Java - rounding by quarter intervals

问题

I'm running into following issue...

Does an already 'built-in' function exists in java to round given random numbers to the closest lower quarter value.

These are the given random numbers:

2.00 -> 2.00
2.24 -> 2.00
2.25 -> 2.25
2.49 -> 2.25
2.50 -> 2.50
2.74 -> 2.50
2.75 -> 2.75
2.99 -> 2.75
3.00 -> 3.00

回答1:

You can multiply the value by 4 then floor it then divide by 4.

public static double quarterRound(double v){
   return Math.floor(v*4)/4;
}

回答2:

You need to round to quarters so:

• Multiply by 4
• Floor to next int
• Divide by 4

Note that if you reliable values it is better to works with BigDecimal instead of primitive values (double or float). The algorithm stay the same.

回答3:

Try this:

double value = 2.99D;
value = (double)(int)(value * 4) / 4;

来源：https://stackoverflow.com/questions/32274898/java-rounding-by-quarter-intervals