[英]Better way to generate array of all letters in the alphabet
現在我正在做
for (char c = 'a'; c <= 'z'; c++) {
alphabet[c - 'a'] = c;
}
但是有更好的方法嗎? 類似於 Scala 的'a' to 'z'
我認為這最終會更干凈一些,您不必處理減法和索引:
char[] alphabet = "abcdefghijklmnopqrstuvwxyz".toCharArray();
char[] alphabet = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
此getAlphabet
方法使用與該問題類似的技術來為任意語言生成字母表。
將任何語言定義為枚舉,然后調用getAlphabet
。
char[] armenianAlphabet = getAlphabet(LocaleLanguage.ARMENIAN);
char[] russianAlphabet = getAlphabet(LocaleLanguage.RUSSIAN);
// get uppercase alphabet
char[] currentAlphabet = getAlphabet(true);
System.out.println(armenianAlphabet);
System.out.println(russianAlphabet);
System.out.println(currentAlphabet);
I/System.out:աբգդեզէըթժիլխծկհձղճմյնշոչպջռսվտրցւփքօֆ
I/System.out: абвгдежзийклмнопрстуфхцчшщъыьэюя
I/System.out:ABCDEFGHIJKLMNOPQRSTUVWXYZ
private char[] getAlphabet() {
return getAlphabet(false);
}
private char[] getAlphabet(boolean flagToUpperCase) {
Locale locale = getResources().getConfiguration().locale;
LocaleLanguage language = LocaleLanguage.getLocalLanguage(locale);
return getAlphabet(language, flagToUpperCase);
}
private char[] getAlphabet(LocaleLanguage localeLanguage, boolean flagToUpperCase) {
if (localeLanguage == null)
localeLanguage = LocaleLanguage.ENGLISH;
char firstLetter = localeLanguage.getFirstLetter();
char lastLetter = localeLanguage.getLastLetter();
int alphabetSize = lastLetter - firstLetter + 1;
char[] alphabet = new char[alphabetSize];
for (int index = 0; index < alphabetSize; index++) {
alphabet[index] = (char) (index + firstLetter);
}
if (flagToUpperCase) {
alphabet = new String(alphabet).toUpperCase().toCharArray();
}
return alphabet;
}
private enum LocaleLanguage {
ARMENIAN(new Locale("hy"), 'ա', 'ֆ'),
RUSSIAN(new Locale("ru"), 'а','я'),
ENGLISH(new Locale("en"), 'a','z');
private final Locale mLocale;
private final char mFirstLetter;
private final char mLastLetter;
LocaleLanguage(Locale locale, char firstLetter, char lastLetter) {
this.mLocale = locale;
this.mFirstLetter = firstLetter;
this.mLastLetter = lastLetter;
}
public Locale getLocale() {
return mLocale;
}
public char getFirstLetter() {
return mFirstLetter;
}
public char getLastLetter() {
return mLastLetter;
}
public String getDisplayLanguage() {
return getLocale().getDisplayLanguage();
}
public String getDisplayLanguage(LocaleLanguage locale) {
return getLocale().getDisplayLanguage(locale.getLocale());
}
@Nullable
public static LocaleLanguage getLocalLanguage(Locale locale) {
if (locale == null)
return LocaleLanguage.ENGLISH;
for (LocaleLanguage localeLanguage : LocaleLanguage.values()) {
if (localeLanguage.getLocale().getLanguage().equals(locale.getLanguage()))
return localeLanguage;
}
return null;
}
}
這是一個有趣的 Unicode 解決方案:
int charAmount = 'z' - 'a' + 1;
char[] alpha = new char[charAmount];
for(int i = 0; i < charAmount ; i++){
alpha[i] = (char)('a' + i);
}
System.out.println(alpha); //abcdefghijklmnopqrstuvwxyz
這會生成字母表的小寫版本。
如果要大寫,可以在('a' + i)
處將 'a' 替換為 'A' 。
在帶有 Stream API 的 Java 8 中,您可以執行此操作。
