[JAVA-616] core-java-arrays-multidimensional

* Creation

* Moved code from https://www.baeldung.com/java-jagged-arrays

* Moved code from https://www.baeldung.com/java-loop-diagonal-array

core-java-modules/core-java-arrays-2/README.md

@@ -5,7 +5,6 @@ This module contains articles about Java arrays
 ## Relevant Articles
 
 - [Extending an Array’s Length](https://www.baeldung.com/java-array-add-element-at-the-end)
-- [Looping Diagonally Through a 2d Java Array](https://www.baeldung.com/java-loop-diagonal-array)
 - [Converting Between Stream and Array in Java](https://www.baeldung.com/java-stream-to-array)
 - [Convert a Float to a Byte Array in Java](https://www.baeldung.com/java-convert-float-to-byte-array)
 - [Array Operations in Java](https://www.baeldung.com/java-common-array-operations)

core-java-modules/core-java-arrays-2/src/main/java/com/baeldung/array/looping/LoopDiagonally.java

@@ -1,45 +0,0 @@
-package com.baeldung.array.looping;
-
-public class LoopDiagonally {
-
-
-    public String loopDiagonally(String[][] twoDArray) {
-
-        int length = twoDArray.length;
-        int diagonalLines = (length + length) - 1;
-        int itemsInDiagonal = 0;
-        int midPoint = (diagonalLines / 2) + 1;
-        StringBuilder output = new StringBuilder();
-
-        for (int i = 1; i <= diagonalLines; i++) {
-
-            StringBuilder items = new StringBuilder();
-            int rowIndex;
-            int columnIndex;
-
-            if (i <= midPoint) {
-                itemsInDiagonal++;
-                for (int j = 0; j < itemsInDiagonal; j++) {
-                    rowIndex = (i - j) - 1;
-                    columnIndex = j;
-                    items.append(twoDArray[rowIndex][columnIndex]);
-                }
-            } else {
-                itemsInDiagonal--;
-                for (int j = 0; j < itemsInDiagonal; j++) {
-                    rowIndex = (length - 1) - j;
-                    columnIndex = (i - length) + j;
-                    items.append(twoDArray[rowIndex][columnIndex]);
-                }
-            }
-
-            if (i != diagonalLines) {
-                output.append(items).append(" ");
-            } else {
-                output.append(items);
-            }
-        }
-
-        return output.toString();
-    }
-}

core-java-modules/core-java-arrays-2/src/test/java/com/baeldung/array/looping/LoopDiagonallyUnitTest.java

@@ -1,20 +0,0 @@
-package com.baeldung.array.looping;
-
-import org.junit.Test;
-
-import static org.junit.Assert.assertEquals;
-
-public class LoopDiagonallyUnitTest {
-
-    @Test
-    public void twoArrayIsLoopedDiagonallyAsExpected() {
-
-        LoopDiagonally loopDiagonally = new LoopDiagonally();
-        String[][] twoDArray = {{"a", "b", "c"},
-                                {"d", "e", "f"},
-                                {"g", "h", "i"}};
-
-        String output = loopDiagonally.loopDiagonally(twoDArray);
-        assertEquals("a db gec hf i", output);
-    }
-}