This question already has answers here:
Int division: Why is the result of 1/3 == 0?
(19 answers)
Closed 4 years ago.
I want to calculate the of a number I receive in BigDecimal format :
BigDecimal number1 = new BigDecimal("17");
int percentage = 50;
BigDecimal percentageAmount = number1.multiply(new BigDecimal(percentage/100));
but I got a 0 !
Cast the divided result to double. The integer division is returning zero as expected. This should work.
BigDecimal percentageAmount = number1.multiply(new BigDecimal((double)percentage/100));
Or, make the 100 to 100.0.
BigDecimal percentageAmount = number1.multiply(new BigDecimal(percentage/100.0));
These solutions would work if the number is small as you have used. But these solutions won't give the precise results when the number is big. This would be the best approach for avoiding the precision error:
BigDecimal percentageAmount = number1.multiply(BigDecimal.valueOf((double)percentage/100));
Related
This question already has answers here:
Is floating point math broken?
(31 answers)
Closed 1 year ago.
When I divided the large number into a small number then the division is correct but when I write the small number to divide a large number the answer returns wrong. In my scenario, the small number always be first. here is my code this code return 7.4074074074074075E-6 but the correct result is 0.0000074074.
double itf = 0.0;
double a = 4.0;
double b = 540000;
itf = a / b;
Log.i(TAG, "savedata: outputvalue=" + itf);
BigDecimal a = new BigDecimal("4");
BigDecimal b = new BigDecimal("540000");
// 0.0000074074
a.divide(b, MathContext.DECIMAL128);
You should use a decimal type. double is outside the scope of support
This question already has answers here:
Int division: Why is the result of 1/3 == 0?
(19 answers)
Closed 2 years ago.
I am trying to show the percentage of day passed using a fixed time. However, when I divide the time passed already by the total amount of time (in seconds) of a day, I get 0.0. I put the current values into the console. Any help is appreciated.
You are performing integer division, and then casting it to a double. You should be doing:
int numOfSecondsSinceMidnight = 61960;
int totalDay = 86400;
double percentDayPassed = 0;
percentDayPassed = (((double)numOfSecondsSinceMidnight / totalDay)*100);
System.out.println(percentDayPassed);
Or better yet, changing numOfSecondsSinceMidnight and totalDay to doubles:
double numOfSecondsSinceMidnight = 61960;
double totalDay = 86400;
double percentDayPassed = 0;
percentDayPassed = ((numOfSecondsSinceMidnight / totalDay)*100);
System.out.println(percentDayPassed);
Both of which print:
71.71296296296296
This question already has answers here:
Integer division: How do you produce a double?
(11 answers)
Closed 2 years ago.
I'm trying to get a number when I divide 2 numbers together:
int wins = 3070;
int n = 10000;
double probability = wins/n;
System.out.println(probability);
All it prints is: 0.0
But I'm expecting it to print: 0.307
Atleast one of the values (numerator or denominator) should be type casted with double. Integer divided by integer would result integer. If one of them would be double then result would be upcasted to double. Try it! It should work!
This question already has answers here:
How can I divide properly using BigDecimal
(2 answers)
Closed 5 years ago.
The title says it all: How do I divide a BigInteger by a floating point number in Java? I don’t need the fraction part of the division, it is okay to have it either rounded or truncated (however I would be interested which one applies).
The “obvious” does not even compile:
BigInteger x = BigInteger.valueOf(73).pow(42);
BigInteger y = x.divide(Math.PI); // The method divide(BigInteger) in the type BigInteger is
// not applicable for the arguments (double)
System.out.println(y);
I expected this one to work:
BigInteger y = new BigDecimal(x).divide(BigDecimal.valueOf(Math.PI)).toBigInteger();
Unluckily, it gives an ArithmeticException: Non-terminating decimal expansion; no exact representable decimal result. This is true for π, of course…
Of course, this one works, but it is way too slow…
BigInteger y = BigInteger.valueOf(-1);
BigDecimal σ = BigDecimal.ZERO;
while(σ.compareTo(new BigDecimal(x)) < 0) {
y = y.add(BigInteger.ONE);
σ = σ.add(BigDecimal.valueOf(Math.PI));
}
What’s the correct, canonical way?
You have to add RoundingMode to divide function, otherwise java doesn't know how to round the division and gives you ArithmeticException
BigInteger y = new BigDecimal(y).divide(BigDecimal.valueOf(Math.PI), RoundingMode.HALF_UP).toBigInteger();
All Rounding types are well explained in the documentation link above.
This question already has answers here:
round up to 2 decimal places in java? [duplicate]
(12 answers)
Closed 5 years ago.
I'm doing a calculation on android studio (java) and the answer that I get back is like 4.654783632444251. I don't want the long answers. Preferably Two Decimal places would be ideal. Using Double.parseDouble
You can round it to two decimal places:
Math.round(myNumber * 100) / 100
Or you can format it using
String.format("%.2f", myNumber)
The second method even prints the decimal places if they are 0.
protected double round(double value, int places) {
if (places < 0) throw new IllegalArgumentException();
BigDecimal bd = new BigDecimal(value);
bd = bd.setScale(places, RoundingMode.HALF_UP);
return bd.doubleValue();
}
Just call this method entering your value and 2 places.