[JAVA] 자바 숫자 단위 10K, 1M, 1B 숫자를 줄여 표기하기

public static String setStringNumber(long count){
 
    if(count >= 1000 && count < 10000){ //1k
        return (count / 1000) + "." + Math.round(count%1000/100) + "K";
    }
    else if(count >= 10000 && count < 100000){ //10k
        return (count / 1000) + "." + Math.round(count%1000/100) + "K";
    }
    else if(count >= 100000 && count < 1000000){ //100k
        return (count / 1000) + "." + Math.round(count%1000/100) + "K";
    }
    else if(count >= 1000000 && count < 10000000){ //1M
        return (count / 1000000) + "." + Math.round(count%1000000/100000) + "M");
    }
    else if(count >= 10000000 && count < 100000000){ //10M
        return (count / 1000000) + "." + Math.round(count%1000000/100000) + "M";
    }
    else if(count >= 100000000 && count < 1000000000){ //100M
        return (count / 1000000) + "." + Math.round(count%1000000/100000) + "M";
    }
    else if(count >= 1000000000){ //1B
        return (count / 1000000000) + "B";
    }
 
    return count+"";
}

long 타입의 숫자 1340을 매개변수로 넣으면

"1.3K" String 문자열로 소수점 첫째자리 까지  반환 해준다.

 

 

Math.round() 함수는 소수점 첫째자리까지 계산

---

- K, M, B 단위 나누는 기준

K : 1,000 = 1K / 10,000 = 10K / 100,000 = 100K

M : 1,000,000 = 1M / 10,000,000 = 10M / 100,000,000 = 100M

B : 1,000,000,000 = 1B / 10,000,000,000 = 10B