Java番石榴 |带有示例的 LongMath.checkedMultiply(int a, int b) 方法

checkedMultiply(long a, long b)是 Guava 的 LongMath 类的一个方法，它接受两个参数a和b ，并返回它们的乘积。

句法：

public static long checkedMultiply(long a, long b)

参数：该方法接受两个 long 值a和b并计算它们的乘积。

返回值：该方法返回传递给它的长值的乘积，前提是它不会溢出。

例外：如果乘积，即 (a – b) 在有符号长算术中溢出，则方法 checkedMultiply(long a, long b) 将引发ArithmeticException 。

下面的例子说明了上述方法的实现：

示例 1：

// Java code to show implementation of
// checkedMultiply(long a, long b) 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 a1 = 25;
        long b1 = 36;
  
        // Using checkedMultiply(long a, long b)
        // method of Guava's LongMath class
        long ans1 = LongMath.checkedMultiply(a1, b1);
  
        System.out.println("Product of " + a1 + " and "
                           + b1 + " is: " + ans1);
  
        long a2 = 150;
        long b2 = 667;
  
        // Using checkedMultiply(long a, long b)
        // method of Guava's LongMath class
        long ans2 = LongMath.checkedMultiply(a2, b2);
  
        System.out.println("Product of " + a2 + " and "
                           + b2 + " is: " + ans2);
    }
}

输出：

Product of 25 and 36 is: 900
Product of 150 and 667 is: 100050

示例 2：

// Java code to show implementation of
// checkedMultiply(long a, long b) method
// of Guava's LongMath class
  
import java.math.RoundingMode;
import com.google.common.math.LongMath;
  
class GFG {
  
    static long findDiff(long a, long b)
    {
        try {
  
            // Using checkedMultiply(long a, long b) method
            // of Guava's LongMath class
            // This should throw "ArithmeticException"
            // as the product overflows in signed
            // long arithmetic
            long ans = LongMath.checkedMultiply(a, b);
  
            // Return the answer
            return ans;
        }
        catch (Exception e) {
            System.out.println(e);
            return -1;
        }
    }
  
    // Driver code
    public static void main(String args[])
    {
        long a = Long.MIN_VALUE;
        long b = 452;
  
        try {
  
            // Function calling
            findDiff(a, b);
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

输出：

java.lang.ArithmeticException: overflow

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