String to matrix Method functional to parse 2by2 matrices

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

@@ -1,5 +1,7 @@
 package com.ugsbo.matrixcalc;
 
+import java.util.ArrayList;
+
 /**
  * Contains all basic matrix math calculations.
  */
@@ -226,4 +228,29 @@ public class MatrixCalcMath {
         return false;
     }
 
+    public double[][] stringToMatrix(String stringMatrix) {
+        
+        ArrayList<String[]> singleNumbersArr =  new ArrayList<String[]>();
+        
+        //Splitting the strings into thier rows
+        String[] singleNumbers = null;
+        String[] rows = stringMatrix.split("\n");
+        for (int i = 0; i < rows.length; i++) {
+            System.out.println(rows[i]);
+            singleNumbers = rows[i].split("\\s");
+            singleNumbersArr.add(singleNumbers);
+        }
+
+        int rowCount = rows.length; //row.length
+        int columCount = singleNumbersArr.size(); //output.length
+        double[][] result = new double[columCount][rowCount];
+        
+        for (int columIndex = 0; columIndex < singleNumbersArr.size(); columIndex++) {
+            for (int rowIndex = 0;  rowIndex < singleNumbers.length; rowIndex++) {
+                    result[columIndex][rowIndex] = Double.parseDouble(singleNumbersArr.get(columIndex)[rowIndex]);
+            }
+        }
+        return result;
+    }
+
 }

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

@@ -0,0 +1,41 @@
+package com.ugsbo.matrixcalc;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Before;
+import org.junit.Test;
+
+/**
+ * Tests the funktionality to Calculate the Determinant of a Matrix.
+ */
+public class StringToMatrixTest {
+
+    private MatrixCalcMath matrixMath;
+
+    @Before
+    public void setup() {
+        matrixMath = new MatrixCalcMath();
+    }
+
+    @Test
+    public void StringWithSingleDigitNumbersToMatrix_ReturnsEquivalentMatrix() {
+        String inputString = "1";
+        double[][] expected = { { 1.0 } };
+        
+        double[][] result = matrixMath.stringToMatrix(inputString);
+
+        assertArrayEquals("The first row is not correct", expected[0], result[0], 0.1);
+    }
+
+    @Test
+    public void StringWithfourDigitNumbersToMatrix_ReturnsEquivalentMatrix() {
+        String inputString = "1 2\n3 4";
+        double[][] expected = { { 1.0, 2.0 }, {3.0, 4.0} };
+        
+        double[][] result = matrixMath.stringToMatrix(inputString);
+
+        assertArrayEquals("The first row is not correct", expected[0], result[0], 0.1);
+        assertArrayEquals("The first row is not correct", expected[1], result[1], 0.1);
+    }
+}