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Trouble with area
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I have been trying to build a Java program to prompt the user to enter the radius of a circle and the diameter, circumference, and area will be output through a "System.out.printf" statement. I can get the program to prompt for the radius and it will display the diameter, but will not identify the Area or Circumference. I keep getting an error with the Math variable. What could be wrong with this code for Area:
System.out.printf("Area is %d\n", (x * x * math.PI) );
System.out.printf("Area is %d\n", (x * x * math.PI) );
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Join Date: Jun 2009
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Practically a Posting Shark
Ahem!
Given only radius gives you all the other data. No need to input.
Circumference = 2 * PI * r
Area = PI * r * r
etc.
I'm also assuming your x is entered as a Floating-Point value.
Given only radius gives you all the other data. No need to input.
Circumference = 2 * PI * r
Area = PI * r * r
etc.
I'm also assuming your x is entered as a Floating-Point value.
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Last edited by wildgoose; Jul 2nd, 2009 at 6:44 pm. Reason: error
Thanks, that really cleared up my format for the Area and Circumference, but I am still getting an error for diameter. Honestly, I do not know why. I have eliminated one problem by capitalizing the "M" in Math.PI, but can't get over the diameter issue.
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Practically a Posting Shark
Please post your code!
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And also post what error you are getting. If you are successfully reading in the radius, then 2 * radius should give you the diameter without problems as long as the radius is declared as the correct type (i.e. float or double).
Last edited by BestJewSinceJC; Jul 6th, 2009 at 9:45 pm.
Out.
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Originally Posted by BestJewSinceJC 
And also post what error you are getting. If you are successfully reading in the radius, then 2 * radius should give you the diameter without problems as long as the radius is declared as the correct type (i.e. float or double).
"Diameter is Exception in thread "main" java.util.IllegalFormatConversionException: f != java.lang.Integer"
System.out.print( "declare radius of circle: " ); // prompt for input
x = input.nextInt(); // read first integer
//display results
System.out.printf("Area is %f\n", (x * x * Math.PI) );// output the Area
System.out.printf("Circumference is %f\n", (2 * x * Math.PI) );// output the circumference
System.out.printf("Diameter is %f\n", (2 * x) );// output the diameter using printf
}//end main
}//end class Circle
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Join Date: Jun 2009
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Practically a Posting Shark
Post your entire code! Errors can be misleading without seeing everything in context!
For example if x is an integer or a double it can cause a problem with that printf. The fact that it was multiplied with a float (PI) would make the result a float.
For example if x is an integer or a double it can cause a problem with that printf. The fact that it was multiplied with a float (PI) would make the result a float.
Last edited by wildgoose; Jul 7th, 2009 at 1:58 am. Reason: addendum
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Posting Shark
Because x is assigned from an input.nextInt(), I assume it's declared as int, so:
%f requires a floating point value, but 2*x is an integer value. Change the format to %d when you print the diameter, OR change the calculation to 2.0*x so the result is floating point.
%f requires a floating point value, but 2*x is an integer value. Change the format to %d when you print the diameter, OR change the calculation to 2.0*x so the result is floating point.
Last edited by JamesCherrill; Jul 7th, 2009 at 1:28 pm.
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Originally Posted by JamesCherrill
Because x is assigned from an input.nextInt(), I assume it's declared as int, so:
%f requires a floating point value, but 2*x is an integer value. Change the format to %d when you print the diameter, OR change the calculation to 2.0*x so the result is floating point.
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