diff --git a/java-strings/src/main/java/com/baeldung/stringduplicates/RemoveDuplicateFromString.java b/java-strings/src/main/java/com/baeldung/stringduplicates/RemoveDuplicateFromString.java index eeba81f334..d8fd9c4b14 100644 --- a/java-strings/src/main/java/com/baeldung/stringduplicates/RemoveDuplicateFromString.java +++ b/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(); + } + } diff --git a/java-strings/src/test/java/com/baeldung/stringduplicates/RemoveDuplicateFromStringUnitTest.java b/java-strings/src/test/java/com/baeldung/stringduplicates/RemoveDuplicateFromStringUnitTest.java index cf7819ced3..895ecc4a3b 100644 --- a/java-strings/src/test/java/com/baeldung/stringduplicates/RemoveDuplicateFromStringUnitTest.java +++ b/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); + } }