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BAEL-6710 (#14403) 

Check If a String Has All Unique Characters in Java
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parthiv39731 2023-07-14 01:19:18 +05:30 committed by GitHub
parent 8be07c6b36
commit c93173406e
2 changed files with 152 additions and 0 deletions
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60
core-java-modules/core-java-string-operations-6/src/main/java/com/baeldung/uniquecharcheck/UniqueCharChecker.java Normal file
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package com.baeldung.uniquecharcheck;
import org.apache.commons.lang3.StringUtils;
import java.util.*;
import java.util.stream.Collectors;
public class UniqueCharChecker {
public static boolean checkV1(String str) {
char[] chars = str.toUpperCase().toCharArray();
for (int i = 0; i < chars.length; i++) {
for (int j = i + 1; j < chars.length; j++) {
if(chars[i] == chars[j]) {
return false;
}
}
}
return true;
}
public static boolean checkV2(String str) {
char[] chars = str.toUpperCase().toCharArray();
Arrays.sort(chars);
for (int i = 0; i < chars.length - 1; i++) {
if(chars[i] == chars[i+1]) {
return false;
}
}
return true;
}
public static boolean checkV3(String str) {
char[] chars = str.toUpperCase().toCharArray();
Set <Character> set = new HashSet <>();
for (char c: chars) {
set.add(c);
}
return set.size() == str.length();
}
public static boolean checkV4(String str) {
boolean isUnique = str.toUpperCase().chars()
.mapToObj(c -> (char)c)
.collect(Collectors.toSet())
.size() == str.length();
return isUnique;
}
public static boolean checkV5(String str) {
for (int i = 0; i < str.length(); i++) {
String curChar = String.valueOf(str.charAt(i));
String remainingStr = str.substring(i+1);
if(StringUtils.containsIgnoreCase(remainingStr, curChar)) {
return false;
}
}
return true;
}
}

92
core-java-modules/core-java-string-operations-6/src/test/java/com/baeldung/uniquecharcheck/UniqueCharCheckerUnitTest.java Normal file
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package com.baeldung.uniquecharcheck;
import org.junit.Test;
import java.util.Arrays;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
public class UniqueCharCheckerUnitTest {
@Test
public void givenMethCheck1_whenUnique_returnTrue() {
String[] sampleStrings = new String[]{"Justfewdi123", "$%&Hibusc", "Hibusc%$#", "მშვნიერ"};
final String MSG = "Duplicate found";
Arrays.stream(sampleStrings)
.forEach(sampleStr -> assertTrue(MSG + " in " + sampleStr, UniqueCharChecker.checkV1(sampleStr)));
}
@Test
public void givenMethCheck2_whenUnique_returnTrue() {
String[] sampleStrings = new String[]{"Justfewdi123", "$%&Hibusc", "Hibusc%$#", "მშვნიერ"};
final String MSG = "Duplicate found";
Arrays.stream(sampleStrings)
.forEach(sampleStr -> assertTrue(MSG + " in " + sampleStr, UniqueCharChecker.checkV2(sampleStr)));
}
@Test
public void givenMethCheck3_whenUnique_returnTrue() {
String[] sampleStrings = new String[]{"Justfewdi123", "$%&Hibusc", "Hibusc%$#", "მშვნიერ"};
final String MSG = "Duplicate found";
Arrays.stream(sampleStrings)
.forEach(sampleStr -> assertTrue(MSG + " in " + sampleStr, UniqueCharChecker.checkV3(sampleStr)));
}
@Test
public void givenMethCheck4_whenUnique_returnTrue() {
String[] sampleStrings = new String[]{"Justfewdi123", "$%&Hibusc", "Hibusc%$#", "მშვნიერ"};
final String MSG = "Duplicate found";
Arrays.stream(sampleStrings)
.forEach(sampleStr -> assertTrue(MSG + " in " + sampleStr, UniqueCharChecker.checkV1(sampleStr)));
}
@Test
public void givenMethCheck5_whenUnique_returnTrue() {
String[] sampleStrings = new String[]{"Justfewdi123", "$%&Hibusc", "Hibusc%$#", "მშვნიერ"};
final String MSG = "Duplicate found";
Arrays.stream(sampleStrings)
.forEach(sampleStr -> assertTrue(MSG + " in " + sampleStr, UniqueCharChecker.checkV5(sampleStr)));
}
@Test
public void givenMethCheck1_whenNotUnique_returnFalse() {
String[] sampleStrings = new String[]{"Justfewdif123", "$%&Hibushc", "Hibusuc%$#", "Hi%busc%$#", "მშვენიერი"};
final String MSG = "Duplicate not found";
Arrays.stream(sampleStrings)
.forEach(sampleStr -> assertFalse(MSG + " in " + sampleStr, UniqueCharChecker.checkV1(sampleStr)));
}
@Test
public void givenMethCheck2_whenNotUnique_returnFalse() {
String[] sampleStrings = new String[]{"Justfewdif123", "$%&Hibushc", "Hibusuc%$#", "Hi%busc%$#", "მშვენიერი"};
final String MSG = "Duplicate not found";
Arrays.stream(sampleStrings)
.forEach(sampleStr -> assertFalse(MSG + " in " + sampleStr, UniqueCharChecker.checkV2(sampleStr)));
}
@Test
public void givenMethCheck3_whenNotUnique_returnFalse() {
String[] sampleStrings = new String[]{"Justfewdif123", "$%&Hibushc", "Hibusuc%$#", "Hi%busc%$#", "მშვენიერი"};
final String MSG = "Duplicate not found";
Arrays.stream(sampleStrings)
.forEach(sampleStr -> assertFalse(MSG + " in " + sampleStr, UniqueCharChecker.checkV3(sampleStr)));
}
@Test
public void givenMethCheck4_whenNotUnique_returnFalse() {
String[] sampleStrings = new String[]{"Justfewdif123", "$%&Hibushc", "Hibusuc%$#", "Hi%busc%$#", "მშვენიერი"};
final String MSG = "Duplicate not found";
Arrays.stream(sampleStrings)
.forEach(sampleStr -> assertFalse(MSG + " in " + sampleStr, UniqueCharChecker.checkV4(sampleStr)));
}
@Test
public void givenMethCheck5_whenNotUnique_returnFalse() {
String[] sampleStrings = new String[]{"Justfewdif123", "$%&Hibushc", "Hibusuc%$#", "Hi%busc%$#", "მშვენიერი"};
final String MSG = "Duplicate not found";
Arrays.stream(sampleStrings)
.forEach(sampleStr -> assertFalse(MSG + " in " + sampleStr, UniqueCharChecker.checkV5(sampleStr)));
}
}