Java 番石榴| long math 类的 pow(long b，int k)带示例
原文:https://www . geesforgeks . org/Java-guava-pow long-b-int-k-of-long math-class-with-examples/
番石榴龙数学类的方法幂(长 b，int k) 将 b 返回到第 kth 幂。即使结果溢出，也等于 BigInteger.valueOf(b)。功率(k)。longValue()。该实现在 O(log k) 时间运行。
语法:
public static long pow(long b, int k)
参数:该方法接受两个参数，b 和 k，参数 b 称为基，加到 k 次幂。
返回值:此方法返回 b 的 k 次幂。
异常:如果 k 为负，此方法抛出IllegalArgumentException。
例 1:
// Java code to show implementation of
// pow(long b, int k) 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 b1 = 4;
int k1 = 5;
long ans1 = LongMath.pow(b1, k1);
System.out.println(b1 + " to the " + k1
+ "th power is: "
+ ans1);
long b2 = 12;
int k2 = 3;
long ans2 = LongMath.pow(b2, k2);
System.out.println(b2 + " to the " + k2
+ "rd power is: "
+ ans2);
}
}
输出:
4 to the 5th power is: 1024
12 to the 3rd power is: 1728
例 2:
// Java code to show implementation of
// pow(long b, int k) method of Guava's
// LongMath class
import java.math.RoundingMode;
import com.google.common.math.LongMath;
class GFG {
static long findPow(long b, int k)
{
try {
// Using pow(long b, int k)
// method of Guava's LongMath class
// This should throw "IllegalArgumentException"
// as k < 0
long ans = LongMath.pow(b, k);
// Return the answer
return ans;
}
catch (Exception e) {
System.out.println(e);
return -1;
}
}
// Driver code
public static void main(String args[])
{
long b = 4;
int k = -5;
try {
// Using pow(long b, int k)
// method of Guava's LongMath class
// This should throw "IllegalArgumentException"
// as k < 0
LongMath.pow(b, k);
}
catch (Exception e) {
System.out.println(e);
}
}
}
输出:
java.lang.IllegalArgumentException: exponent (-5) must be >= 0
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