rows][colums];
+                }
+            }
+            return result;
+        } else {
+            return null;
+            // TODO Fragen wie man eine Exception testen kann.
+            // throw new IllegalArgumentException("Matricies need to have the same
+            // Dimensions");
+        }
     }
 
     /**
@@ -74,7 +90,11 @@ public class MatrixCalcMath {
      * @return true if the Dimensions of Matrix A equals the Dimensions Matrix B
      */
     public boolean checkIfMatriciesAreTheSameDimension(double[][] matrixA, double[][] matrixB) {
-        // TODO Dimension check.
-        return false;
+        if (matrixA.length == matrixB.length && matrixA[0].length == matrixB[0].length) {
+            return true;
+        } else {
+            return false;
+        }
+
     }
 }

src/test/java/com/ugsbo/matrixcalc/MatrixAdditionTest.java

@@ -0,0 +1,61 @@
+package com.ugsbo.matrixcalc;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+
+/**
+ * Tests the funktionality to add two matricies
+ */
+public class MatrixAdditionTest {
+
+    @Test
+    public void twoMatriciesHaveTheSameDimensions() {
+        MatrixCalcMath math = new MatrixCalcMath();
+        double[][] matrixA = new double[1][1];
+        double[][] matrixB = new double[1][1];
+
+        boolean result = math.checkIfMatriciesAreTheSameDimension(matrixA, matrixB);
+
+        assertTrue("Two Matricies with the same Dimension were not detected as that", result);
+    }
+
+    @Test
+    public void twoMatriciesDONOTHaveTheSameDimensions() {
+        MatrixCalcMath math = new MatrixCalcMath();
+        double[][] matrixA = new double[2][1];
+        double[][] matrixB = new double[1][1];
+
+        boolean result = math.checkIfMatriciesAreTheSameDimension(matrixA, matrixB);
+
+        assertFalse("Two Matricies without the same Dimension were detected as that", result);
+    }
+
+    @Test
+    public void addTwoMatriciesWithSameContent() {
+        MatrixCalcMath math = new MatrixCalcMath();
+        double[][] matrixA = { { 1.0, 1.0 }, { 1.0, 1.0 } };
+        double[][] matrixB = { { 1.0, 1.0 }, { 1.0, 1.0 } };
+        double[][] matrixC = { { 2.0, 2.0 }, { 2.0, 2.0 } };
+
+        double[][] result = math.matrixAddition(matrixA, matrixB);
+
+        assertArrayEquals("The first row is not correct", matrixC[0], result[0], 0.1);
+        assertArrayEquals("The seound row is not correct", matrixC[1], result[1], 0.1);
+    }
+    
+    @Test
+    public void addTwoMatriciesWithDiffrentContent() {
+        MatrixCalcMath math = new MatrixCalcMath();
+        double[][] matrixA = { { 7.0, 3.0 }, { 2.0, 9.0 } };
+        double[][] matrixB = { { 6.0, 3.0 }, { 7.0, 11.0 } };
+        double[][] matrixC = { { 13.0, 6.0 }, { 9.0, 20.0 } };
+
+        double[][] result = math.matrixAddition(matrixA, matrixB);
+
+        assertArrayEquals("The first row is not correct", matrixC[0], result[0], 0.1);
+        assertArrayEquals("The seound row is not correct", matrixC[1], result[1], 0.1);
+    }
+}

src/test/java/com/ugsbo/matrixcalc/MatrixMultiplicationTest.java

@@ -1,10 +1,12 @@
 package com.ugsbo.matrixcalc;
 
 import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
 import org.junit.Test;
+import org.junit.internal.matchers.ThrowableCauseMatcher;
 
 /**
  * Testet die Matrix Multiplication funkionalität
@@ -16,8 +18,10 @@ public class MatrixMultiplicationTest {
         MatrixCalcMath math = new MatrixCalcMath();
         double[][] matrixA = new double[1][2];
         double[][] matrixB = new double[2][1];
-        assertTrue("Matrix A is Linked to B but it is not detected that way",
-                math.checkIfMatriciesAreLinked(matrixA, matrixB));
+
+        boolean result = math.checkIfMatriciesAreLinked(matrixA, matrixB);
+        
+        assertTrue("Matrix A is Linked to B but it is not detected that way", result);
     }
 
     @Test
@@ -25,7 +29,10 @@ public class MatrixMultiplicationTest {
         MatrixCalcMath math = new MatrixCalcMath();
         double[][] matrixA = null;
         double[][] matrixB = null;
-        assertFalse("Matrix A and B are null but detected as Linked", math.checkIfMatriciesAreLinked(matrixA, matrixB));
+
+        boolean result = math.checkIfMatriciesAreLinked(matrixA, matrixB);
+
+        assertFalse("Matrix A and B are null but detected as Linked", result);
     }
 
