Java番石榴 | IntMath 类的 sqrt(int x, RoundingMode mode) 方法

Guava 的 IntMath 类的方法sqrt(int x, RoundingMode mode)返回 x 的平方根，用指定的舍入模式四舍五入。

句法：

public static int sqrt(int x, RoundingMode mode)

例外：

• 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(int x, RoundingMode mode) method
// of Guava's IntMath class
  
import java.math.RoundingMode;
import com.google.common.math.IntMath;
  
class GFG {
  
    // Driver code
    public static void main(String args[])
    {
        int x1 = 226;
  
        // Using sqrt(int x, RoundingMode mode)
        // method of Guava's IntMath class
        // The RoundingMode HALF_EVEN rounds towards
        // the nearest neighbor unless both neighbors
        // are equidistant, in which case, round towards
        // the even neighbor.
        int ans1 = IntMath.sqrt(x1,
                                RoundingMode.HALF_EVEN);
  
        System.out.println("Square root of x1 is: "
                           + ans1);
  
        int x2 = 154;
  
        // Using sqrt(int x, RoundingMode mode)
        // method of Guava's IntMath class
        // The RoundingMode FLOOR rounds towards
        // negative infinity.
        int ans2 = IntMath.sqrt(x2,
                                RoundingMode.FLOOR);
  
        System.out.println("Square root of x2 is: "
                           + ans2);
    }
}

输出：

Square root of x1 is: 15
Square root of x2 is: 12

示例 2：

// Java code to show implementation of
// sqrt(int x, RoundingMode mode) method
// of Guava's IntMath class
  
import java.math.RoundingMode;
import com.google.common.math.IntMath;
  
class GFG {
  
    // Driver code
    public static void main(String args[])
    {
        int x1 = -65;
        try {
            // Using sqrt(int x, RoundingMode mode)
            // method of Guava's IntMath 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 x1 < 0
            int ans1 = IntMath.sqrt(x1,
                                    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/IntMath.html#sqrt-int-java.math.RoundingMode-