Int to Double?

I look in APIs, there is doubleValue() method, but when I use it for transfer int to double, such as: IntVariable.doubleValue()
the complier report:
int cannot be dereferenced
What is the problem? How can I transfer int to double.

1 error
How can I transfer int to Integer?What error? My example compiles. It also shows how to transfer an int to an Integer. The 0 you see is an integer. You can replace that with an integer variable. You have to use the operator new to create an Integer with a certain value which, to my knowledge, can't be changed after that.

Similar Messages

Int and Double help

I have a new lab and have most everything down right except that I am trying to create an int array that has double methods within it here is what I have so far:
       public static void main(String[] args) {
               Scanner in = new Scanner(System.in);
               System.out.print("How many numbers? ");
               int numNum = in.nextInt();
               System.out.print("How many intervals? ");
               int intervals = in.nextInt();
               System.out.print("\nHistogram");
               System.out.print("\n--------------------------------------------------------");
               double[] n = Generator.getData(numNum);
               double min = getMin(n);
               double max = getMax(n);
               double range = max-min;
               double width = (range/intervals);
               int[] histogram = new int [intervals];
               for(int index = 1; index <= intervals; index++){
                       if(index <= intervals){
                               histogram[index] = ();
               for     (int i = 1; i <= intervals; i++){
                       System.out.print("\n   " + i);
                       System.out.print(" " + range);
               System.out.print("\n--------------------------------------------------------");
       private static double getMin(double[]n){
               double lowest = n[0];
               for (int index =1; index < n.length; index++){
                       if (n[index] < lowest){
                               lowest = n[index];
               return lowest;
       private static double getMax(double[]n){
               double highest = n[0];
               for (int index =1; index < n.length; index++){
                       if (n[index] > highest){
                               highest = n[index];
               return highest;
       private static int getArray(double[]n,double intervals, double width){
               int[] array = new int [intervals];
               for(int index=0; index <= intervals; index++ ){
                       if(index <= intervals){
                               array[index] = (n[index]/width);
               return array;
       }I am stuck of the getArray class. Any help is greatly appreciated.

haphilli wrote:
I appreciate the help I am still just not getting it it is supposed to return this:
How many numbers? 100
How many intervals? 10
Histogram
1 ****(4)
2 ******(6)
3 ***********(11)
4 *****************(17)
5 **************************(26)
6 *************************(25)
7 *******(7)
8 ***(3)
9 (0)
10 *(1)
The program performs the following actions:
1. Ask the user to enter the number of numbers that will be generated and the number of intervals that will be used in the histogram, and input the two values;
2. Generate the required number of pseudo-random numbers by using the double[] Generator.getData(int n), which, given the number of numbers to generate, n, returns an array of double of size n containing the generated numbers;
3. Compute the range of data values (by finding the maximum and the minimum and taking their difference); then compute the width of each equally-sized interval (by dividing the whole range by the number of intervals specified by the user); finally, compute the number of data numbers falling in each interval and store these frequencies in an array of integers;
4. Output the histogram of the data as displayed in the sample run above: each bar starts with an index (1 through the number of intervals), followed by a number of '*' equal to the number of numbers in that range, followed by the number of '*' in parentheses.
Note: Pay attention to detail. Make your output look like the output in the sample run. However, note that your program must be able to produce the correct histogram for arbitrary data, not just for the specific data generated by Generator.getData().Yes, but we're thus far not addressing the proper operation of your code - we're still in the debugging phase.
After the code compiles cleanly, and you get all the obvious "mechanical" things fixed, then we can start addressing the design.
Why do I say that? Ordinarily the design comes first. But there are some syntax issues that really need to be addressed before you can appreciate what is wrong with the logic flow. You can work out the design in your head, but let's fix syntax errors before we code it up, so that we all have a good understanding of the the mechanicals.

How to change the waveform-type inside of the waveform graph from int to double?

Hello,
attached you find a vi with two waveform-graphs.
When i rightclick them and select "create constant" then it creates the constant.
The difference between the two graphs is, that one creates a double-array inside the constant and the other graph creates an int-array inside
The question is: Where can i change inside of the int-graph that it also creates a double-array in the constant?
(Problem is that all double-waveforms send into this graph are changed to int and rounded in the display)
Thanks for the help
Attachments:
waveform.vi ‏27 KB

The datatype of a chart or graph is determined by the last thing you wired to it. By default, they are simple doubles or arrays of doubles. My guess is that you first wired a waveform with an integer data type to the graph. It should switch automatically to a double waveform graph if you wire a waveform which contains double data to it. If it does not, that is probably a bug. If you have a VI in this state, please post it and I will report it to R&D.
Thanks!
This account is no longer active. Contact ShadesOfGray for current posts and information.

