Java 四舍五入

我怎样才能将 numberGrade 的值向上舍入，这样如果它是 89.5，它就会变为 90。 numberGrade 被视为双精度值，但将其设为 int 不会将其向上或向下舍入。

public class GradeReporter
{
    // The limit is the inclusive lower limit for each letter
    // grade -- this means that 89.5 is an 'A' not a 'B'
    public static final double A_LIMIT = 90;
    public static final double B_LIMIT = 80;
    public static final double C_LIMIT = 70;
    public static final double D_LIMIT = 60;
    public static final double F_LIMIT = 60;

    /** Converts a numeric grade into a letter grade. Grades should be rounded to 
     *  nearest whole number
     *
     * @param a numeric grade in the range of 0 to 100
     * @returns a letter grade based on the numeric grade, possible grades are A, B, C, D and F.
     */
    public char letterGrade(double numberGrade)
    {
        int grade = int(numberGrade);
        if (grade >= A_LIMIT)
            letterGrade = 'A';
        else if (grade >= B_LIMIT)
            letterGrade = 'B';
        else if (grade >= C_LIMIT)
            letterGrade = 'C';
        else if (grade >= D_LIMIT)
            letterGrade = 'D';
        else if (grade < F_LIMIT)//4
            letterGrade = 'F';
        return letterGrade;
    }

去圆up， 您可以使用Math.ceil(numberGrade)。要舍入到最接近的整数，请使用Math.round(numberGrade).

See: the Math class http://download.oracle.com/javase/6/docs/api/java/lang/Math.html