This question already has answers here:
How to round a number to n decimal places in Java
(39 answers)
Closed 7 years ago.
Is it possible to change a float value to a String? If possible, is it also possible to converting it to a String while rounding the number to the nearest integer?
For example if I have a float such as 2.335 then, can I change it to a String of value "2.335" or "2" (by rounding it)?
Use java Float class:
String s = Float.toString(25.0f);
if you want to round down a number, simply use the Math.floor() function.
float f = 2.9999f;
String s = Float.toString(Math.floor(f));//rounds the number to 2 and converts to String
first line rounds the number down to the nearest integer and the second line converts it to a string.
Another way of doing this is using the String.valueOf(floatNumber);
float amount=100.00f;
String strAmount=String.valueOf(amount);
To do this you can simply do
float example = 2.335
String s = String.valueOf(Math.round(example));
To convert a float to a String:
String s = Float.toString(2.335f);
Rounding can be done via
String.format("%.5g%n", 0.912385);
which returns 0.91239
For a more elaborate answer, see Round a number in Java
Your first requirement can be fullfilled with String.valueOf
float f = 1.6f;
String str = String.valueOf(f);
For roundoff you can use Math.round and not Math.floor. As Math.floor will convert 1.6 to 1.0 and not 2.0 while Math.round will roundoff your number to nearest integer.
Related
This question already has answers here:
Is floating point math broken?
(31 answers)
Closed 1 year ago.
I have a very weird result when I'm using my function and I think that I'm missing something with the rounding and double in java.
For example, when I provide the value 00159,300 for number and 100 for conversion I have 15930,000000000002 which is not possible!
public static String convertMultiply(String number, String conversion) {
number=number.replace(",", ".");
BigDecimal res=BigDecimal.valueOf(Double.valueOf(number)*Integer.valueOf(conversion));
res=res.stripTrailingZeros();
return res.toPlainString().replace(".", ",");
}
thanks in advance!
Double is an approximation of decimal values in Java. Instead, replace your line using double with:
BigDecimal res = (new BigDecimal(number)).multiply(new BigDecimal(conversion));
This question already has answers here:
java how to make user friendly percentage output from float number
(9 answers)
Closed 2 years ago.
I have a string value as below:
String percValue = "0.0209"
How can I convert this to something like as below
String formatedValue = "2.09%";
Can someone help me what is the simple and best way to convert this?
One good way would be to:
convert your percentage string to a number (needs to be a double type variable, so it can hold the decimal places...),
multiply the value by 100 to make it a percentage,
re-format the number in a string.
String percValue = "0.0209";
double percentage = Double.parseDouble(percValue) * 100;
String formattedValue = String.format("%.2f%%", percentage);
Explanation:
Double.parseDouble() takes your string as a parameter and returns a double value which you can do things like multiplication and addition with, and
String.format() lets you precisely control how your number is converted back to a String!
"%.2f" means "Take the next argument which is a floating-point variable and put it here, with two decimal places".
"%%" means "print a single '%'". You need two to "escape" it, since percent symbols are not literally interpreted in format strings.
You should parse the String into a double, multiply by 100, and then append the % sign to it as follows:
String percValue = "0.0209";
double per = Double.parseDouble(percValue);
String percentage = (per*100)+"%";
You need to parse your string value and then multiply by 100, something like this:
String percValue = "0.0209";
double value = ( Double.parseDouble(percValue)) * 100;
String formatedValue = value + "%";
Convert String to BigDecimal(for Big numbers) and multiply by 100.
String percValue = "0.0209";
BigDecimal temp=new BigDecimal(percValue).multiply(BigDecimal.valueOf(100)).stripTrailingZeros();
String formatedValue =temp.toString() + "%";
This question already has answers here:
Java keep trailing 0 in float operations
(3 answers)
Closed 4 years ago.
I have a requirement where I am getting a float value in java like the one below
1.1
1.10
10.10
when I convert this to string, I want it to be in the same way as
"1.1"
"1.10"
"10.10"
however, when I use the following method,
float fa = 25.50f;//Float.parseFloat("25.5");
String s = Float.toString(fa);
System.out.println(s); // i want the output to be 25.50, but it gives me 25.5
the result turns out to be the following
"1.1"
"1.1"
"10.1"
can somebody advise me how to get 1.10 as "1.10" with the zero in java
If you want it to store the whole number, why don't you just use a String?
