BigDecimal类round()方法 (BigDecimal Class round() method)

• round() method is available in java.math package.

  round()方法在java.math包中可用。

• round() method is used to get a rounded BigDecimal based on the given MathContext setting when the precision value is not equal to 0 otherwise there is no effect of rounding when the precision value is equal to 0.

  当精度值不等于0时，使用round()方法基于给定的MathContext设置获取舍入的BigDecimal，否则，当精度值等于0时就没有舍入效果。

• round() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.

  round()方法是一个非静态方法，只能通过类对象访问，如果尝试使用类名称访问该方法，则会收到错误消息。

• round() method may throw an exception at the time of rounding.

  round()方法在四舍五入时可能会引发异常。

  ArithmeticException: This exception may throw when this BigDecimal need rounding and the mode of rounding is set to "UNNECESSARY".

  ArithmeticException ：当此BigDecimal需要舍入并且舍入模式设置为“ UNNECESSARY”时，可能引发此异常。

Syntax:

句法：

public BigDecimal round(MathContext ma_co);

Parameter(s):

参数：

• MathContext ma_co – represents the MathContext to use in rounding BigDecimal.

  MathContext ma_co –表示四舍五入BigDecimal时使用的MathContext。

Return value:

返回值：

The return type of this method is BigDecimal, it returns the rounded BigDecimal based on the given MathContext.

此方法的返回类型为BigDecimal ，它根据给定的MathContext返回四舍五入的BigDecimal。

Example:

例：

// Java program to demonstrate the example // of BigDecimal round(MathContext ma_co) method of BigDecimalimport java.math.*;public class RoundOfBD {
       public static void main(String args[]) {
           // Initialize two variables and        // first is of "short" and second is          // of "String" type        short val1 = 1321;        String val2 = "100.24";        // Initialize two BigDecimal objects and        // one MathContext        BigDecimal b_dec1 = new BigDecimal(val1);        BigDecimal b_dec2 = new BigDecimal(val2);        MathContext ma_co = new MathContext(4, RoundingMode.CEILING);        // round this BigDecimal b_dec1 according to        // the given MathContext based on precision        // and rounding mode        BigDecimal round = b_dec1.round(ma_co);        System.out.println("b_dec1.round(ma_co): " + round);        // round this BigDecimal b_dec1 according to        // the given MathContext based on precision        // and rounding mode        round = b_dec2.round(ma_co);        System.out.println("b_dec2.round(ma_co): " + round);    }}

Output

输出量

b_dec1.round(ma_co): 1321b_dec2.round(ma_co): 100.3

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