BAEL-2330 (#5694)

* 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

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

@@ -0,0 +1,95 @@
+package com.baeldung.stringduplicates;
+
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.LinkedHashSet;
+import java.util.Set;
+
+public class RemoveDuplicateFromString {
+
+
+    String removeDuplicatesUsingCharArray(String str) {
+
+        char[] chars = str.toCharArray();
+        StringBuilder sb = new StringBuilder();
+        int repeatedCtr;
+        for (int i = 0; i < chars.length; i++) {
+            repeatedCtr = 0;
+            for (int j = i + 1; j < chars.length; j++) {
+                if (chars[i] == chars[j]) {
+                    repeatedCtr++;
+                }
+            }
+            if (repeatedCtr == 0) {
+                sb.append(chars[i]);
+            }
+        }
+        return sb.toString();
+    }
+
+    String removeDuplicatesUsinglinkedHashSet(String str) {
+
+        StringBuilder sb = new StringBuilder();
+        Set<Character> linkedHashSet = new LinkedHashSet<>();
+
+        for (int i = 0; i < str.length(); i++) {
+            linkedHashSet.add(str.charAt(i));
+        }
+
+        for (Character c : linkedHashSet) {
+            sb.append(c);
+        }
+
+        return sb.toString();
+    }
+
+    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]);
+            }
+        }
+
+        return sb.toString();
+    }
+
+    String removeDuplicatesUsingHashSet(String str) {
+
+        StringBuilder sb = new StringBuilder();
+        Set<Character> hashSet = new HashSet<>();
+
+        for (int i = 0; i < str.length(); i++) {
+            hashSet.add(str.charAt(i));
+        }
+
+        for (Character c : hashSet) {
+            sb.append(c);
+        }
+
+        return sb.toString();
+    }
+
+    String removeDuplicatesUsingIndexOf(String str) {
+
+        StringBuilder sb = new StringBuilder();
+        int idx;
+        for (int i = 0; i < str.length(); i++) {
+            char c = str.charAt(i);
+            idx = str.indexOf(c, i + 1);
+            if (idx == -1) {
+                sb.append(c);
+            }
+        }
+        return sb.toString();
+    }
+
+}
+
+

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

@@ -0,0 +1,58 @@
+package com.baeldung.stringduplicates;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+public class RemoveDuplicateFromStringUnitTest {
+
+    private final static String STR1 = "racecar";
+    private final static String STR2 = "J2ee programming";
+    private RemoveDuplicateFromString removeDuplicateFromString;
+
+    @Before
+    public void executedBeforeEach() {
+        removeDuplicateFromString = new RemoveDuplicateFromString();
+    }
+
+
+    @Test
+    public void whenUsingCharArray_DuplicatesShouldBeRemovedWithoutKeepingStringOrder() {
+        String str1 = removeDuplicateFromString.removeDuplicatesUsingCharArray(STR1);
+        String str2 = removeDuplicateFromString.removeDuplicatesUsingCharArray(STR2);
+        Assert.assertEquals("ecar", str1);
+        Assert.assertEquals("J2e poraming", str2);
+    }
+
+    @Test
+    public void whenUsingLinkedHashSet_DuplicatesShouldBeRemovedAndItKeepStringOrder() {
+        String str1 = removeDuplicateFromString.removeDuplicatesUsinglinkedHashSet(STR1);
+        String str2 = removeDuplicateFromString.removeDuplicatesUsinglinkedHashSet(STR2);
+        Assert.assertEquals("race", str1);
+        Assert.assertEquals("J2e progamin", str2);
+    }
+
+    @Test
+    public void whenUsingSorting_DuplicatesShouldBeRemovedWithoutKeepingStringOrder() {
+        String str1 = removeDuplicateFromString.removeDuplicatesUsingSorting(STR1);
+        String str2 = removeDuplicateFromString.removeDuplicatesUsingSorting(STR2);
+        Assert.assertEquals("acer", str1);
+        Assert.assertEquals(" 2Jaegimnopr", str2);
+    }
+
+    @Test
+    public void whenUsingHashSet_DuplicatesShouldBeRemovedWithoutKeepingStringOrder() {
+        String str1 = removeDuplicateFromString.removeDuplicatesUsingHashSet(STR1);
+        String str2 = removeDuplicateFromString.removeDuplicatesUsingHashSet(STR2);
+        Assert.assertEquals("arce", str1);
+        Assert.assertEquals(" pa2regiJmno", str2);
+    }
+
+    @Test
+    public void whenUsingIndexOf_DuplicatesShouldBeRemovedWithoutKeepingStringOrder() {
+        String str1 = removeDuplicateFromString.removeDuplicatesUsingIndexOf(STR1);
+        String str2 = removeDuplicateFromString.removeDuplicatesUsingIndexOf(STR2);
+        Assert.assertEquals("ecar", str1);
+        Assert.assertEquals("J2e poraming", str2);
+    }
+}