Java 8 | BigInteger longValueExact() 方法和示例

Java.math.BigInteger.longValueExact()是在Java 8 中引入的。它是一个内置函数，可以将 BigInteger 的值转换为 long 并检查丢失的信息。如果 BigInteger 的值大于 9,223,372,036,854,775,807 或小于 -9,223,372,036,854,775,808；该方法将抛出ArithmeticException ，因为 BigInteger 不适合长距离。

句法：

public long longValueExact()

返回值：此方法返回此 BigInteger 的长值。

异常：如果 BigInteger 的值大于 9,223,372,036,854,775,807 或小于 -9,223,372,036,854,775,808，则该方法抛出ArithmeticException ；因为这个范围不适合长距离。

例子：

Input: 98169894145
Output: 98169894145
Explanation: 98169894145 is given as input which is BigInteger
and long value of 98169894145 is 98169894145

Input: -65416518651
Output: -65416518651
Explanation: -65416518651 is given as input which is BigInteger 
and long value of -65416518651 is -65416518651

Input: 10000000000000000000
Output: ArithmeticException
Explanation: When 10000000000000000000 is tried to convert to long,
since 10000000000000000000 > 9,223,372,036,854,775,807 (greater than a long's range), 
therefore it throws an arithmetic exception.

下面的程序说明了 BigInteger 类的 longValueExact() 方法：

程序 1：演示正数 <9,223,372,036,854,775,807 的 longValueExact() 方法

// Java program to demonstrate longValueExact()
// method of BigInteger Class
  
import java.math.*;
  
public class GFG {
  
    public static void main(String[] args)
    {
        // Creating a BigInteger object
        BigInteger big;
        big = new BigInteger("98169894145");
  
        // print value of BigInteger
        System.out.println("BigInteger value : "
                           + big);
  
        // convert big to the long value
        long b1 = big.longValueExact();
  
        // print long value
        System.out.println("long converted value : "
                           + b1);
    }
}

输出：

BigInteger value : 98169894145
long converted value : 98169894145

程序 2：演示负数 >-9,223,372,036,854,775,808 的 longValueExact() 方法

// Java program to demonstrate longValueExact()
// method of BigInteger Class
  
import java.math.*;
  
public class GFG {
  
    public static void main(String[] args)
    {
  
        // Creating a BigInteger object
        BigInteger big = new BigInteger("-65416518651");
  
        // print value of BigInteger
        System.out.println("BigInteger value : "
                           + big);
  
        // convert big to the long value
        long b1 = big.longValueExact();
  
        // print long value
        System.out.println("long converted value : "
                           + b1);
    }
}

输出：

BigInteger value : -65416518651
long converted value : -65416518651

程序 3：演示负数 <-9,223,372,036,854,775,808 的 longValueExact() 方法。它会抛出算术异常

// Java program to demonstrate longValueExact()
// method of BigInteger Class
  
import java.math.*;
  
public class GFG {
  
    public static void main(String[] args)
    {
  
        // Creating a BigInteger object
        BigInteger big = new BigInteger("-10000000000000000000");
  
        // print value of BigInteger
        System.out.println("BigInteger value : "
                           + big);
  
        try {
            // convert big to the long value
            long b1 = big.longValueExact();
  
            // print long value
            System.out.println("long converted value : "
                               + b1);
        }
        catch (Exception e) {
            System.out.println("Exception: " + e);
        }
    }
}

输出：

BigInteger value : -10000000000000000000
Exception: java.lang.ArithmeticException: BigInteger out of long range

程序 4：演示正数 >9,223,372,036,854,775,807 的 longValueExact() 方法。它会抛出算术异常

// Java program to demonstrate longValueExact()
// method of BigInteger Class
  
import java.math.*;
  
public class GFG {
  
    public static void main(String[] args)
    {
  
        // Creating a BigInteger object
        BigInteger big = new BigInteger("10000000000000000000");
  
        // print value of BigInteger
        System.out.println("BigInteger value : "
                           + big);
  
        try {
            // convert big to the long value
            long b1 = big.longValueExact();
  
            // print long value
            System.out.println("long converted value : "
                               + b1);
        }
        catch (Exception e) {
            System.out.println("Exception: " + e);
        }
    }
}

输出：

BigInteger value : 10000000000000000000
Exception: java.lang.ArithmeticException: BigInteger out of long range

参考： https: Java