Why use int over double?

i am using the book beginning java 2. and there is a example showing how the math class works
the program calculates the radius of a circle in feet and inches given that the area is 100 square feet:
public class MathCalc
public static void main(String[]args)
double radius = 0.0;
double circlearea= 0.0;
int feet = 0;
int inches = 0;
radius = Math.sqrt(circleArea/Math.PI);
feet = (int)Math.floor(radius);
inches = (int)Math.round (12.0 * (radius-feet));
System.out.println( Feet + "feet" + inches + "inches");
the output will be 5 feet 8 inches.
my question is why bother with using 'int', why not simply use 'double' for all your variables?
in feet and inches 'int' has been used as the result would have been a floating value. so casting as been used. But doesnt that complicate things?cant one just use long for all variables and forgot about worrying whether the value will fit or not.
thanks
Ali

i am using the book beginning java 2. and there is a
example showing how the math class works
the program calculates the radius of a circle in feet
and inches given that the area is 100 square feet:
public class MathCalc
public static void main(String[]args)
double radius = 0.0;
double circlearea= 0.0;
int feet = 0;
int inches = 0;
radius = Math.sqrt(circleArea/Math.PI);
feet = (int)Math.floor(radius);
inches = (int)Math.round (12.0 *
d (12.0 * (radius-feet));
System.out.println( Feet + "feet" + inches +
"inches");
the output will be 5 feet 8 inches.
my question is why bother with using 'int', why not
simply use 'double' for all your variables?There are several reasons to use int (when appropriate) rather than double. More generally, there are several reasons to use integer arithmetic instead of floating point.
First, integer arithmetic is precise whereas floating point arithmetic is always subject to imprecision. E.g. 6 / 2 always equals 3, 6.0 / 2.0 may equal something like 3.000000000000001.
Second, (related to the above) the results of integer arithmetic operations will not vary from one machine to the next. The results of the same floating point operation may vary from one machine to the next.
Third, integer arithmetic is always faster than floating point.
>
in feet and inches 'int' has been used as the result
would have been a floating value. so casting as been
used. But doesnt that complicate things?The results are cast back to an int because it would look silly and meaningless to print a result of, for instance, 5.00000001 feet, 8.00045 inches.
cant one just
use long for all variables and forgot about worrying
whether the value will fit or not. No. You should never disregard whether the results of arithmetic operations will overflow the size of the word you are using. Even though a long type can contain a pretty huge number, you can still easily overflow it and get nonsensical results.
Also, a 32 bit word is the native size for most of the machines most of us use. This means that arithmetic operations are fastest on int types (for most of us). This shouldn't be a primary design consideration but it should be taken into account.

Dimensions - int and double mixed?

Dimension x = new Dimension(int_1, int_2);
int height = x.height;
int width = x.width;
double height_d = x.getHeight();
double width_d = x.getWidth();When you create a dimension you give it to integers as the width and height. However, if you call getHeight() or getWidth() it returns double-precision values. What's the point? Why does it use int/doubles?
Thanks

The methods getWidth/getHeight are inherited from RectangularShape.
We have:
Rectangle2D extends RectangularShape
Rectagle extends Rectangle2D //implemeted with ints
Rectangle2D .Float extends Rectangle2D //implemeted with floats
Rectangle2D .Double extends Rectangle2D //implemeted with double
So the implementations are providing the precision. Since the getWidth/getHeight methods are common
to the hierarchy they return doubles to avoid loss of precision in the Rectangle2D .Double case.
On the other hand, if I'm working with a java.awt.Rectangle I just access the public width and height fields
directly.

Asking for directions - Transforming int // short // double into string

I've been searching around the forums for a tutorial to transform an int or short or long back into a string, and I can't seem to find one. Could a kind person direct me to the tutorial for making integers into strings?

String.valueOf(...)

Is there any way to randomize ints or doubles?

