자바 Math.ceil 사용 방법

자바 Math.ceil 을 그냥 막 쓰면 정수가 나온다. 때문에 아래와 같이 double로 형변환을 해야 소수점이 발생하여 정상적으로 ceil 을 할 수 있다.

System.out.println((double) 12000 / 5000);
int n = (int) Math.ceil((double) 12000 / 5000);
System.out.println(n);
             		

결과

2.4
3

즉, 12000을 5000 으로 나누면 2.4가 나오고 ceil 을 하면 3이 된다.

 

자바 api 설명

double java.lang.Math.ceil(double a)

• ceilpublic static double ceil(double a)

  Returns the smallest (closest to negative infinity) double value that is greater than or equal to the argument and is equal to a mathematical integer. Special cases:

  • If the argument value is already equal to a mathematical integer, then the result is the same as the argument.
  • If the argument is NaN or an infinity or positive zero or negative zero, then the result is the same as the argument.
  • If the argument value is less than zero but greater than -1.0, then the result is negative zero.

  Note that the value of Math.ceil(x) is exactly the value of -Math.floor(-x).

  Parameters:a - a value.Returns:the smallest (closest to negative infinity) floating-point value that is greater than or equal to the argument and is equal to a mathematical integer.