     @Test
@@ -33,8 +40,10 @@ public class MatrixMultiplicationTest {
         MatrixCalcMath math = new MatrixCalcMath();
         double[][] matrixA = new double[1][1];
         double[][] matrixB = new double[2][1];
-        assertFalse("Matrix A and B are not Linked but detected as Linked",
-                math.checkIfMatriciesAreLinked(matrixA, matrixB));
+
+        boolean result = math.checkIfMatriciesAreLinked(matrixA, matrixB);
+
+        assertFalse("Matrix A and B are not Linked but detected as Linked", result);
     }
 
     @Test
@@ -43,53 +52,62 @@ public class MatrixMultiplicationTest {
         double[][] matrixA = { { 1.0, 1.0 }, { 1.0, 1.0 } };
         double[][] matrixB = { { 1.0, 1.0 }, { 1.0, 1.0 } };
         double[][] matrixC = { { 2.0, 2.0 }, { 2.0, 2.0 } };
-        assertArrayEquals("The first row is not correct", matrixC[0], math.matrixMultiplication(matrixA, matrixB)[0],
-                0.1);
-        assertArrayEquals("The seound row is not correct", matrixC[1], math.matrixMultiplication(matrixA, matrixB)[1],
-                0.1);
+
+        double[][] result = math.matrixMultiplication(matrixA, matrixB);
+
+        assertArrayEquals("The first row is not correct", matrixC[0], result[0], 0.1);
+        assertArrayEquals("The seound row is not correct", matrixC[1], result[1], 0.1);
     }
 
     @Test
     public void multiplyTowMatriciesWithDiffrentDimensions() {
         MatrixCalcMath math = new MatrixCalcMath();
-        //A(2,3) B(3,2) => C(2,2)
-        double[][] matrixA = { { 1.0, 1.0, 1.0}, { 1.0, 1.0, 1.0 } };
+        // A(2,3) B(3,2) => C(2,2)
+        double[][] matrixA = { { 1.0, 1.0, 1.0 }, { 1.0, 1.0, 1.0 } };
         double[][] matrixB = { { 1.0, 1.0 }, { 1.0, 1.0 }, { 1.0, 1.0 } };
         double[][] matrixC = { { 3.0, 3.0 }, { 3.0, 3.0 } };
-        assertArrayEquals("The first row is not correct", matrixC[0], math.matrixMultiplication(matrixA, matrixB)[0],
-                0.1);
-        assertArrayEquals("The seound row is not correct", matrixC[1], math.matrixMultiplication(matrixA, matrixB)[1],
-                0.1);
+
+        double[][] result = math.matrixMultiplication(matrixA, matrixB);
+
+        assertArrayEquals("The first row is not correct", matrixC[0], result[0], 0.1);
+        assertArrayEquals("The seound row is not correct", matrixC[1], result[1], 0.1);
     }
 
     @Test
     public void multiplyTowMatriciesWithDiffrentDimensionsAndDiffentContent() {
         MatrixCalcMath math = new MatrixCalcMath();
-        //A(2,3) B(3,2) => C(2,2)
-        double[][] matrixA = { { 1.0, 2.0, 3.0}, { 4.0, 5.0, 6.0 } };
+        // A(2,3) B(3,2) => C(2,2)
+        double[][] matrixA = { { 1.0, 2.0, 3.0 }, { 4.0, 5.0, 6.0 } };
         double[][] matrixB = { { 7.0, 8.0 }, { 9.0, 10.0 }, { 11.0, 12.0 } };
         double[][] matrixC = { { 58.0, 64.0 }, { 139.0, 154.0 } };
-        assertArrayEquals("The first row is not correct", matrixC[0], math.matrixMultiplication(matrixA, matrixB)[0],
-                0.1);
-        assertArrayEquals("The seound row is not correct", matrixC[1], math.matrixMultiplication(matrixA, matrixB)[1],
-                0.1);
+
+        double[][] result = math.matrixMultiplication(matrixA, matrixB);
+
+        assertArrayEquals("The first row is not correct", matrixC[0], result[0], 0.1);
+        assertArrayEquals("The seound row is not correct", matrixC[1], result[1], 0.1);
     }
 
     @Test
     public void tryToMultiplyTowEmptyMatricies() {
         MatrixCalcMath math = new MatrixCalcMath();
-        //A(0,0) B(0,0) => null
+        // A(0,0) B(0,0) => null
         double[][] matrixA = new double[0][0];
         double[][] matrixB = new double[0][0];
-        assertArrayEquals(null, math.matrixAddition(matrixA, matrixB));
+
+        double[][] result = math.matrixMultiplication(matrixA, matrixB);
+
+        assertArrayEquals(null, result);
     }
 
     @Test
     public void tryToMultiplyTowNullObjects() {
         MatrixCalcMath math = new MatrixCalcMath();
-        //null null => null
+        // null null => null
         double[][] matrixA = null;
         double[][] matrixB = null;
-        assertArrayEquals(null, math.matrixAddition(matrixA, matrixB));
+
+        double[][] result = math.matrixMultiplication(matrixA, matrixB);
+
+        assertArrayEquals(null, result);
     }
 }