BAEL 2330

* Implementing Hexagonal Architecture in java

* Removing duplicates from a string

* Fix for the code review feedback
- removing the hexagonal architecture code
- removing the methods removeDuplicatesUsingCharArray
- adding some meaningful sentences to test

* Fix for the code review feedback
- fix for removeDuplicatesUsingCharArray
- adding unit testing
- adding brackets around for loops

* Fix for the code review feedback

* Adding remove duplicates using java 8 distinct
adding assets to the unittests to test for empty strings

* Checking for empty strings in unit tests
Adding an if statement to check whether an empty string is passed to removeDuplicatesUsingSorting method

java-strings/src/main/java/com/baeldung/stringduplicates/RemoveDuplicateFromString.java

@@ -44,16 +44,16 @@ public class RemoveDuplicateFromString {
     }
 
     String removeDuplicatesUsingSorting(String str) {
-
-        char[] chars = str.toCharArray();
-
-        Arrays.sort(chars);
-
         StringBuilder sb = new StringBuilder();
-        sb.append(chars[0]);
-        for (int i = 1; i < chars.length; i++) {
-            if (chars[i] != chars[i - 1]) {
-                sb.append(chars[i]);
+        if(!str.isEmpty()) {
+            char[] chars = str.toCharArray();
+            Arrays.sort(chars);
+
+            sb.append(chars[0]);
+            for (int i = 1; i < chars.length; i++) {
+                if (chars[i] != chars[i - 1]) {
+                    sb.append(chars[i]);
+                }
             }
         }
 
@@ -90,6 +90,13 @@ public class RemoveDuplicateFromString {
         return sb.toString();
     }
 
+
+    String removeDuplicatesUsingDistinct(String str) {
+        StringBuilder sb = new StringBuilder();
+        str.chars().distinct().forEach(c -> sb.append((char) c));
+        return sb.toString();
+    }
+
 }
 
 

java-strings/src/test/java/com/baeldung/stringduplicates/RemoveDuplicateFromStringUnitTest.java

@@ -8,6 +8,8 @@ public class RemoveDuplicateFromStringUnitTest {
 
     private final static String STR1 = "racecar";
     private final static String STR2 = "J2ee programming";
+    private final static String STR_EMPTY = "";
+
     private RemoveDuplicateFromString removeDuplicateFromString;
 
     @Before
@@ -20,6 +22,8 @@ public class RemoveDuplicateFromStringUnitTest {
     public void whenUsingCharArray_DuplicatesShouldBeRemovedWithoutKeepingStringOrder() {
         String str1 = removeDuplicateFromString.removeDuplicatesUsingCharArray(STR1);
         String str2 = removeDuplicateFromString.removeDuplicatesUsingCharArray(STR2);
+        String strEmpty = removeDuplicateFromString.removeDuplicatesUsingCharArray(STR_EMPTY);
+        Assert.assertEquals("", strEmpty);
         Assert.assertEquals("ecar", str1);
         Assert.assertEquals("J2e poraming", str2);
     }
@@ -28,6 +32,9 @@ public class RemoveDuplicateFromStringUnitTest {
     public void whenUsingLinkedHashSet_DuplicatesShouldBeRemovedAndItKeepStringOrder() {
         String str1 = removeDuplicateFromString.removeDuplicatesUsinglinkedHashSet(STR1);
         String str2 = removeDuplicateFromString.removeDuplicatesUsinglinkedHashSet(STR2);
+
+        String strEmpty = removeDuplicateFromString.removeDuplicatesUsinglinkedHashSet(STR_EMPTY);
+        Assert.assertEquals("", strEmpty);
         Assert.assertEquals("race", str1);
         Assert.assertEquals("J2e progamin", str2);
     }
@@ -36,6 +43,9 @@ public class RemoveDuplicateFromStringUnitTest {
     public void whenUsingSorting_DuplicatesShouldBeRemovedWithoutKeepingStringOrder() {
         String str1 = removeDuplicateFromString.removeDuplicatesUsingSorting(STR1);
         String str2 = removeDuplicateFromString.removeDuplicatesUsingSorting(STR2);
+
+        String strEmpty = removeDuplicateFromString.removeDuplicatesUsingSorting(STR_EMPTY);
+        Assert.assertEquals("", strEmpty);
         Assert.assertEquals("acer", str1);
         Assert.assertEquals(" 2Jaegimnopr", str2);
     }
@@ -44,6 +54,8 @@ public class RemoveDuplicateFromStringUnitTest {
     public void whenUsingHashSet_DuplicatesShouldBeRemovedWithoutKeepingStringOrder() {
         String str1 = removeDuplicateFromString.removeDuplicatesUsingHashSet(STR1);
         String str2 = removeDuplicateFromString.removeDuplicatesUsingHashSet(STR2);
+        String strEmpty = removeDuplicateFromString.removeDuplicatesUsingHashSet(STR_EMPTY);
+        Assert.assertEquals("", strEmpty);
         Assert.assertEquals("arce", str1);
         Assert.assertEquals(" pa2regiJmno", str2);
     }
@@ -52,7 +64,19 @@ public class RemoveDuplicateFromStringUnitTest {
     public void whenUsingIndexOf_DuplicatesShouldBeRemovedWithoutKeepingStringOrder() {
         String str1 = removeDuplicateFromString.removeDuplicatesUsingIndexOf(STR1);
         String str2 = removeDuplicateFromString.removeDuplicatesUsingIndexOf(STR2);
+        String strEmpty = removeDuplicateFromString.removeDuplicatesUsingIndexOf(STR_EMPTY);
+        Assert.assertEquals("", strEmpty);
         Assert.assertEquals("ecar", str1);
         Assert.assertEquals("J2e poraming", str2);
     }
+
+    @Test
+    public void whenUsingJava8_DuplicatesShouldBeRemovedAndItKeepStringOrder() {
+        String str1 = removeDuplicateFromString.removeDuplicatesUsingDistinct(STR1);
+        String str2 = removeDuplicateFromString.removeDuplicatesUsingDistinct(STR2);
+        String strEmpty = removeDuplicateFromString.removeDuplicatesUsingDistinct(STR_EMPTY);
+        Assert.assertEquals("", strEmpty);
+        Assert.assertEquals("race", str1);
+        Assert.assertEquals("J2e progamin", str2);
+    }
 }