BigDecimal 学习比较

    /**
     * 解决精度的问题
     */
    @Test
    void testBigDecimal() {

        /**
         * no problem
         */
        System.out.println(new BigDecimal("1225.12").setScale(2));
        System.out.println(new BigDecimal("1225.1").setScale(2));
        System.out.println(new BigDecimal("1225").setScale(2));

        /**
         * has problem
         */
        System.out.println(new BigDecimal("1225.120").setScale(2)); // ok

        /**
         * error : java.lang.ArithmeticException: Rounding necessary
         * solution : 设置舍入模式, 使用 setScale(int newScale, RoundingMode roundingMode); 方法
         */
        System.out.println(new BigDecimal("1225.121").setScale(2)); // error
        System.out.println(new BigDecimal("1225.121").setScale(2, BigDecimal.ROUND_HALF_UP)); // right
        System.out.println(new BigDecimal("1225.121").setScale(2, RoundingMode.HALF_UP)); // right

    }