Java番石榴 |带示例的 LongMath 类的 sqrt(long x, RoundingMode 模式)

Guava 的 LongMath 类的方法sqrt(long x, RoundingMode mode)接受两个参数，根据第二个参数指定的舍入模式计算第一个参数的平方根。

句法：

public static long sqrt(long x, RoundingMode mode)

参数：此方法有两个参数：

• x:是要求平方根的长整型值。
• mode：是舍入模式，根据该模式进行舍入。

返回值：该方法返回x 的平方根，根据指定的舍入方式进行舍入。

例外：此方法抛出以下参数：

• IllegalArgumentException：如果 x < 0。
• ArithmeticException：如果模式是 RoundingMode.UNNECESSARY 并且 sqrt(x) 不是整数。

枚举舍入模式

Enum Constant	Description
CEILING	Rounding mode to round towards positive infinity.
DOWN	Rounding mode to round towards zero.
FLOOR	Rounding mode to round towards negative infinity.
HALF_DOWN	Rounding mode to round towards “nearest neighbor” unless both neighbors are equidistant, in which case round down.
HALF_EVEN	Rounding mode to round towards the “nearest neighbor” unless both neighbors are equidistant, in which case, round towards the even neighbor.
HALF_UP	Rounding mode to round towards “nearest neighbor” unless both neighbors are equidistant, in which case round up.
UNNECESSARY	Rounding mode to assert that the requested operation has an exact result, hence no rounding is necessary.
UP	Rounding mode to round away from zero.

下面给出了一些示例，以更好地理解实现：

示例 1：

// Java code to show implementation of
// sqrt(long x, RoundingMode mode) method
// of Guava's LongMath class
  
import java.math.RoundingMode;
import com.google.common.math.LongMath;
  
class GFG {
  
    // Driver code
    public static void main(String args[])
    {
        long x1 = 524;
  
        // Using sqrt(long x, RoundingMode mode)
        // method of Guava's LongMath class
        // The RoundingMode HALF_EVEN rounds towards
        // the nearest neighbor unless both neighbors
        // are equidistant, in which case, round towards
        // the even neighbor.
        long ans1
            = LongMath.sqrt(x1,
                            RoundingMode.HALF_EVEN);
  
        System.out.println("Square root of " + x1
                           + " is : " + ans1);
  
        long x2 = 316;
  
        // Using sqrt(long x, RoundingMode mode)
        // method of Guava's LongMath class
        // The RoundingMode FLOOR rounds towards
        // negative infinity.
        long ans2
            = LongMath.sqrt(x2,
                            RoundingMode.FLOOR);
  
        System.out.println("Square root of " + x2
                           + " is : " + ans2);
    }
}

输出：

Square root of 524 is : 23
Square root of 316 is : 17

示例 2：

// Java code to show implementation of
// sqrt(long x, RoundingMode mode) method
// of Guava's LongMath class
  
import java.math.RoundingMode;
import com.google.common.math.LongMath;
  
class GFG {
  
    // Driver code
    public static void main(String args[])
    {
        int x = -65;
  
        try {
            // Using sqrt(long x, RoundingMode mode)
            // method of Guava's LongMath class
            // The RoundingMode HALF_EVEN rounds towards
            // the nearest neighbor unless both neighbors
            // are equidistant, in which case, round towards
            // the even neighbor.
  
            // This should throw "IllegalArgumentException"
            // as x < 0
            long ans1 = LongMath.sqrt(x,
                                      RoundingMode.HALF_EVEN);
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

输出：

java.lang.IllegalArgumentException: x (-65) must be >= 0

参考： https://google.github.io/guava/releases/20.0/api/docs/com/google/common/math/LongMath.html#sqrt-long-java.math.RoundingMode-