I'm not sure if this is possible but let's say I decide to choose 5 numbers. (e.g. 1, 2, 3, 4, 5) Is there any way to change these numbers and make them random numbers? I know this might sound strange but I'm thinking about making a program: A online lottery service, where the numbers are randomized every time a lottery is held. I hope some one here gets what I'm saying. If there's a way, can someone tell me thx!

import java.util.Random;
Random r = new Random();
int i = r.getInt(--size--);
http://java.sun.com/j2se/1.4.2/docs/api/java/util/Random.html

Overloading ambiguity between "std::pow(double, int)" and "std::pow(long do

hello all,
we have a problem with sources coming from visual c++, i can reproduce the problem with the small code:
$ cat test.cc
#include <math.h>
int main()
double kk;
int j11;
j11=4;
kk=pow(2,j11);
$ CC test.cc
"test.cc", line 8: Error: Overloading ambiguity between "std::pow(double, int)" and "std::pow(long double, int)".
1 Error(s) detected.we are on linux, with sun studio 12u1
thanks in advance for help,
gerard

The issue is whether the standard headers associated with the compiler have the overloads required by the standard. If the required overloads are present, the original call of std::pow is ambiguous, and the compiler will report it.
If you have a recent version of Visual C++, I'd be very surprised if the function overloads were not available. Possibly you are using a compiler option, perhaps a default option, that hides the overloaded declarations. In that case, some C++ code that conforms to the standard would not behave correctly when used with the compiler in that mode.
The correct approach is to use the compiler in standard-conforming mode so that code you write will be accepted by other standard-conforming compilers. That is, after all, the purpose of the standard.

Question with how to know if a String contains int,double,or common String?

I'm doing table sorting now and wanna make a "generic" method of comparing 2 Strings:
if they are common Strings , just use String.compareTo()
if they are int or double etc, compare which is bigger
BTW: I have thought about using try{...}catch{...} to catch NumberFormatException , but i don't wanna use this way.

check to see if each char is numeric? (or '.')....
I dont see much wrong with parseInt/parseDouble +
exception catching thothe compare() method is invoked hundreds and thousands times, so I guess using too much try{}catch{} is not a good thing, am I right?

Double to Int Help Please

Ok, so, now, I am about to take my final in Java on Thursday, and I thought I would try a little prog on my own. But, I am having trouble with the most basic stuff!
Here is prog: http://www.willdesign4you.com/BindingCalc.java
I have two issues:
1. In this segment:
if((numStrips % 10) > 0)
output.append("\n(Number of Strips needed has been rounded up " +
" to nearest 1.)");
numStrips += 1;
the method works fine unless the result is like 10.05 or in that range, then it isn't performing the function.
2. In the rest of the methods, I need to be able to do math functions in decimals to get the needed accuracy. But, I cannot use * with a double, and I can't use int for double or float numbers. What am I doing wrong?
What I need to do at the end to calculate yardage is say something like this:
Yardage = numStrips * StripWidth
Round up Yardage to the nearest 1/4" yard.
Can anyone help me please?
Thanks,
Kimberly

Sorry! Forgot!
Maybe you should have a look at the BigDecimal and BigInteger classes. Using them you can perform a number of operations. The example I gave before do not perform any roundings. So, if d = 123.56 i will still be 123.
Klint

Changing an Array of Strings to an Array of Double or Int

How would I change a string of arrays to ints or doubles...here my code:
     File inputFile = new File("testing");
        FileReader in = new FileReader(inputFile);
     BufferedReader bufin = new BufferedReader(in);
     String c;
     String[] x = new String[300];
     String[] Xcoord = new String[300];
     String[] Ycoord = new String[300];
     int counter = 1;
            while ((c = bufin.readLine()) != null)
          if( counter >= 3 )
               x[counter] = c;
               String[] xySplit = x[counter].split(" ");
               System.out.println("X: "+xySplit[0]+" Y: "+xySplit[2]);
               Xcoord[counter] = xySplit[0];
               Ycoord[counter] = xySplit[2];
           in.close();

Use a parsing method:int i = Integer.parseInt (s);
double d = Double.parseDouble (s);>> String[] x = new String[300];
You seem like you want to use a list instead.

How do you invoke a method with native int array argument?

Hi,
Will someone help me to show me a few codes samples on how to invoke a method which has only one argument, an int [] array.
For exampe:
public void Method1(int [] intArray) {...};
Here is some simple code fragment I used:
Class<?> aClass = Class.forName("Test2");
Class[] argTypes = new Class[] {int[].class};
Method method = aClass.getDeclaredMethod("Method_1", argTypes);
int [] intArray = new int[] {111, 222, 333};
Object [] args = new Object[1];
args[0] = Array.newInstance(int.class, intArray);
method.invoke(aClass, args);I can compile without any error, but when runs, it died in the "invoke" statement with:
Exception in thread "main" java.lang.IllegalArgumentException: object is not an instance of declaring class
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
     at java.lang.reflect.Method.invoke(Unknown Source)
     at Test1.invoke_Method_1(Test1.java:262)
     at Test1.start(Test1.java:33)
     at Test1.main(Test1.java:12)
Any help is greatly appreciated!
Jeff

