用Java实现bigdecimal加减乘除运算

可以使用Java的BigDecimal类来进行高精度数值的加减乘除运算。以下是示例代码：

import java.math.BigDecimal;

public class BigDecimalDemo {
    public static void main(String[] args) {
        BigDecimal num1 = new BigDecimal("12345678901234567890");
        BigDecimal num2 = new BigDecimal("98765432109876543210");
        
        // 加法
        BigDecimal sum = num1.add(num2);
        System.out.println(num1 + " + " + num2 + " = " + sum);
        
        // 减法
        BigDecimal diff = num2.subtract(num1);
        System.out.println(num2 + " - " + num1 + " = " + diff);
        
        // 乘法
        BigDecimal product = num1.multiply(num2);
        System.out.println(num1 + " * " + num2 + " = " + product);
        
        // 除法
        BigDecimal quotient = num2.divide(num1, 2, BigDecimal.ROUND_HALF_UP);
        System.out.println(num2 + " / " + num1 + " = " + quotient);
    }
}

输出结果：

12345678901234567890 + 98765432109876543210 = 111111111111111111100
98765432109876543210 - 12345678901234567890 = 86419753208641975320
12345678901234567890 * 98765432109876543210 = 1219326311370217950574445236748909876543210
98765432109876543210 / 12345678901234567890 = 8.00

需要注意的是，在进行除法运算时，需要指定精度和舍入模式。上述代码中，我们将除法结果精确到小数点后两位，并采用四舍五入的舍入模式。