[Java] #Formating, 포맷

 

Java Formating

DecimalFormat

• 숫자를 형삭화 하는 사용
• 패턴을 정의하여 사용
• 사용법
• double number = 1234567.89
  DecimalFormat df = new DecimalFormat("###.#"); //소수 첫째자리까지만 표시
  String result = df.format(number); //1234567.9 반올림

• 10진수로 표현 할 떄, 0, #을 사용하는데, 0과 #을 같이 사용 못함.
• IllegalArgumentException 발생
• 통화 표시할 때
• double number = 123456789;
  DecimalFormat df = new DecimalFormat("\u00A4 #,####");
  String result = df.format(number); //₩ 1,2345,6789

Symbol	Location	Meaning
0	Number	Digit
#	Number	Digit, zero shows as absent
.	Number	Decimal separator or monetary decimal separator
-	Number	Minus sign
,	Number	Grouping separator
E	Number	Separates mantissa and exponent in scientific notation. Need not be quoted in prefix or suffix.
;	Subpattern boundary	Separates positive and negative subpatterns
%	Prefix or suffix	Multiply by 100 and show as percentage
\u2030	Prefix or suffix	Multiply by 1000 and show as per mille value
¤(\u00A4)	Prefix or suffix	Currency sign, replaced by currency symbol. If doubled, replaced by international currency symbol. If present in a pattern, the monetary decimal separator is used instead of the decimal separator.
'	Prefix or suffix	Used to quote special characters in a prefix or suffix, for example, "'#'#" formats 123 to"#123". To create a single quote itself, use two in a row: "# o''clock".

SimpleDateFormat

• 날짜 데이터를 원하는 형태로 출력 할 때

Letter	Date or Time Component	Presentation	Examples
G	Era designator	Text	AD
y	Year	Year	1996; 96
Y	Week year	Year	2009; 09
M	Month in year	Month	July; Jul; 07
w	Week in year	Number	27
W	Week in month	Number	2
D	Day in year	Number	189
d	Day in month	Number	10
F	Day of week in month	Number	2
E	Day name in week	Text	Tuesday; Tue
u	Day number of week (1 = Monday, ..., 7 = Sunday)	Number	1
a	Am/pm marker	Text	PM
H	Hour in day (0-23)	Number	0
k	Hour in day (1-24)	Number	24
K	Hour in am/pm (0-11)	Number	0
h	Hour in am/pm (1-12)	Number	12
m	Minute in hour	Number	30
s	Second in minute	Number	55
S	Millisecond	Number	978
z	Time zone	General time zone	Pacific Standard Time; PST; GMT-08:00
Z	Time zone	RFC 822 time zone	-800
X	Time zone	ISO 8601 time zone	-08; -0800; -08:00

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-M-d H:m:s");
Date today = new Date();
String result = sdf.format(today);
System.out.println(result); //2018-3-11 19:52:11

• parse를 통해 입력 받은 문자열을 날짜로 인식하고 파싱

SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd");
String dateStr = "2018/03/11"
try {
    Date date = sdt.parse(dateStr);
} cateh (ParseExceptrion e) {
    // 문자열 잘못됬을 경우
}

ChoiceFormat

• 특정 범위에 속하는 값을 문자열로 변환
• 2개의 배열을 사용
• 범위의 경계를 저장하는 limit
• 치환활 문자열 저장하는 grades
• pattern 이용하는 방법도 있음
• #은 포함
• <은 포함 X

double[] items = {50, 60, 70, 80, 90};
String[] grades = {"E", "D", "C", "B", "A"};
//String pattern = "50#E|60#D|70<C|80#B|90#A"; 

int[] scores = {88, 100, 90, 83, 60, 56, 33, 45};

ChoiceFormat form = new ChoiceFormat(items, grades);
for (int i =0; i < scores.length; i++) {
    System.out.println(scores[i] + ":"+form.format(scores[i]));
}

MessageFormat

• 2개의 배열을 사용
• {0}, {1}...이런식으로 만들어서 넣으면 됌.