Objects, immutability and switch expressions

AnghelLeonard · AnghelLeonard · commit b9dd14638780 · 2020-04-21T08:46:04.000+03:00
diff --git a/Chapter02/P53_CloningObjects/src/main/java/modern/challenge/Main.java b/Chapter02/P53_CloningObjects/src/main/java/modern/challenge/Main.java
@@ -7,14 +7,16 @@
 import java.io.IOException;
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
+import java.util.Arrays;
+import modern.challenge.shallow.copy.matrix.Matrices;
 import org.apache.commons.lang3.SerializationUtils;
 
 public class Main {
 
     public static void main(String[] args) throws CloneNotSupportedException {
 
         // shallow copy via manual copy
-        System.out.println("Shallow copy via manual copy:");
+        System.out.println("\nShallow copy via manual copy:");
         modern.challenge.shallow.copy.manually.Point point1
                 = new modern.challenge.shallow.copy.manually.Point(5, 5);
 
@@ -159,6 +161,44 @@ public static void main(String[] args) throws CloneNotSupportedException {
         System.out.println("Clone 7, (x, y, Radius start, Radius end): "
                 + clone7.getX() + ", " + clone7.getY()
                 + ", " + clone7.getRadius().getStart() + ", " + clone7.getRadius().getEnd());
+
+        int[][] source = {{3, 1, 5}, {3, 6, 7}};
+
+        // shallow copy of matrix (1)
+        System.out.println("\nShallow copy of matrix via manual copy (1):");
+        int[][] target1 = Matrices.cloneArrayOfInt1(source);
+        target1[0][0] = 0;
+        System.out.println("Original array:");
+        printMatrix(source);
+        System.out.println("Cloned and modified array:");
+        printMatrix(target1);
+
+        // shallow copy of matrix (2)
+        System.out.println("\nShallow copy of matrix via manual copy (2):");
+        int[][] target2 = Matrices.cloneArrayOfInt2(source);
+        target2[0][0] = 0;
+        System.out.println("Original array:");
+        printMatrix(source);
+        System.out.println("Cloned and modified array:");
+        printMatrix(target2);
+
+        // shallow copy of matrix (3)
+        System.out.println("\nShallow copy of matrix via manual copy (3):");
+        int[][] target3 = Matrices.cloneArrayOfInt3(source);
+        target3[0][0] = 0;
+        System.out.println("Original array:");
+        printMatrix(source);
+        System.out.println("Cloned and modified array:");
+        printMatrix(target3);
+
+        // shallow copy of matrix (4)
+        System.out.println("\nShallow copy of matrix via manual copy (4):");
+        int[][] target4 = Matrices.cloneArrayOfInt4(source);
+        target4[0][0] = 0;
+        System.out.println("Original array:");
+        printMatrix(source);
+        System.out.println("Cloned and modified array:");
+        printMatrix(target4);
     }
 
     @SuppressWarnings("unchecked")
@@ -182,4 +222,14 @@ private static <T> T cloneThroughSerialization(T t) {
             return t;
         }
     }
+
+    // helper method to display a matrix
+    private static void printMatrix(int[][] matrix) {
+        for (int i = 0; i < matrix.length; i++) {
+            for (int j = 0; j < matrix[0].length; j++) {
+                System.out.print(matrix[i][j] + " ");
+            }
+            System.out.println();
+        }
+    }
 }
diff --git a/Chapter02/P53_CloningObjects/src/main/java/modern/challenge/shallow/copy/matrix/Matrices.java b/Chapter02/P53_CloningObjects/src/main/java/modern/challenge/shallow/copy/matrix/Matrices.java
@@ -0,0 +1,61 @@
+package modern.challenge.shallow.copy.matrix;
+
+import java.util.Arrays;
+
+public final class Matrices {
+
+    private Matrices() {
+        throw new AssertionError("Cannot be instantiated");
+    }
+
+    public static int[][] cloneArrayOfInt1(int[][] source) {
+
+        if (source == null) {
+            throw new IllegalArgumentException("The given array cannot be null");
+        }
+
+        int length = source.length;
+        int[][] target = new int[length][source[0].length];
+
+        for (int i = 0; i < length; i++) {
+            target[i] = source[i].clone();
+        }
+
+        return target;
+    }
+
+    public static int[][] cloneArrayOfInt2(int[][] source) {
+
+        if (source == null) {
+            throw new IllegalArgumentException("The given array cannot be null");
+        }
+
+        int length = source.length;
+        int[][] target = new int[length][source[0].length];
+        for (int i = 0; i < length; i++) {
+            System.arraycopy(source[i], 0, target[i], 0, source[i].length);
+        }
+        return target;
+    }
+
+    public static int[][] cloneArrayOfInt3(int[][] source) {
+
+        if (source == null) {
+            throw new IllegalArgumentException("The given array cannot be null");
+        }
+
+        int length = source.length;
+        int[][] target = new int[length][];
+        for (int i = 0; i < length; i++) {
+            target[i] = Arrays.copyOf(source[i], source[i].length);
+        }
+        return target;
+    }
+
+    public static int[][] cloneArrayOfInt4(int[][] source) {
+        return Arrays.stream(source)
+                .map(int[]::clone)
+                .toArray(int[][]::new);
+    }
+
+}
