Java: Convert scientific notation to regular int

Question

How do I convert scientific notation to regular int For example: 1.23E2 I would like to convert it to 123

Thanks.

Hear

Do you have the string "1.23E2" or a float that is equal to 1.23e2? – Fovea

Answer 1

If you have your value as a String, you could use

int val = new BigDecimal(stringValue).intValue();

Unbecoming

I used something like: String val = new BigDecimal(stringValue).toPlainString(); since I wanted the value back as String. Thanks for pointing me to BigDecimal – Hear

Fighting with some scientific-notation-formatted value from Excel (using POI) which happens to be a date in format "yyyyMMdd". This was really helpful! – Toots

Old post but it's worth noting that the method new BigDecimal(stringValue).intValueExact() will only return int value if it fits in the range and has no fractional part. Otherwise it will throw ArithmeticException. Might avoid unexpected truncation/rounding. – Talley

Not working for high range like, 5000000000 – Echinoderm

Answer 2

You can just cast it to int as:

double d = 1.23E2; // or float d = 1.23E2f;
int i = (int)d; // i is now 123

Megargee

I actually tried this before posting the question here on stackoverflow but for some reason I decided not to use it since I was afraid of losing information during this conversion to Double and then to Int. But I guess it is a valid way. – Hear

This is not valid. You are correct in thinking that some information will be lost. This is because doubles are 8 bytes while ints are 4 bytes. Take this as an example and notice the large difference after casting. double dlow = Double.parseDouble("-2299999999"); int ilow = (int) dlow; System.out.println("dlow="+String.valueOf(dlow)); System.out.println("(int)dlow="+String.valueOf(ilow)); System.out.println("ilow-dlow="+String.valueOf(ilow-dlow)); dlow=-2.299999999E9 (int)dlow=-2147483648 ilow-dlow=1.52516351E8 – Murmurous

Answer 3

I am assuming you have it as a string.

Take a look at the DecimalFormat class. Most people use it for formatting numbers as strings, but it actually has a parse method to go the other way around! You initialize it with your pattern (see the tutorial), and then invoke parse() on the input string.

Melt

Answer 4

Check out DecimalFormat.parse().

Sample code:

DecimalFormat df = new DecimalFormat();
Number num = df.parse("1.23E2", new ParsePosition(0));
int ans = num.intValue();
System.out.println(ans); // This prints 123

Hygroscopic

Answer 5

You can also use something like this.

(int) Double.parseDouble("1.23E2")

Knell

Answer 6

You can implement your own solution:

String string = notation.replace(".", "").split("E")[0]

Charlettecharley

If the string looks like "1.23E4" you'll get 123 instead of 12300; or "1.234E1" will result in 1234 instead of 12. The string needs to be parsed properly using existing facilities mentioned in other answers for the past 10 years.. – Krystinakrystle