diff --git a/java-strings/src/main/java/com/baeldung/stringduplicates/RemoveDuplicateFromString.java b/java-strings/src/main/java/com/baeldung/stringduplicates/RemoveDuplicateFromString.java new file mode 100644 index 0000000000..eeba81f334 --- /dev/null +++ b/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 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 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(); + } + +} + + diff --git a/java-strings/src/test/java/com/baeldung/stringduplicates/RemoveDuplicateFromStringUnitTest.java b/java-strings/src/test/java/com/baeldung/stringduplicates/RemoveDuplicateFromStringUnitTest.java new file mode 100644 index 0000000000..cf7819ced3 --- /dev/null +++ b/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); + } +}