货币计算为什么使用BigDecimal

double d = 29.0 * 0.01;
System.out.println(d);
System.out.println(d * 100);
System.out.println((int) (d * 100));

  输出：

0.29
28.999999999999996
28

float f = (float) (29.45*0.01);
System.out.println(f);
System.out.println(f * 100);
System.out.println((int) (f * 100));

  输出：

0.2945
29.449999
29

//需要使用String初始化对象
BigDecimal x = new BigDecimal("500000000.00");
BigDecimal y = new BigDecimal("0.6");
BigDecimal z = x.multiply(y);
System.out.println(">>>>>>>>>> "+z);
>>>>>>>>>> 300000000.000

BigDecimal x2 = new BigDecimal(500000001);
BigDecimal y2 = new BigDecimal(0.6);
BigDecimal z2 = x2.multiply(y2);
>>>>>>>>>> 300000000.59999998889776973154397410326055251061916351318359375
System.out.println(">>>>>>>>>> "+z2);

BigDecimal equals 
     * this method considers two BigDecimal objects 
     * equal only if they are equal in value and scale
     * thus 2.0 is not equal to 2.00 when compared by this method.

评论

1 楼 h416373073 2017-03-02