I want a function to convert Bigdecimal 10.12 for 10.12345 and 10.13 for 10.12556.
But no function is satisfying both conversion in same time.Please help to achieve this.
Below is what I tried.
With value 10.12345:
BigDecimal a = new BigDecimal("10.12345");
a.setScale(2, BigDecimal.ROUND_UP)
a.setScale(2, BigDecimal.ROUND_CEILING)
a.setScale(2, BigDecimal.ROUND_DOWN)
a.setScale(2, BigDecimal.ROUND_FLOOR)
a.setScale(2, BigDecimal.ROUND_HALF_DOWN)
a.setScale(2, BigDecimal.ROUND_HALF_EVEN)
a.setScale(2, BigDecimal.ROUND_HALF_UP)
Output :
10.12345::10.13
10.12345::10.13
10.12345::10.12
10.12345::10.12
10.12345::10.12
10.12345::10.12
10.12345::10.12
With value 10.12556:
BigDecimal b = new BigDecimal("10.12556");
b.setScale(2, BigDecimal.ROUND_UP)
b.setScale(2, BigDecimal.ROUND_CEILING)
b.setScale(2, BigDecimal.ROUND_DOWN)
b.setScale(2, BigDecimal.ROUND_FLOOR)
b.setScale(2, BigDecimal.ROUND_HALF_DOWN)
b.setScale(2, BigDecimal.ROUND_HALF_EVEN)
b.setScale(2, BigDecimal.ROUND_HALF_UP)
Output :
10.12556::10.13
10.12556::10.13
10.12556::10.12
10.12556::10.12
10.12556::10.12
10.12556::10.12
10.12556::10.12
This question is related to
java
bigdecimal
I think that the RoundingMode you are looking for is ROUND_HALF_EVEN. From the javadoc:
Rounding mode to round towards the "nearest neighbor" unless both neighbors are equidistant, in which case, round towards the even neighbor. Behaves as for ROUND_HALF_UP if the digit to the left of the discarded fraction is odd; behaves as for ROUND_HALF_DOWN if it's even. Note that this is the rounding mode that minimizes cumulative error when applied repeatedly over a sequence of calculations.
Here is a quick test case:
BigDecimal a = new BigDecimal("10.12345");
BigDecimal b = new BigDecimal("10.12556");
a = a.setScale(2, BigDecimal.ROUND_HALF_EVEN);
b = b.setScale(2, BigDecimal.ROUND_HALF_EVEN);
System.out.println(a);
System.out.println(b);
Correctly prints:
10.12
10.13
UPDATE:
setScale(int, int) has not been recommended since Java 1.5, when enums were first introduced, and was finally deprecated in Java 9. You should now use setScale(int, RoundingMode) e.g:
setScale(2, RoundingMode.HALF_EVEN)
Add 0.001 first to the number and then call setScale(2, RoundingMode.ROUND_HALF_UP)
Code example:
public static void main(String[] args) {
BigDecimal a = new BigDecimal("10.12445").add(new BigDecimal("0.001"));
BigDecimal b = a.setScale(2, BigDecimal.ROUND_HALF_UP);
System.out.println(b);
}
You can call setScale(newScale, roundingMode) method three times with changing the newScale value from 4 to 3 to 2 like
First case
BigDecimal a = new BigDecimal("10.12345");
a = a.setScale(4, BigDecimal.ROUND_HALF_UP);
System.out.println("" + a); //10.1235
a = a.setScale(3, BigDecimal.ROUND_HALF_UP);
System.out.println("" + a); //10.124
a = a.setScale(2, BigDecimal.ROUND_HALF_UP);
System.out.println("" + a); //10.12
Second case
BigDecimal a = new BigDecimal("10.12556");
a = a.setScale(4, BigDecimal.ROUND_HALF_UP);
System.out.println("" + a); //10.1256
a = a.setScale(3, BigDecimal.ROUND_HALF_UP);
System.out.println("" + a); //10.126
a = a.setScale(2, BigDecimal.ROUND_HALF_UP);
System.out.println("" + a); //10.13
You may try this:
public static void main(String[] args) {
BigDecimal a = new BigDecimal("10.12345");
System.out.println(toPrecision(a, 2));
}
private static BigDecimal toPrecision(BigDecimal dec, int precision) {
String plain = dec.movePointRight(precision).toPlainString();
return new BigDecimal(plain.substring(0, plain.indexOf("."))).movePointLeft(precision);
}
OUTPUT:
10.12
Source: Stackoverflow.com