bigentermath floweroftwo()函数|番石榴| Java

原文:https://www . geesforgeks . org/bigintermath-floweroftwo-function-guava-Java/

番石榴的大整数类的方法flower powerof two(大整数 x) 返回小于或等于 x 的 2 的最大幂，这相当于大整数. valueOf(2)。pow(log2(x，FLOOR))。 语法:

public static BigInteger floorPowerOfTwo(BigInteger x)

参数:该方法以大整数 x 为参数，求其二的底幂。 返回值:此方法返回小于等于 x 的 2 的最大幂。 异常:此方法抛出IllegalArgumentException如果 x < = 0 。 以下示例说明了 BigIntegerMath.floorPowerOfTwo()方法: 示例 1:

Java 语言(一种计算机语言，尤用于创建网站)

// Java code to show implementation of
// floorPowerOfTwo() 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(10);

        // Using floorPowerOfTwo(BigInteger x) method
        // of Guava's BigIntegerMath class
        BigInteger
            ans1
            = BigIntegerMath.floorPowerOfTwo(n1);

        System.out.println("Largest power of 2 less "
                           + "than or equal to " + n1
                           + " is: " + ans1);

        BigInteger n2 = BigInteger.valueOf(127);

        // Using floorPowerOfTwo(BigInteger x) method
        // of Guava's BigIntegerMath class
        BigInteger
            ans2
            = BigIntegerMath.floorPowerOfTwo(n2);

        System.out.println("Largest power of 2 less "
                           + "than or equal to " + n2
                           + " is: " + ans2);
    }
}

输出:

Largest power of 2 less than or equal to 10 is: 8
Largest power of 2 less than or equal to 127 is: 64

示例 2: 显示非法文档异常

Java 语言(一种计算机语言，尤用于创建网站)

// Java code to show implementation of
// floorPowerOfTwo(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 n1 = BigInteger.valueOf(-3);

            // Using floorPowerOfTwo(BigInteger x) method
            // of Guava's BigIntegerMath class
            // This should raise "IllegalArgumentException"
            // as x <= 0
            BigInteger
                ans1
                = BigIntegerMath.floorPowerOfTwo(n1);

            System.out.println("Largest power of 2 less "
                               + "than or equal to " + n1
                               + " is: " + ans1);
        }
        catch (Exception e) {
            System.out.println("Exception: " + e);
        }
    }
}

输出:

Exception: java.lang.IllegalArgumentException: x (-3) must be > 0

参考:https://Google . github . io/guava/releases/21.0/API/docs/com/Google/common/math/bigintermath . html # floweroftwo-Java . math . biginger-

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