BigDecimal.add()方法

超、凢脫俗 2023-09-28 11:59 10阅读 0赞

BigDecimal.add()方法误区：

BigDecimal totalAmount = new BigDecimal("666");
    totalAmount.add(new BigDecimal("888"));
    System.out.println(totalAmount);

此时输出并不是加之后的值，而是加之前的值，是因为源码中有介绍@return \{@code this + augend\}  
返回值才是需要的结果，而不是在原数据上进行操作。

// Arithmetic Operations
        /**
         * Returns a {@code BigDecimal} whose value is {@code (this +
         * augend)}, and whose scale is {@code max(this.scale(),
         * augend.scale())}.
         *
         * @param  augend value to be added to this {@code BigDecimal}.
         * @return {@code this + augend}
         */
        public BigDecimal add(BigDecimal augend) {
        
            if (this.intCompact != INFLATED) {
        
                if ((augend.intCompact != INFLATED)) {
        
                    return add(this.intCompact, this.scale, augend.intCompact, augend.scale);
                } else {
        
                    return add(this.intCompact, this.scale, augend.intVal, augend.scale);
                }
            } else {
        
                if ((augend.intCompact != INFLATED)) {
        
                    return add(augend.intCompact, augend.scale, this.intVal, this.scale);
                } else {
        
                    return add(this.intVal, this.scale, augend.intVal, augend.scale);
                }
            }
        }

正确结果应是其返回值：

BigDecimal totalAmount = new BigDecimal("666");
    totalAmount.add(new BigDecimal("888"));
    System.out.println(totalAmount);
    BigDecimal result = totalAmount.add(new BigDecimal("888"));
    System.out.println(result);

输出：  
![在这里插入图片描述][360880c17aec4097857fb6f6bdfec567.png]

[360880c17aec4097857fb6f6bdfec567.png]: https://img-blog.csdnimg.cn/360880c17aec4097857fb6f6bdfec567.png