How can I convert from a Double object to an int? The following code works but seems slightly unconventional (with casting twice):
Double d = new Double(4.0);
int i = (int)(double)d;
When I try int i = (int)d, I get an error from Eclipse (Cannot cast from Double to int), which makes sense. Nevertheless, is there a simpler way of converting a Double object to an int?
Double.intValue()
is the provided method that does that conversion.
If you cast double to int you will loss decimal value.. so 4.99 double become 4 int. If still want to convert than try-
int i = d.intValue();
In your case you use
Double.intValue()
as a method to convert the Double Object to Integer.
Related
I have this:
String a = tonsescolhidos.getValue().toString();
int tons = Integer.parseInt(a);
float distlevel = 256/(tons - 1);
int temp;
temp = Math.floor(((float) (tons / distlevel) + 0.5)*distlevel);
tons = temp;
I get the error: "Incompatible types: possible lossy conversion from double to int" in the 5th line. How do i cast the variables in the right way.. what am I missing?
Math.floor only has one overload: double Math.floor(double). That always returns a double.
You would need to explicitly cast it to an int:
temp = (int) Math.floor(...);
But note that it is potentially lossy: double can store values too large to store in an int. So, you need to ensure that it's not a lossy operation by ensuring that the double's value is between Integer.MIN_VALUE and Integer.MAX_VALUE, by constraining the inputs appropriately.
Alternatively, rearrange your calculation so that you can do it all in integer math.
in Java I created an ArrayList of Double and I invoked the method list.add(1), however, I get an error. If I can assign an int to a double variable like this: double num = 1; due to automatic promotion, then why can't I add a 1 to ArrayList of Double via automatic promotion?
You're not trying to convert int to double; you're trying to convert int to Double, which is a combination of boxing and the implicit conversion from int to double. That doesn't work, even in a simple assignment:
// Error: incompatible types: int cannot be converted to Double
Double num = 1;
It doesn't even work for Long - you need to specify a long literal:
Long num1 = 1; // Invalid
Long num2 = 1L; // Valid
In your case, you just need to use a double literal, e.g.
list.add(1.0);
list.add(1D);
how to convert Float to Integer in java?
Float value = 30.0F
how to convert above value to Integer?
Please help me?
Use Float.intValue():
Integer i = value.intValue();
Note that this causes autoboxing, but since you're planning to create an Integer anyway, this won't have any performance impact.
Note also that you should pay attention to rounding: intValue() and an int cast round toward zero. For rounding to the nearest integer, use Math.round(), for rounding down use Math.floor(), for rounding up use Math.ceil(). If you need some other kind of rounding, you need to implement it yourself.
Try this:
Float f = new Float(10.5);
Integer i = new Integer((int)Math.ceil(f));
f.intValue() is the way to go..
new Float(value).intValue() or simly cast it to int int v = (int) value
You can just do this:
Float value = 30.0f;
Integer intVal = value.intValue(); // auto-boxing happens here
Use value.intValue() method.
Float value = 30.0F;
Integer intValue=Integer.valueOf(value.intValue());
What's wrong with this code
int numOfPrimes=pf.FindNumPrimes(10000);
Double frequency=((Double)numOfPrimes)/10000d;
Says
inconvertible types found : int
required: java.lang.Double Double
frequency=((Double)numOfPrimes)/10000d;
You're trying to autobox an int to a Double object, which is invalid.
Try:
int numOfPrimes=pf.FindNumPrimes(10000);
Double frequency=((double)numOfPrimes)/10000d;
Don't cast from primitives to wrapper types. Use lower-case double. And you don't need any casting in this case - the compiler does that automatically. The above can be simplified to:
int numOfPrimes = ...;
double frequency = numOfPrimes / 10000d;
You should almost never mix primitives with wrappers. And always prefer primitives (if possible). Use Double.valueOf(..) for conversion if you need to.
Double is not a primitive type (like int, long, byte, etc). It's a class type. You can convert between double and Double using autoboxing but not between int and Double.
You should either declare numOfPrimes as double or do the cast to a double instead of a Double
double numOfPrimes=pf.FindNumPrimes(10000);
Double frequency=((Double)numOfPrimes)/10000d;
or
int numOfPrimes=pf.FindNumPrimes(10000);
Double frequency=((double)numOfPrimes)/10000d;
or without unnecessary casts:
double numOfPrimes = pf.FindNumPrimes(10000);
Double frequency= numOfPrimes /10000d;
or
int numOfPrimes = 10;
Double frequency = numOfPrimes /10000d;
The Java code is as follows:
String s = "0.01";
int i = Integer.parseInt(s);
However this is throwing a NumberFormatException... What could be going wrong?
String s = "0.01";
double d = Double.parseDouble(s);
int i = (int) d;
The reason for the exception is that an integer does not hold rational numbers (= basically fractions). So, trying to parse 0.3 to a int is nonsense.
A double or a float datatype can hold rational numbers.
The way Java casts a double to an int is done by removing the part after the decimal separator by rounding towards zero.
int i = (int) 0.9999;
i will be zero.
0.01 is not an integer (whole number), so you of course can't parse it as one. Use Double.parseDouble or Float.parseFloat instead.
Use,
String s="0.01";
int i= new Double(s).intValue();
String s="0.01";
int i = Double.valueOf(s).intValue();
This kind of conversion is actually suprisingly unintuitive in Java
Take for example a following string : "100.00"
C : a simple standard library function at least since 1971 (Where did the name `atoi` come from?)
int i = atoi(decimalstring);
Java : mandatory passage by Double (or Float) parse, followed by a cast
int i = (int)Double.parseDouble(decimalstring);
Java sure has some oddities up it's sleeve
Using BigDecimal to get rounding:
String s1="0.01";
int i1 = new BigDecimal(s1).setScale(0, RoundingMode.HALF_UP).intValueExact();
String s2="0.5";
int i2 = new BigDecimal(s2).setScale(0, RoundingMode.HALF_UP).intValueExact();
suppose we take a integer in string.
String s="100";
int i=Integer.parseInt(s);
or
int i=Integer.valueOf(s);
but in your question the number you are trying to do the change is the whole number
String s="10.00";
double d=Double.parseDouble(s);
int i=(int)d;
This way you get the answer of the value which you are trying to get it.
use this one
int number = (int) Double.parseDouble(s);
Use Double.parseDouble(String a) what you are looking for is not an integer as it is not a whole number.
One more solution is possible.
int number = Integer.parseInt(new DecimalFormat("#").format(decimalNumber))
Example:
Integer.parseInt(new DecimalFormat("#").format(Double.parseDouble("010.021")))
Output
10