Java Guava BigIntegerMath ceilingPowerOfTwo()用法及代码示例

Guava BigIntegerMath类的ceilingPowerOfTwo(BigInteger x)方法返回大于或等于x的2的最小幂。这等效于BigInteger.valueOf(2).pow(log2(x，CEILING))。

用法:

public static BigInteger 
    ceilingPowerOfTwo(BigInteger x)

参数：此方法将数字x作为其最大幂为2的参数。

返回值：此方法返回给定数字x的2的上限功率。

异常：如果x <= 0，则此方法引发IllegalArgumentException。

以下示例说明了BifIntegerMath.ceilingPowerOfTwo()方法：

范例1：

// Java code to show implementation of 
// ceilingPowerOfTwo(BigInteger x) method 
// of Guava's BigIntegerMath class 
  
import java.math.*; 
import com.google.common.math.BigIntegerMath; 
  
class GFG { 
  
    // Driver code 
    public static void main(String args[]) 
    { 
        BigInteger n1 = BigInteger.valueOf(25); 
  
        // Using ceilingPowerOfTwo(BigInteger x) method of 
        // Guava's BigIntegerMath class 
        BigInteger ans = BigIntegerMath.ceilingPowerOfTwo(n1); 
  
        System.out.println("Smallest power of 2 greater "
                           + "than or equal to "
                           + n1 + " is:" + ans); 
  
        BigInteger n2 = BigInteger.valueOf(65); 
  
        // Using ceilingPowerOfTwo(BigInteger x) method of 
        // Guava's BigIntegerMath class 
        BigInteger ans1 = BigIntegerMath.ceilingPowerOfTwo(n2); 
  
        System.out.println("Smallest power of 2 greater "
                           + "than or equal to "
                           + n2 + " is:" + ans1); 
    } 
}

输出：

Smallest power of 2 greater than or equal to 25 is:32
Smallest power of 2 greater than or equal to 65 is:128

范例2：

// Java code to show implementation of 
// ceilingPowerOfTwo(BigInteger x) method 
// of Guava's BigIntegerMath class 
  
import java.math.*; 
import com.google.common.math.BigIntegerMath; 
  
class GFG { 
  
    // Driver code 
    public static void main(String args[]) 
    { 
  
        try { 
  
            BigInteger n = BigInteger.valueOf(0); 
  
            // Using ceilingPowerOfTwo(BigInteger x) method of 
            // Guava's BigIntegerMath class 
            // This should raise "IllegalArgumentException" 
            // as n is <= 0 
            BigInteger ans = BigIntegerMath.ceilingPowerOfTwo(n); 
  
            System.out.println("Smallest power of 2 greater "
                               + "than or equal to n is:" + ans); 
        } 
        catch (Exception e) { 
            System.out.println("Exception:" + e); 
        } 
    } 
}

输出：

Exception:java.lang.IllegalArgumentException:x (0) must be > 0

参考： https://google.github.io/guava/releases/21.0/api/docs/com/google/common/math/BigIntegerMath.html#ceilingPowerOfTwo-java.math.BigInteger-

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注：本文由纯净天空筛选整理自Sahil_Bansall大神的英文原创作品 BigIntegerMath ceilingPowerOfTwo() function | Guava | Java。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。