I guess if you are getting "1.10" from somewhere, you are getting it as a String (or you would be getting just a "1.1").
There isn't (necessarily) a float value like 10.10f. There might be, but thing is: when you write down a float literal, you shouldn't expect that it really looks like the value you put down.
Only when representing numbers as strings you can uphold such requirements regarding formatting.
In other words, you probably should read this for example.
How it is printed is determined by how you format a number, the float is just a value, and it's actual representation is binary, not decimal.
String s = String.format("%.2f", 25.5f); // 25.50
I highly recommend using double which is simpler to use, and half a trillion times more accurate.
If your float value comes from String I suggest below solution:
public static void main(String[] args) {
String floatValue = "25.20";
String[] splittedFloat = floatValue.split("[.]");
int numberOfDecimalPlaces = splittedFloat[1].length();
float value = Float.valueOf(floatValue);
System.out.printf("%." + numberOfDecimalPlaces + "f\n", value);
}
First you declare your value as String. Then split it with "dot" and check the length of decimal places. Then you parse it into your float value and you do whatever you want with this value. And finally you cat print it with format like previous because you have number of decimal places of this float value.
The output of this code is:
25.20
There is no way to hold 25.20 value in float because the actual value is 25.2 and that 0 is formatting.
I know there is a way of forcing a float to have 3 decimal points, but how do I make a string representation "4.00000009" retain 3 decimal points after I turn it into a float? Float.parseFloat() rounds it to 4.0. Not using extra libraries would be ideal.
If you're guaranteed that the String is properly formatted, you can take a substring based on the index of the decimal.
Alternatively, you can parse it, multiply by a thousand, round it, and divide it by a thousand.
However, this is going to be bad for you in the long run. Floating point numbers don't fare so well when exact values are needed. Consider BigDecimal instead.
This utility method takes a String and turns it into a float with 3 decimals places:
public static float getFloat(String s) {
BigDecimal decimal = new BigDecimal(s);
decimal = decimal.setScale(3, RoundingMode.HALF_UP);
return decimal.floatValue();
}
This question already has answers here:
Convert Double to Binary representation?
(7 answers)
Closed 7 years ago.
I want to create a binary represenation of a floating-point number and be able to parse that number back when needed. By "binary representation" I do not mean "0.00101" but something like "101000101", that is to say, a sequesnce of 0's and 1's with no decimal separator. I need a way to both create such representation in String for a double and to parse a double of a String.
Please do not mention the X Y problem because I do definitly need this method (something like "unsigned binary value").
Thank you in advance.
Convert Double to Binary representation? seemed to solve the problem with parsing double to String but I still need help with doing the opposite: from binary to double.
To convert the bits of a double to a String, you can use Double.doubleToLongBits, which creates a long with the same bits as the double, followed by Long.toBinaryString to convert it to a String with the bits as characters.
double test = 0.5;
long doubleBits = Double.doubleToLongBits(test);
String doubleBitsStr = Long.toBinaryString(doubleBits);
System.out.println(doubleBitsStr);
Output: 11111111100000000000000000000000000000000000000000000000000000
To convert back, use Long.parseLong with a radix of 2 and Double.longBitsToDouble.
doubleBits = Long.parseLong(doubleBitsStr, 2);
test = Double.longBitsToDouble(doubleBits);
System.out.println(test);
Output: 0.5
To convert the bits of a float to a String, you can use Float.floatTointBits, which creates an int with the same bits as the float, followed by Integer.toBinaryString to convert it to a String with the bits as characters.
float test2 = 0.5f;
int intBits = Float.floatToIntBits(test2);
String intBitsStr = Integer.toBinaryString(intBits);
System.out.println(intBitsStr);
Output: 111111000000000000000000000000
To convert back, use Integer.parseInt with a radix of 2 and Float.intBitsToFloat.
intBits = Integer.parseInt(intBitsStr, 2);
test2 = Float.intBitsToFloat(intBits);
System.out.println(test2);
Output: 0.5
Would Integer.toBinaryString(Float.floatToIntBits(yourNumber)); not work?