java Puzzles 之关于金钱计算那些事 

java Puzzles 之关于金钱计算那些事，java要用int、long、or BigDecimal来计算，一般我们BigDecimal。

package com.doctor.java.puzzle;import java.math.BigDecimal;/** * @author sdcuike * * @time 2016年1月31日 下午9:26:52 *  *       java Puzzles 之关于金钱计算那些事，java要用int、long、or BigDecimal来计算，一般我们BigDecimal。 *  *       警告：用BigDecimal(String)这个构造函数，而非 BigDecimal(double)。 *  *  *       In summary, avoid float and double where exact answers are required; *       for monetary calculations, use int, long, or BigDecimal。 *       not all decimals can be represented exactly using binary floating-point. *  *       There is one caveat: Always use the BigDecimal(String) constructor, *       never BigDecimal(double). The latter constructor creates an instance with the *       exact value of its argument: new BigDecimal(.1) returns a BigDecimal representing 0.1000000000000000055511151231257827021181583404541015625. *  */public class TimeForAChange {    public static void main(String[] args) {        System.out.println(2.00 - 1.10);// 0.8999999999999999        System.out.println(2.00D - 1.10D);// 0.8999999999999999        System.out.println(2.00F - 1.10F);// 0.9        System.out.println(Double.toString(2.00D));// 2.0        System.out.println(BigDecimal.valueOf(2.00).subtract(BigDecimal.valueOf(1.10)));// 0.9        System.out.println(BigDecimal.valueOf(2.00F).subtract(BigDecimal.valueOf(1.10F)));// 0.899999976158142        System.out.println(BigDecimal.valueOf(2.00D).subtract(BigDecimal.valueOf(1.10D)));// 0.9        System.out.println(new BigDecimal("2.00").subtract(new BigDecimal("1.10")));// 0.90    }}