[Java] 문자가 숫자인지 문자인지 판단하기 (Character.isDigit(), Character.isLetter())

📍알고리즘 문제를 풀다가, 유용하게 쓴 메서드를 잊지 않으려고 포스팅 해본다.

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📎 문자가 숫자인지 판단

• 아래의 설명을 참조하면 '1' ~ '9' 까지의 숫자가 들어오면 true가 반환된다는 것을 알 수 있다.

/*
Determines if the specified character is a digit.
A character is a digit if its general category type, provided by Character.getType(ch), is DECIMAL_DIGIT_NUMBER.
Some Unicode character ranges that contain digits:
'\u0030' through '\u0039', ISO-LATIN-1 digits ('0' through '9')
'\u0660' through '\u0669', Arabic-Indic digits
'\u06F0' through '\u06F9', Extended Arabic-Indic digits
'\u0966' through '\u096F', Devanagari digits
'\uFF10' through '\uFF19', Fullwidth digits
Many other character ranges contain digits as well.
Note: This method cannot handle supplementary characters. To support all Unicode characters, including supplementary characters, use the isDigit(int) method.

매개변수:
ch – the character to be tested.

반환:
true if the character is a digit; false otherwise.
*/

public static boolean isDigit(char ch) {
    return isDigit((int)ch);
}

 

📎 문자가 문자인지 판단

• 아래의 설명을 참조하면 대문자, 소문자 등의 문자가 들어오면 true가 반환됨을 알 수 있다.

/*
Determines if the specified character is a letter.
A character is considered to be a letter if its general category type, provided by Character.getType(ch), is any of the following:
  • UPPERCASE_LETTER
  • LOWERCASE_LETTER
  • TITLECASE_LETTER
  • MODIFIER_LETTER
  • OTHER_LETTER
Not all letters have case. Many characters are letters but are neither uppercase nor lowercase nor titlecase.
Note: This method cannot handle supplementary characters. To support all Unicode characters, including supplementary characters, use the isLetter(int) method.

매개변수:
ch – the character to be tested.

반환:
true if the character is a letter; false otherwise.
*/

public static boolean isLetter(char ch) {
    return isLetter((int)ch);
}

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❄️ 출력 예시

public class CheckCharacter {
   public static void main(String[] args) {
      System.out.println(Character.isDigit('7'));
      System.out.println(Character.isLetter('가'));
   }
}

 

 

 

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