BigDecimal的setScale四大常用方法总结

// 设置小数点后第三位数字一大一小观察效果
BigDecimal num =  new BigDecimal("3.3235667");
BigDecimal numOne =  new BigDecimal("3.3275667");
1、ROUND_UP:进位制:不管保留数字后面是大是小(0除外)都会进1

// ROUND_UP--进位制:不管保留数字后面是大是小(0除外)都会进1
BigDecimal num1 = num.setScale(2,BigDecimal.ROUND_UP);
System.out.println("SmallROUND_UP:"+num1);
BigDecimal numTwo = numOne.setScale(2,BigDecimal.ROUND_UP);
System.out.println("BigROUND_UP:"+numTwo);
打印结果:SmallROUND_UP:3.33  
     BigROUND_UP:3.33
2、ROUND_DOWN:保留设置数字,后面所有直接去除

 // ROUND_DOWN--保留设置数字,后面所有直接去除

BigDecimal num2 = num.setScale(2,BigDecimal.ROUND_DOWN);
System.out.println("SmallROUND_DOWN:"+num2);
BigDecimal numThree = numOne.setScale(2,BigDecimal.ROUND_DOWN);
System.out.println("BigROUND_DOWN:"+numThree);

打印结果:SmallROUND_DOWN:3.32
      BigROUND_DOWN:3.32
3、ROUND_HALF_UP:根据保留数字后一位>=5进行四舍五入

// ROUND_HALF_UP--根据保留数字后一位>=5进行四舍五入
BigDecimal num3 = num.setScale(2,BigDecimal.ROUND_HALF_UP);
System.out.println("SmallROUND_HALF_UP:"+num3);
BigDecimal numFour = numOne.setScale(2,BigDecimal.ROUND_HALF_UP);
System.out.println("BigROUND_HALF_UP:"+numFour);
打印结果:SmallROUND_HALF_UP:3.32
      BigROUND_HALF_UP:3.33
4、ROUND_HALF_DOWN:根据保留数字后一位>5进行四舍五入

BigDecimal num4 = num.setScale(2,BigDecimal.ROUND_HALF_DOWN);
System.out.println("SmallROUND_HALF_DOWN:"+num4);
BigDecimal numFive = numOne.setScale(2,BigDecimal.ROUND_HALF_DOWN);
System.out.println("BigROUND_HALF_DOWN:"+numFive);
打印结果:SmallROUND_HALF_DOWN:3.32
      BigROUND_HALF_DOWN:3.33

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