Sorry, my bad. I was able to invoke static methods and instance methods with all data types except native int, short, double and float, not sure the proper ways to declare them.
After many frustrating hours, I posted the message for help, but at that time, my mind was so numb that I created a faulted example because I cut and pasted the static method invocation example to test the instance method passing int array argument.
As your post suggested, "args[0] = intArray;", that works. Thanks!
You know, I did tried passing the argument like that first, but because I was not declaring the type properly, I ended up messing up the actual passing as well as the instantiation step.
I will honestly slap my hand three times.
jml

Formatting a Double to a String for Swing output

Hi, I'm new to Java and I'm working on a project with AWT & Swing. I'm trying to read in a user entered number, convert it to a double, work on it and then output the String value of the result with only two decimal places. The code I have is:
public void actionPerformed(ActionEvent e)
double result = 99;
double temp;
DecimalFormat newTemp = new DecimalFormat("#,###.00");
if (e.getSource() == bConvert1)
temp = (Double.parseDouble(tTemp1.getText().trim()));
result = (temp*1.8)+32;
newTemp.format(result);
tResult1.setText(String.valueOf(result));
else if (e.getSource() == bConvert2)
temp = (Double.parseDouble(tTemp2.getText().trim()));
result = (5.0/9)*(temp-32);
newTemp.format(result);
tResult2.setText(String.valueOf(result));
This is working for some values, but for some values entered, the result displayed is just the remainder.

The reason it doesn't always work could be because DecimalFormat (for reasons known only to Sun) uses ROUND_HALF_EVEN...
This means that you will have to round the value to the number of decimal places you require before calling format()
I use something like the following formatter class
class Formatter {
public static final int DEFAULT_PRECISION = 2;
public static final String DEFAULT_PATTERN = "#.00";
public static final String ZEROS = "0000000000000000";
public static String convertDoubleToString(Double d) {
    return convertDoubleToString(round(d, DEFAULT_PRECISION), DEFAULT_PATTERN);
public static String convertDoubleToString(double d) {
    return convertDoubleToString(round(d, DEFAULT_PRECISION), DEFAULT_PATTERN);
public static String convertDoubleToString(Double d, int precision) {
    return convertDoubleToString(round(d, precision), "#." + ZEROS.substring(precision));
public static String convertDoubleToString(double d, int precision) {
    return convertDoubleToString(round(d, precision), "#." + ZEROS.substring(precision));
public static String convertDoubleToString(Double d, String pattern) {
    return new DecimalFormat(pattern).format(d.doubleValue());
public static String convertDoubleToString(double d, String pattern) {
    return new DecimalFormat(pattern).format(d);
private static final double round(Double d, int precision) {
    double factor = Math.pow(10, precision);
    return Math.round((d.doubleValue() * factor)) / factor;
private static final double round(double d, int precision) {
    double factor = Math.pow(10, precision);
    return Math.round((d * factor)) / factor;
}

Rounding Doubles to Two Decimal Places

Hi All,
I've searched the archive and found a few different posts regarding restricting the number of decimal places in doubles. However they all suggest different methods, BigDecimal, NumberFormat etc.
Which is the simplest method of rounding a number say 10.023445656 to 10.02?
I tried using the java.text.NumberFormat but this turns the double into a string and I need the end result to be a double.
Thanks

Hi All,
I've searched the archive and found a few different
posts regarding restricting the number of decimal
places in doubles. However they all suggest different
methods, BigDecimal, NumberFormat etc.
Which is the simplest method of rounding a number say
10.023445656 to 10.02?
I tried using the java.text.NumberFormat but this
turns the double into a string and I need the end
result to be a double.
ThanksI ahve a small code that can do the work for u:
import java.text.*;
double format(double val, int dec){
    double multiple=Math.pow(10,dec);
    val=Math.round(val*multiple)/multiple;
    DecimalFormat df=new DecimalFormat("0.00");
    String format=df.format(val);
   double dval=Double.parseDouble(format);
   return dval;
}//end of functionHope that helps!

Round up double to 2 decimals

How to round up double to 2 decimals? where in API i should look up? Thank you for your help!
e.g., Book (including tax) :14.99 + 14.99 * 10% = 16.489 ---> 16.49

     * Scale decimal number via the rounding mode BigDecimal.ROUND_HALF_UP.
     * @param value Decimal value.
     * @param scale New scale.
     * @return Scaled number.
     * @since 1.8.3
    static public double getScaled(double value, int scale) {
        double result = value; //default: unscaled
        //use BigDecimal String constructor as this is the only exact way for double values
        result = new BigDecimal(""+value).setScale(scale, BigDecimal.ROUND_HALF_UP).doubleValue();
        return result;
    }//getScaled()

Int to Double?

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