IntStream.rangeClosed('A', 'Z').mapToObj(var -> (char) var).forEach(System.out::println);
如果您使用的是 Java 8
char[] charArray = IntStream.rangeClosed('A', 'Z')
.mapToObj(c -> "" + (char) c).collect(Collectors.joining()).toCharArray();
static String[] AlphabetWithDigits = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z", "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"};
一旦我確定你會得到a
到z
字母,請檢查這個:
for (char c = 'a'; c <= 'z'; c++) {
al.add(c);
}
System.out.println(al);'
使用io.vavr
public static char[] alphanumericAlphabet() {
return CharSeq
.rangeClosed('0','9')
.appendAll(CharSeq.rangeClosed('a','z'))
.appendAll(CharSeq.rangeClosed('A','Z'))
.toCharArray();
}
以下是基於@tom thomas的回答的一些替代方案。
char[] list = IntStream.concat(
IntStream.rangeClosed('0', '9'),
IntStream.rangeClosed('A', 'Z')
).mapToObj(c -> (char) c+"").collect(Collectors.joining()).toCharArray();
注意:如果您的分隔符也是值之一,則無法正常工作。
String[] list = IntStream.concat(
IntStream.rangeClosed('0', '9'),
IntStream.rangeClosed('A', 'Z')
).mapToObj(c -> (char) c+",").collect(Collectors.joining()).split(",");
注意:如果您的分隔符也是值之一,則無法正常工作。
List<String> list = Arrays.asList(IntStream.concat(
IntStream.rangeClosed('0', '9'),
IntStream.rangeClosed('A', 'Z')
).mapToObj(c -> (char) c+",").collect(Collectors.joining()).split(","));
對於搜索 Kotlin 解決方案並在此處結束的 Android 開發人員:
// Creates List<Char>
val chars1 = ('a'..'z').toList()
// Creates Array<Char> (boxed)
val chars2 = ('a'..'z').toList().toTypedArray()
// Creates CharArray (unboxed)
val chars3 = CharArray(26) { 'a' + it }
// Creates CharArray (unboxed)
val chars4 = ('a'..'z').toArray()
fun CharRange.toArray() = CharArray(count()) { 'a' + it }
要了解我所說的“裝箱”和“未裝箱”的意思,請參閱這篇文章。
非常感謝這個 Kotlin 討論線程。
簡單是一種美德。 使用這個自然可讀的數組:
char alphabet[] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};
char[] abc = new char[26];
for(int i = 0; i<26;i++) {
abc[i] = (char)('a'+i);
}
使用 Java 8 流
char [] alphabets = Stream.iterate('a' , x -> (char)(x + 1))
.limit(26)
.map(c -> c.toString())
.reduce("", (u , v) -> u + v).toCharArray();
要獲取除小寫字母之外的大寫字母,您還可以執行以下操作:
String alphabetWithUpper = "abcdefghijklmnopqrstuvwxyz" + "abcdefghijklmnopqrstuvwxyz".toUpperCase();
char[] letters = alphabetWithUpper.toCharArray();
在 kotlin 中你可以這樣做
var alphabet = "abcdefghijklmnopqrstuvwxyz".toCharArray()
var alphabet = IntStream.rangeClosed('a', 'z')
.boxed()
.map(Character::toChars)
.map(String::valueOf)
.toList();
rangeClosed()
以使其包含'z'
boxed()
以便從IntStream
創建一個列表toList()
創建一個不可修改的列表,但顯然僅從Java 16 開始可用現在我在做
for (char c = 'a'; c <= 'z'; c++) {
alphabet[c - 'a'] = c;
}
但是有沒有更好的方法來做到這一點? 類似於 Scala 的'a' to 'z'
import java.util.*;
public class Experiments{
List uptoChar(int i){
char c='a';
List list = new LinkedList();
for(;;) {
list.add(c);
if(list.size()==i){
break;
}
c++;
}
return list;
}
public static void main (String [] args) {
Experiments experiments = new Experiments();
System.out.println(experiments.uptoChar(26));
}
for (char letter = 'a'; letter <= 'z'; letter++)
{
System.out.println(letter);
}
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