Solving the Kata

src/main/java/org/fundacionjala/coding/abel/DataReverse.java

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+package org.fundacionjala.coding.abel;
+
+import java.util.stream.IntStream;
+
+/**
+ * CA stream of data is received and needs to be reversed. Each segment is 8 bits
+ * meaning the order of these segments need to be reversed:
+ * 11111111 00000000 00001111 10101010
+ * (byte1) (byte2) (byte3) (byte4)
+ * 10101010 00001111 00000000 11111111
+ * (byte4) (byte3) (byte2) (byte1)
+ * Total number of bits will always be a multiple of 8. The data is given in an array as such:
+ * [1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,0,1,0,1,0,1,0]
+ */
+public final class DataReverse {
+
+    /**
+     * Private Constructor.
+     */
+    private DataReverse() {
+
+    }
+
+    /**
+     * Reverse the bytes on the input.
+     *
+     * @param data int[].
+     * @return int[].
+     */
+    public static int[] dataReverse(int[] data) {
+        int numberOfBytes = (data.length / 8) - 1;
+        int[] result = new int[data.length];
+        IntStream.rangeClosed(0, numberOfBytes)
+                .forEach(i -> {
+                    int dataPosition = 8 * i;
+                    int resultPosition = (8 * numberOfBytes) - dataPosition;
+                    IntStream.range(0, 8)
+                            .forEach(n -> {
+                                result[n + resultPosition] = data[n + dataPosition];
+                            });
+                });
+
+        return result;
+    }
+}

src/test/java/org/fundacionjala/coding/abel/DataReverseTest.java

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+package org.fundacionjala.coding.abel;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Modifier;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertTrue;
+
+/**
+ * Test for DataReverse Kata.
+ */
+public class DataReverseTest {
+
+    /**
+     * Test for Private Constructors.
+     *
+     * @throws NoSuchMethodException     Thrown when a particular method cannot be found.
+     * @throws IllegalAccessException    Thrown when an application tries to reflectively create an instance.
+     * @throws InvocationTargetException thrown by an invoked method or constructor.
+     * @throws InstantiationException    Thrown when an application tries to create an instance of a class
+     *                                   using the {@code newInstance} method in class.
+     */
+    @Test
+    public void privateConstructorTest() throws NoSuchMethodException, IllegalAccessException,
+            InvocationTargetException, InstantiationException {
+        Constructor<DataReverse> constructor = DataReverse.class.getDeclaredConstructor();
+        assertTrue(Modifier.isPrivate(constructor.getModifiers()));
+        constructor.setAccessible(true);
+        constructor.newInstance();
+    }
+
+    /**
+     * First tests.
+     */
+    @Test
+    public void testOne() {
+        int[] data1 = {1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 0, 1, 0};
+        int[] data2 = {1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1};
+        assertArrayEquals(data2, DataReverse.dataReverse(data1));
+    }
+
+    /**
+     * Second tests.
+     */
+    @Test
+    public void testTwo() {
+        int[] data1 = {0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 1, 0, 1, 0, 0, 1};
+        int[] data2 = {0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0};
+        assertArrayEquals(data2, DataReverse.dataReverse(data1));
+
+    }
+}