Added solution for Reverse string in place

Author: plaidshirtakos

Reverse string in place/solution.java

@@ -0,0 +1,74 @@
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * Java Program to reverse a String in place, 
+ * without any additional buffer in Java.
+ *
+ * @author WINDOWS 8
+ *
+ */
+public class StringReversal {
+
+    /**
+     * Java method to reverse a String in place
+     * @param str 
+     * @return  reverse of String
+     */
+    public static String reverse(String str) {
+        if(str == null || str.isEmpty()){
+            return str;
+        }
+        char[] characters = str.toCharArray();
+        int i = 0;
+        int j = characters.length - 1;
+        while (i < j) {
+            swap(characters, i, j);
+            i++;
+            j--;
+        }
+        return new String(characters);
+    }
+
+    /**
+     * Java method to swap two numbers in given array
+     * @param str
+     * @param i
+     * @param j 
+     */
+    private static void swap(char[] str, int i, int j) {
+        char temp = str[i];
+        str[i] = str[j];
+        str[j] = temp;
+    }
+
+    @Test
+    public void reverseEmptyString(){
+        Assert.assertEquals("", reverse(""));
+    }
+    
+    @Test
+    public void reverseString(){
+        Assert.assertEquals("cba", reverse("abc"));
+    }
+    
+    @Test
+    public void reverseNullString(){
+        Assert.assertEquals(null, reverse(null));
+    }
+    
+    @Test
+    public void reversePalindromeString(){
+        Assert.assertEquals("aba", reverse("aba"));
+    }
+    
+    @Test
+    public void reverseSameCharacterString(){
+        Assert.assertEquals("aaa", reverse("aaa"));
+    }
+    
+    @Test
+    public void reverseAnagramString(){
+        Assert.assertEquals("mary", reverse("yram"));
+    }
+}