What's the best way to check if a character is a vowel in Java?
Question
I'm trying to check if a certain char is a vowel. What's the best way to go about doing this?
5 answers
solution1
8 ACCPTED 2014-10-24 23:14:49
Here's the solution I've been using for a while, and it hasn't let me down yet:
private static String VOWELS = "AÀÁÂÃÄÅĀĂĄǺȀȂẠẢẤẦẨẪẬẮẰẲẴẶḀÆǼEȄȆḔḖḘḚḜẸẺẼẾỀỂỄỆĒĔĖĘĚÈÉÊËIȈȊḬḮỈỊĨĪĬĮİÌÍÎÏIJOŒØǾȌȎṌṎṐṒỌỎỐỒỔỖỘỚỜỞỠỢŌÒÓŎŐÔÕÖUŨŪŬŮŰŲÙÚÛÜȔȖṲṴṶṸṺỤỦỨỪỬỮỰYẙỲỴỶỸŶŸÝ";
private static boolean isVowel(char c)
{
return VOWELS.indexOf(Character.toUpperCase(c)) >= 0;
}
For my applications, it's reasonably fast.
solution2
2 2018-07-14 02:10:41
Riffing on the accepted answer, here is a solution that requires at most 2 efficient table lookups:
public static boolean isVowel(char c) {
switch (c) {
case 65:
case 69:
case 73:
case 79:
case 85:
case 89:
case 97:
case 101:
case 105:
case 111:
case 117:
case 121:
case 192:
case 193:
case 194:
case 195:
case 196:
case 197:
case 198:
case 200:
case 201:
case 202:
case 203:
case 204:
case 205:
case 206:
case 207:
case 210:
case 211:
case 212:
case 213:
case 214:
case 216:
case 217:
case 218:
case 219:
case 220:
case 221:
case 224:
case 225:
case 226:
case 227:
case 228:
case 229:
case 230:
case 232:
case 233:
case 234:
case 235:
case 236:
case 237:
case 238:
case 239:
case 242:
case 243:
case 244:
case 245:
case 246:
case 248:
case 249:
case 250:
case 251:
case 252:
case 253:
case 255:
case 256:
case 257:
case 258:
case 259:
case 260:
case 261:
case 274:
case 275:
case 276:
case 277:
case 278:
case 279:
case 280:
case 281:
case 282:
case 283:
case 296:
case 297:
case 298:
case 299:
case 300:
case 301:
case 302:
case 303:
case 304:
case 305:
case 306:
case 307:
case 332:
case 333:
case 334:
case 335:
case 336:
case 337:
case 338:
case 339:
case 360:
case 361:
case 362:
case 363:
case 364:
case 365:
case 366:
case 367:
case 368:
case 369:
case 370:
case 371:
case 374:
case 375:
case 376:
case 506:
case 507:
case 508:
case 509:
case 510:
case 511:
case 512:
case 513:
case 514:
case 515:
case 516:
case 517:
case 518:
case 519:
case 520:
case 521:
case 522:
case 523:
case 524:
case 525:
case 526:
case 527:
case 532:
case 533:
case 534:
case 535:
return true;
default:
switch (c) {
case 7680:
case 7681:
case 7700:
case 7701:
case 7702:
case 7703:
case 7704:
case 7705:
case 7706:
case 7707:
case 7708:
case 7709:
case 7724:
case 7725:
case 7726:
case 7727:
case 7756:
case 7757:
case 7758:
case 7759:
case 7760:
case 7761:
case 7762:
case 7763:
case 7794:
case 7795:
case 7796:
case 7797:
case 7798:
case 7799:
case 7800:
case 7801:
case 7802:
case 7803:
case 7833:
case 7840:
case 7841:
case 7842:
case 7843:
case 7844:
case 7845:
case 7846:
case 7847:
case 7848:
case 7849:
case 7850:
case 7851:
case 7852:
case 7853:
case 7854:
case 7855:
case 7856:
case 7857:
case 7858:
case 7859:
case 7860:
case 7861:
case 7862:
case 7863:
case 7864:
case 7865:
case 7866:
case 7867:
case 7868:
case 7869:
case 7870:
case 7871:
case 7872:
case 7873:
case 7874:
case 7875:
case 7876:
case 7877:
case 7878:
case 7879:
case 7880:
case 7881:
case 7882:
case 7883:
case 7884:
case 7885:
case 7886:
case 7887:
case 7888:
case 7889:
case 7890:
case 7891:
case 7892:
case 7893:
case 7894:
case 7895:
case 7896:
case 7897:
case 7898:
case 7899:
case 7900:
case 7901:
case 7902:
case 7903:
case 7904:
case 7905:
case 7906:
case 7907:
case 7908:
case 7909:
case 7910:
case 7911:
case 7912:
case 7913:
case 7914:
case 7915:
case 7916:
case 7917:
case 7918:
case 7919:
case 7920:
case 7921:
case 7922:
case 7923:
case 7924:
case 7925:
case 7926:
case 7927:
case 7928:
case 7929:
return true;
}
}
return false;
}
The nested switches are necessary to keep the cases dense and generate two constant-time tableswitch instructions. A single switch with a large gap between 535 and 7680 would generate a logarithmic-time lookupswitch instruction instead.
solution3
1 2014-10-24 23:25:50
Create a switch statement. For example:
switch (Character.toLowerCase(foo)) {
case 'a':
case 'e':
case 'i':
case 'o':
case 'u':
case 'y': return true;
default: return false;
}
For Unicode, How do I detect unicode characters in a Java string? follow answer given here then using a switch statement i provided.
solution4
1 2014-10-24 23:34:37
One way to do this is using if-else or switch case like @TylerWeaver's answer. If you want to do this in one line just use regular expressions
Something like this:
For Vowels:
aStr.matches("[aeiou]")
For Consonants:
aStr.matches("[^aeiou]")
Regular expressions make life very simple and is fairly easy to learn, too. Look at this cheatsheet .
In this case you are just creating a range [aeiou] which means your character must match either a or e or i or o or u . [^aeiou] is all characters other than the ones mentioned in the range.
solution5
1 2017-02-20 21:29:04
I've tried to implement this to cover as many languages as have vowel-like letters in them. By my count, there are 637 Unicode letters that would be useful to count as vowels. I have a class for vowels with a static block setting up a HashSet of Strings representing each vowel. I use a method which assumes a codepoint (int) rather than a char:
public class Vowels {
public Vowels() {
}
public static Set<String> vowelStrs;
static {
vowelStrs = new HashSet<String>();
vowelStrs.add("A");
vowelStrs.add("E");
vowelStrs.add("I");
...
vowelStrs.add("\u00c4");
...
vowelStrs.add("\ua66b");
vowelStrs.add("\ua66c");
vowelStrs.add("\ua66d");
}
public boolean isMember(int inChar) {
String inStr = new String(Character.toChars(inChar));
return(Vowels.vowelStrs.contains(inStr));
}
}
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